Applied Epidemiology

MPH Ist Year

APPLIED EPIDEMIOLOGY

Prabesh Ghimire


MPH 19th Batch

Table of Contents UNIT 1: COMMUNICABLE AND NON-COMMUNICABLE DISEASES ................................................................................ 4 Concept and Approaches of Communicable and Non-Communicable Diseases ...................................................... 4 Epidemic ............................................................................................................................................................... 6 Epidemiologic Transmission of Infectious and Non Infectious Diseases ................................................................... 6 Emerging, Remerging Diseases and Existing Diseases .............................................................................................. 9 Epidemiological Overview of Major Communicable Disease as Public Health Problem in Nepal...........................11 Cholera ................................................................................................................................................................ 11 Srub Typhus ........................................................................................................................................................ 12 Ebola Virus .......................................................................................................................................................... 13 Zika Virus............................................................................................................................................................. 15 Dengue ................................................................................................................................................................ 16 Malaria ................................................................................................................................................................ 17 Kala-azar (Visceral Leishmaniasis)....................................................................................................................... 19 Lymphatic Filariasis ............................................................................................................................................. 20 Influenza ............................................................................................................................................................. 21 Tuberculosis ........................................................................................................................................................ 23 Leprosy ................................................................................................................................................................ 25 HIV & AIDS .......................................................................................................................................................... 26 Measles (Rubeola) .............................................................................................................................................. 28 Rubella(German Measles)................................................................................................................................... 29 Typhoid Fever ..................................................................................................................................................... 29 Epidemiological Overview of Major Non-Communicable Disease as Public Health Problem in Nepal...................30 Atherosclerosis ................................................................................................................................................... 30 Road Traffic Accidents ........................................................................................................................................ 31 Diabetes .............................................................................................................................................................. 32 Prevention, Control and Management of Communicable and Non-communicable Diseases ................................ 33 SOCIAL EPIDEMIOLOGY ............................................................................................................................................... 34 Concept, Scope and Process.................................................................................................................................... 34 Social Determinants of Health ................................................................................................................................ 36 Evidence Based Public Health Practice.................................................................................................................... 38 Distinction between Evidence Based Public Health (EBPH) and Evidence Based Medicine (EBM).........................39 Critical Appraisal of Research Article ...................................................................................................................... 39

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UNIT 1: COMMUNICABLE AND NON-COMMUNICABLE DISEASES Concept and Approaches of Communicable and Non-Communicable Diseases Natural History of Disease Natural history of disease refers to the progress of a disease process in an individual over time, without treatment or intervention. The process begins with exposure to or accumulation of factors capable of causing diseases. Without medical intervention, the process ends with recovery, disability or death. Phases in the natural history of disease i. Pre-pathogenesis phase - The mere presence of agent host and environment is not enough to cause the disease. As long as these epidemiological triad is in an equilibrium, disease will not be initiated. - The process of human disease would be initiated only if there is an appropriate interaction and a loss of equilibrium. For example if we drink contaminated water, we would become susceptible to typhoid fever. - The point which needs to be noted is that in any disease, there is a phase between the state of perfect health and the point from where actual a pathological process of the disease starts. This phase is call as the phase of pre-pathogenesis. - This stage occurs even before the human being is actually involved with the disease process. Thus people in the stage of susceptibility or pre-pathogenesis stage are not in a state of health, though they may not be having any disease. ii.

Pathogenesis Phase

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The pathogenesis phase begins with the entry of the disease agent in the susceptible human host The disease agent multiplies and induces tissue and physiologic changes, progresses through a period of incubation and later through early and late pathogenesis. The final outcome of the disease may be recovery, disability or death. The infection may be clinical or sub-clinical,

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typical or atypical or the host may become a carrier with or without having clinical disease as in the case of poliomyelitis. In chronic diseases, the early pathogenesis phase is less dramatic. In this case it is referred to as pre-symptomatic phase. During this stage there is no manifestation of disease. The pathological changes are essentially below the level of clinical horizon. In many chronic diseases, the disease agent-host-environment interaction is not well understood.

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Chain of (Infection) Disease Transmission The chain of infection is a model used to explain the components necessary for disease transmission. By using a chain analogy, we can better understand that all components must be in place for a disease transmission to take place. The chain of infection includes the following components i. -

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Causative agent: The causative agent/pathogen can include bacteria, viruses, worms, chemicals or any other plant or animal substances or factor that can causes disease, disability, illness, syndrome, or death. The greater the organism's pathogenecity, virulence and invasiveness, the greater the possibility that the organism will cause an infection. Source or Reservoir: Source of infection is defined as the person, animal, object or substance from which an infectious agent passes or is disseminated to the host. Reservoir is defined as any person, animal, arthropod, plant, soil or substance in which an infectious agent lives and multiplies and on which it depends primarily for survival, and where it reproduces itself in such a manner that it can be transmitted to a susceptible host. In hookworm infection, the reservoir is man but the source of infection is contaminated soil. In tetanus, both the reservoir and source of infection is soil.

iii. Mode of Transmission - Once a pathogen or agent leaves its reservoir, it goes by mode of transmission to a susceptible host. - The mode of transmission may be either direct transmission (direct contact, droplet infection, contact with soil,etc.) or by indirect (droplet nuclei, fomite, vehicle borne substances,etc.) iv. Susceptible Host - The final link in the chain of transmission is susceptible individual or host. - The host is generally protected from invasion of pathogens by the skin, mucous membranes and physiological responses and the body's immune system. - So the infectious agent must find a portal of entry by which it may enter the host. There are many portal of entry (respiratory tract, alimentary tract, genitourinary tract, skin, etc.) - If a pathogen is able to enter the host, the result will most likely be illness if the has no immunity to the pathogen. Susceptibility is based on the levels of susceptibility.

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Epidemic The unusual occurrence in a community or region of disease, specific health behaviour or other health related events clearly in excess of expected occurrence is called epidemic. Two major types of epidemics may be distinguished i. Common-source epidemics a. Point source epidemic b. Continuous exposure epidemic ii. Propagated epidemic a. Person to person epidemic b. Arthropod vector c. Animal reservoir i. Common Source Epidemic a. Point source epidemic - The main features of a point source epidemic are: • The epidemic curve rises and falls rapidly, with no secondary waves • The epidemic tends to be explosive, there is clustering of cases within a narrow interval of time • All the cases develop within one incubation period of disease b. Multiple source epidemic - Sometimes the exposure from the same source may be prolonged- continuous, repeated or intermittent, not necessarily at the same time or place. - E.g. a prostitute may be a common source in a gonorrhoea outbreak. ii. -

Propagated epidemic A propagated epidemic is most often of infectious origin and results from person to person transmission of an infectious agent (e.g. epidemic of hepatitis) The epidemic usually shows a gradual rise and tails off over a much longer period of time.

Epidemiologic Transmission of Infectious and Non Infectious Diseases Epidemiologic Transition The epidemiologic transition describes changing patterns of population distributions in relation to changing patterns of mortality, fertility, life expectancy, and leading causes of death. There are two main components of the transition: i. Changes in population growth trajectories and composition, especially in the age distribution from younger to older. ii. Changes in patterns of mortality, including increasing life expectancy and reordering of the relative importance of different causes of death. Epidemiologic Transition Theory The epidemiologic transition theory was formulated by A.R. Omran in 1971. In his 1971 article, he wrote, “Conceptually, the theory of epidemiologic transition focuses on the complex change in patterns of health and disease and on the interactions between these patterns and their demographic, economic and sociologic determinants and consequences”

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Omran’s formulation of the theory consisted of five propositions i. Proposition One: The theory of epidemiologic transition begins with the major premise that mortality is a fundamental factor in population dynamics. ii. Proposition Two: During the transition, a long term shift occurs in mortality and disease patterns whereby pandemics of infection are gradually displaced by degenerative and man-made diseases as the chief form of morbidity and primary cause of death. Typically, mortality patterns distinguish three major successive stages of the epidemiologic transition a. Stage One: The age of pestilence and famine - This stage is characterized by high and fluctuating mortality rates, thus precluding sustained population growth. - In this stage, the average life expectancy at birth is low and variable, vacillating between 20 and 40 years b. Stage Two: The age of receding pandemics - This stage is marked by progressive decline in mortality rates that becomes steeper as epidemics become less frequently or disappear. - The average life expectancy at birth increases steadily from 30 to about 50 years. - Population growth is sustained and begins to describe an exponential curve. - The major driving forces in this stage of transition are sanitation improvements, control of major outbreaks of infectious diseases, and medical breakthroughs. c. -

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Stage Three: The age of degenerative and man-made diseases In this phase, it is theorized that infectious disease pandemics are replaced as major causes of death by degenerative diseases, and infectious agents as the major contributor to mortality and morbidity are overtaken by anthropogenic causes. With decline in mortality rates, average life expectancy increases to more than 50 years, fertility becomes more important to population growth, and the anthropogenic and biologic determinants of disease also change. This transition is typically associated with the late 19th and 20th centuries in developed countries. In 1983, Omran recognized the need to update his theory to incorporate a more extended description of the transition, as emerging analyses of transition patterns based on historical data did not fit the original model. He added two stages to his original theory:

d. Stage Four: The age of declining cerebrovascular mortality, ageing, lifestyle modifications and resurgent diseases - In this stage, life expectancy continues to increase (up to 80-85 years). - The mortality attributed to cardiovascular diseases declines and stabilizes as a result of improved medical care and lifestyle modifications. e. Stage Five: The age of aspired quality of life, with paradoxical longevity and persistent inequities iii. Proposition Three: During the epidemiologic transition the most profound changes in health and disease patterns obtain among children and young women. iv. Proposition Four: The shifts in health and disease patterns that characterize epidemiologic transition are closely associated with the demographic and socio-economic transitions that constitute the modernization complex.

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Proposition Five: Peculiar variations in the pattern, the pace, the determinants and the consequences of population change differentiate three basic model of the epidemiologic transition: the classic or western model, the accelerated model and the contemporary or delayed model. a. Classic Western Model: It describes the gradual progressive transition from high mortality and high fertility to low mortality and low fertility, that accompanied the process of modernization in most western European societies. b. The Accelerated Model: It describes the accelerated mortality that occurred most notably in Japan. A major distinction of the accelerated model is that the period taken for mortality to reach 10 per 1,000 level was much shorter than that of classic model. c. Contemporary or delayed model: It describes the relatively recent and yet to be completed transition of most developing countries where there have been more recent declines in mortality but not in fertility rates because infant and maternal mortality rates still remain high.

Criticism of Omran’s Theory - A major critique of Omran’s ET theory is the assumption that all countries will experience similar linear progression of transmission with respect to onset and speed. However, not all countries necessarily encounter ET in the same way. - This theory is insufficiently epidemiological because its focus was the changing cause of death rather than the changing causes of patterns of illness. - It has been argued that the ET theory is ambiguous because it was developed based on western data and it is difficult to ascertain the beginning and end of the transition. - The generalizability of epidemiologic transition theory has been doubted based on the great variations in mortality trends among population subgroups. - This theory fails to grasp the global nature and historical sequence of the mortality transition as it spread. Potential Future of Epidemiologic Transition The points below outline three possible health futures as proposed by Martens (2002). These stages are imaginary (although some features already are recognizable in some countries) and are not sharply delineated- there is always a continuum. There is also the possibility that economic, political, social, or environmental crises will cause the process of transition to stagnate or reverse. i. -

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Age of emerging infectious diseases In this stage, the emergence of new infectious diseases or the re-emergence of old diseases will have a significant impact on health. A number of factors will influence the development: travel and trade, microbiological resistance, human behavior, breakdowns in health systems, and increased pressure on the environment. The prevalence of infectious diseases will increase drastically, and life expectancy will fall (as is the case in many developing countries because of AIDS). Ill health will lead to lower levels of economic activity, and countries will be caught in downward spiral of environmental degradation, depressed incomes, and bad health. Control of infectious diseases will be hampered by political and financial obstacles, and by an inability to use existing technologies. The age of medical technology To a large extent, increased health risks caused by change in lifestyle and environmental changes will be offset by increased economic growth and technology improvements in the age of medical technology.

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If no long-term, sustainable economic development occurs, increased environmental pressure and social imbalance may propel poor societies into the age of emerging infectious diseases. On the other hand, if environmental and social resources are balanced with economic growth, sustained health may be achieved.

iii. The age of sustained health - In the age of sustained health, investments in social services will lead to a sharp reduction in lifestyle diseases, and most environmentally related infectious diseases will be eradicated. - Health policies will be designed to improve the health status of a population in such a way that the health of future generations is not compromised. - Although the chance that infections will emerge is only minimal, improved worldwide surveillance and monitoring systems will mean that any outbreak is dealt with properly. - Furthermore, disparities in health between rich and poor countries will eventually disappear. Double burden of disease - Double burden of disease simply means co-existence of communicable and non-communicable diseases. - An increasing number of countries face a double burden of disease as the prevalence of risk factors for chronic diseases such as diabetes, heart diseases and cancers increase and many nations still struggle to reduce maternal and child deaths caused by infectious diseases. - Due to epidemiologic transition, non-communicable diseases, such as heart diseases, stroke, diabetes and cancer, now make up two-thirds of all deaths globally. - The control of risk factors such as tobacco use, sedentary lifestyle, unhealthy diet and excessive use of alcohol is becoming critical. - In addition, many developing countries continue to battle health issues – such as pneumonia, diarrhoea and malaria – that are most likely to kill children under the age of five. - Similar to other low and middle income countries, Nepal is facing a triple burden of diseases: communicable diseases, re-emerging diseases and an escalation of non communicable diseases. Emerging, Remerging Diseases and Existing Diseases Infectious diseases have for centuries ranked as major challenges to human progress and survival. They remain among the leading causes of death and disability worldwide. Against a constant background of established infections, epidemics of new and old infectious diseases periodically emerge, greatly magnifying the global burden of infections. Emerging infectious diseases are diseases that - have not occurred in humans before (this type of emergence is difficult to establish and is probably rare); - have occurred previously but affected only small numbers of people in isolated places (AIDS and Ebola hemorrhagic fever are examples); or - have occurred throughout human history but have only recently been recognized as distinct diseases due to an infectious agent Re-emerging, or resurging, diseases are those that have been around for decades or centuries, but have come back in a different form or a different location. Re-emerging infectious diseases are diseases that once were major health problems globally or in a particular country, and then declined dramatically, but are again becoming health problems for a significant proportion of the population (malaria and tuberculosis are examples).

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Factors responsible for emergence/ re-emergence of infections Factor Ecological changes(including those due to economic development and land use) Human demographics, behavior

International travel commerce

Technology and industry

Microbial adaptation and change Breakdown in public health measures

Examples of specific factors Agriculture; dams, changes in water ecosystems; deforestation/reforestation; flood/drought; famine; climate changes Societal events: Population growth and migration (movement from rural areas to cities); war or civil conflict; urban decay; sexual behavior; intravenous drug use; use of highdensity facilities Worldwide movement of goods and people; air travel

Globalization of food supplies; changes in food processing and packaging; organ or tissue transplantation; drugs causing immune suppression; widespread use of antibiotics Microbial evolution, response to selection in environment Curtailment or reduction in prevention programs; inadequate sanitation and vector control measures

Examples of diseases Schistosomiasis(dams); Rift Valley fever(dams, irrigation); Argentine hemorrhagic fever(agriculture); Hantaan (Korean hemorrhagic fever) (agriculture); hantavirus pulmonary syndrome Introduction of HIV; spread of dengue; spread of HIV and other sexually transmitted infections

"Airport" malaria; dissemination of mosquito vectors; rat borne hantaviruses; dissemination of O139 V. cholera Hemolytic uremic syndrome(E.coli contamination of hamburger meat); transfusionassociated hepatitis (hepatitis B, C), opportunistic infections in immune suppressed patients Antibiotic-resistant bacteria, "antigenic drift" in influenza virus Resurgence of tuberculosis; cholera in refugee camps in Africa; resurgence of diphtheria in the former Soviet Union

Examples of emerging, re-emerging and deliberately emerging infectious diseases Emerging Diseases  SARS  HIV  Cryptosporidiosis  H5N1 infleunza  Hendra Virus  Zika Virus  E coli O157:H7

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Re-emerging Diseases  MDR TB  Drug resistant malaria  Ebola hemorrhagic fever  Dengue  Yellow fever  Cholera  West Nile virus

Deliberately Emerging  Anthrax bioterrorism

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Epidemiological Overview of Major Communicable Disease as Public Health Problem in Nepal Cholera 1. Burden of disease i. Global - Researchers have estimated that each year there are 1.3 to 4.0 million cases of cholera, and 21 000 to 143 000 deaths worldwide due to cholera ii. -

South East Asia In 2015, 37% of total deaths due to cholera were from Asia.

iii. Nepal - As of Oct 2016, 152 cholera cases were confirmed by the National Public Health Laboratory since 30 June. - The majority of cases were from Lalitpur and Kathmandu. 2. Epidemiological Features: i. Causative Agent: Vibrio cholerae bacteria, sero-groups 01 and 0139 ii. -

Host Factors: lowest socioeconomic groups people without access to safe drinking water and adequate sanitation gastric achlorhydria Person with blood group O are more vulnerable to severe cholera if infected.

iii. Environment factors: - Cholera transmission is closely linked to inadequate access to clean water and sanitation facilities. - Typical at-risk areas include peri-urban slums, where basic infrastructure is not available, as well as camps for internally displaced persons or refugees, where minimum requirements of clean water and sanitation have not been met. iv. Reservoir: The main reservoir is humans. v.

Incubation Period: <1 to 5 days, commonly 2-3 days.

vi. Period of Communicability - Individuals remain infectious during period of diarrhoea and for up to 7 days after. - The carrier state may persist in a few cases for up to a few months. vii. -

Mode of Transmission: Faecal-oral route. The ingestion of food or water contaminated by faeces or vomits of an infected person. Raw or undercooked contaminated seafood.

viii. Common Clinical Features - Symptoms range from mild to moderate diarrhoea (80-90% of cases) to the severe sudden onset of profuse watery diarrhoea (rice water stool) accompanied by nausea and vomiting.

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In severe cases rapid dehydration, leading to circulatory shock and possible death. In such cases immediate fluid and electrolyte replacement is required. Severe untreated cases have a 50% mortality, but <1% fatality with the correct treatment.

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Diagnosis Stool microscopy and culture Rapid diagnostic kit can detect cholera in stool PCR for serotyping and biotyping

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Treatment and management Rapid rehydration by Intravenous route using crystalloids (Normal saline) Oral rehydration solution Doxycycline (100mg) capsule-3 capsule stat Azithromycin (500mg) - 2 tablets stat (for pregnant women and children less than 8 years old) Other antibiotics: erythromycin, tetracycline, ciprofloxacin

5. Prevention and Control - Surveillance of person who shared food and drink with a cholera patient for 5 days from last exposure. - Health education on safe water drinking, sanitation, food preparation, food preservation and food safety - Communities should be reminded of basic hygienic behaviors, including the necessity of systematic hand-washing with soap at critical times. - Water treatments - Immunization (oral cholera vaccines) Srub Typhus 1. Burden of disease i. Nepal - As of Nov 2016, a total of 707 cases of scrub typhus including 14 deaths were reported from 47 districts since July 2016. - Majority of the cases were from Chitwan and Kailali districts. 2. i. ii. -

Epidemiological Features Agent: Oriential (formerly Rickettsia tsutusgamushi), a gram negative bacterium Host factor Agricultural workers, People living in houses with shrubs/ bush nearby, and Travelers in areas with potential exposure to mice and mites, for e.g. camping, rafting, or trekking.

iii. Environment - This is found in areas with a suitable climate, plenty of moisture and scrub vegetation. - Areas like forest clearings, riverbanks, and grassy regions provide optimal conditions for the infected mites to thrive. - It occurs more frequently during the rainy season iv. Reservoir: Mites are both the vector and reservoir

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Incubation period: About 5 to 20 days (mean, 10-12 days) after the initial bite

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Mode of transmission Humans acquire the disease through the bite of an infected chigger mite. The larva is the only stage that can transmit the disease to humans. There is no human to human transmission

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Common clinical features Fever is high grade (>104 0F) and usually lasts 14 days. The site of insect bite is usually painless and a black scab is seen in 40% of cases Maculopapular rash is seen over trunk, and is seen around day 7 of fever. Profuse sweating

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3. Diagnosis: Laboratory diagnosis (total leucocytes count, thrombocytopenia, elevated liver transaminases) 4. Treatment and management - Pediatric treatment: Azithromycin for less than 8 years 500mg orally single dose - For more than 8 years: Doxycycline 2.2mg/kg orally twice daily for 3 days after resolution of fever (usually 5-10 day course) Adult treatment: Azithromycin 500mg orally single dose; or Doxycycline 100mg orally twice daily for 5 to 10 days. Pregnant women: Azithromycin 500mg orally single dose 5. -

Prevention and control Early case detection and management Wear protective clothing Insect repellents containing dibutyl phthalate, benzyl benzoate, or diethyl toluamide can be applied to the skin and clothing to prevent chigger bites. Clearing the vegetation where rats and mice live Use a suitable ground sheet or other ground cover. Clear vegetation spray insecticides on the soil to break up the cycle of transmission. Rodent control through multisectoral cooperation.

Ebola Virus 1. Burden of disease i. Global - The last outbreak in West Africa, (first cases notified in March 2014), is the largest and most complex Ebola outbreak since the Ebola virus was first discovered in 1976. - The most severely affected countries, Guinea, Liberia and Sierra Leone - A total of more than 28000 confirmed, probable and suspected cases were reported in Guinea, Liberia and Sierra Leone, with over 11000 deaths. 2. i. ii. -

Epidemiological Features Causal agent: Ebolavirus (Filoviridae family). Host factors Healthcare providers caring for Ebola patients Family and friends in close contact with Ebola patients

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iii. Environment - First Ebola outbreaks occurred in remote villages in Central Africa, near tropical rainforests - The most recent outbreak in West Africa has involved major urban as well as rural areas iv. Reservoir: Fruit bats are considered to be plausible reservoir of infection v.

Incubation period: 2-21 days

vi. Period of Communicability: - During acute illness and may be excreted in semen for 2-3 months. - There is no carrier state. vii. Mode of transmission - Person to person via contact with bodily secretions, organs and blood of infected individuals. - Transmission through handling of infected (dead and alive) fruit bats, chimpanzees, gorillas and forest antelopes has been documented. - Direct contact with the body of a deceased person infected with the virus. - Nosocomial transmission occurs frequently during outbreaks. viii. -

Common clinical features First symptoms are the sudden onset of fever fatigue, muscle pain, headache and sore throat. This is followed by vomiting, diarrhoea, rash, symptoms of impaired kidney and liver function In some cases, both internal and external bleeding (e.g. oozing from the gums, blood in the stools) Case fatality rates are between 50-90%.

3. Diagnosis - Difficult to distinguish EVD from other infectious diseases such as malaria, typhoid fever and meningitis. - Confirmation of Ebola virus infection are made using the following investigations: • antibody-capture enzyme-linked immunosorbent assay (ELISA) • reverse transcriptase polymerase chain reaction (RT-PCR) assay • electron microscopy • virus isolation by cell culture. 4. Treatment - No effective treatment is available. - Severe cases require intensive supportive care. 5. -

Prevention and control There is no vaccine against ebola haemorrhagic fever. Strict isolation of cases and strict barrier nursing techniques implemented. Prompt and safe burial of the dead Personal protective equipments to reduce human to human transmission

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Zika Virus 1. Burden of disease i. Global - 73 countries and territories have reported evidence of mosquito-borne Zika virus transmission since 2007 (67 with reports from 2015 onwards), of which: • 56 with a reported outbreak from 2015 onwards. • Seven with having possible endemic transmission or evidence of local mosquito borne Zika infections in 2016. - Since February 2016, 12 countries have reported evidence of person-to-person transmission of Zika virus 2. Epidemiological Features i. Agent: single-stranded RNA virus of the Flaviviridae family ii. -

Host factor Risks to fetus from pregnant mother Sexually active persons are at higher risk

iii. Environment - Monsoons and hot climate increases the breeding of mosquito hence the incidence rate increases with it. - Areas that favour breeding of Aedes mosquito such as artificial water containers. iv. Reservoir: Nonhuman and human primates are likely the main reservoirs of the virus v.

Incubation period: The incubation period (the time from exposure to symptoms) of Zika virus disease is not clear, but is likely to be 3-12 days

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Mode of transmission Primarily transmitted to people through the bite of an infected mosquito, mainly Aedes aegypti. Sexual transmission of Zika virus is also possible. Anthroponotic (human-to-vector-to-human) transmission occurs during outbreaks.

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Common clinical features The symptoms are similar to other arbovirus infections such as dengue Includes fever, skin rashes, conjunctivitis, muscle and joint pain, malaise, and headache. Symptoms are usually mild and last for 2-7 days. Complications: There is scientific consensus that Zika virus is a cause of microcephaly and GuillainBarré syndrome. 3. Diagnosis: - Infection with Zika virus may be suspected based on symptoms and recent history of travel (e.g. residence in or travel to an area with active Zika virus transmission). - A diagnosis of Zika virus infection can only be confirmed through laboratory tests on blood or other body fluids, such as urine, saliva or semen. 4. Treatment and management - Zika virus disease is usually mild and requires no specific treatment. - People sick with Zika virus should get plenty of rest, drink enough fluids, and treat pain and fever with common medicines.

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If symptoms worsen, they should seek medical care and advice. There is currently no vaccine available.

5. Prevention and control - Control of mosquito vector - Personal protection from mosquito bites Dengue 1. Burden of disease i. Global - Recent estimate indicates 390 million dengue infections per year of which 96 million (67–136 million) manifest clinically (with any severity of disease). - Another study, of the prevalence of dengue, estimates that 3.9 billion people, in 128 countries, are at risk of infection with dengue viruses ii. -

Nepal Till Nov 2016, a total of 1315 dengue cases including one death were reported from 30 different districts since January 2016 out of which majority of the cases were from Chitwan and Jhapa districts. Fifty-eight cases of Dengue were reported through EWARS in 2015.

2. Epidemiological Features i. Causative agent: - Dengue fever and dengue haemorrhagic (DHF) fever are caused by a flavivirus with 4 distinct serogroups (DEN- 1, DEN-2, DEN-3 and DEN-4). ii. -

Host factors Severity increases in persons with chronic diseases (bronchial asthma, sickle cell anaemia and diabetes mellitus). Children are at greater risk of dengue shock.

iii. Environmental factors - The outbreaks of DF/DHF are most likely to occur in post - monsoon period when the breeding of the mosquitoes is highest. - High temperature and high humidity prolongs the life span of the vector. - The spread of Dengue has resulted from several factors including human behaviour, climate and movement of humans. - Usually urban areas, having high population density, and large number of desert coolers, flower vases, construction sites, overhead tanks etc which promote mosquito breeding, are at high risk iv. Reservoir: Aedes mosquito. v.

Incubation period: 3-14 days, commonly 4-7 days.

vi. Period of Communicability - Patients are infective for mosquitoes from shortly before and during the febrile period. - The mosquito becomes infective 8-12 days following the blood-meals and remains infective for life (23 months).

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vii. Mode of transmission: Through the bite of an infected female Aedes mosquito. viii. Common clinical features Phases of dengue Clinical signs and symptoms Febrile phase - Skin erythema, generalized body ache, myalgia, arthralgia and headache - Sometimes, sore throat, conjunctival injection - Anorexia, nausea and vomiting are common Critical phase - Shock from plasma leakage; severe hemorrhage; organ impairment Recovery phase - Hypervolaemia 3. Diagnosis - Laboratory finding suggestive of dengue are Leucopenia, Atypical lymphocytsis, Thrombocytopenia, Hemoconcentration, raised ESR, LDH, urea and liver enzymes (ALT>AST). - Honeycomb sign in USG is specific findings. - Antigen detection test NS1 remains positive from day of fever to first week. - Antibodies (IgG/IgM) are positive at the end of first week to first few months. - Molecular technique PCR can be done during the period of positivity of NS1 antigen test 4. Treatment - Supportive and symptomatic treatment 5. Prevention and control - Control of mosquito vector - Personal protection from mosquito bites Malaria 1. i. -

Burden of disease Global In 2000, there were 106 countries and territories with ongoing malaria transmission The number of malaria cases fell from an estimated 262 million globally in 2000, to 214 million in 2015, a decline of 18%. The number of malaria deaths globally fell from an estimated 839000 in 2000, to 438000 in 2015, a decline of 48%.

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South- Asia An estimated number of malaria cases in 2015 in WHO South East Asian region were 20 million. An estimated number of malaria deaths in 2015 were 32000.

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Nepal Confirmed cases dropped from 2092 in FY 2069/70 to 1352 in 2071/72. No Malaria deaths have been recorded after 2012 till date. Ninety cases of malaria were reported through EWARS in 2015 In Nepal 54 VDC are at high risk of Malaria.

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2. Epidemiological Features i. Causative agents: Plasmodium vivax, falciprum, malariae, Ovale ii. -

Host factors Children and pregnant are more prone for malaria. Travel to endemic area within a month or residing at endemic area increases likelihood of disease.

iii. Environmental factor - Monsoons and hot climate increases the breeding of mosquito hence the incidence rate increases with it. - The mosquito prefers to bite during dusk and dawn. - The likelihood of being infected by malaria decreases when the environmental temperature remains lower than 16 0C as the parasite cannot complete life cycle in the vector. iv. Reservoir: Humans v.

Incubation period: Agent

Incubation period

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P. falciparum

6-12 days

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P. vivax P. ovale P. malariae

8-12 days 8-12 days 12-16 days

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Period of communicability: Humans may infect mosquitoes as long as infective gametocytes are present in the blood. Anopheles mosquitoes remain infective for life. Mode of transmission Transmitted by bites of infective female Anopheles mosquitoes. Injection or transfusion of contaminated blood may also transmit malaria. Congenital transmission is rare.

viii. Clinical features a. Uncomplicated malaria - The classical (but rarely observed) malaria attack lasts 6-10 hours. It consists of • a cold stage (sensation of cold, shivering) • a hot stage (fever, headaches, vomiting; seizures in young children) • a sweating stage (sweats, return to normal temperature, tiredness). - Classically, the attacks occur every second day with the "tertian" parasites (P. falciparum, P. vivax, and P. ovale) and every third day with the "quartan" parasite (P. malariae). - More commonly, the patient presents with a combination of symptoms such as fever, chills, sweats, headaches, nausea and vomiting, body aches, general malaise. b. Severe malaria - Cerebral malaria, with impairment of consciousness, seizures, coma, or other neurologic abnormalities - Severe anemia - Hemoglobinuria (hemoglobin in the urine)

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Acute respiratory distress syndrome (ARDS) Acute kidney failure Metabolic acidosis

3. Diagnosis - Rapid diagnostic test kits - Microscopic tests 4. -

Prevention and control measures Control of mosquito vector. Personal protection from mosquito bites Vaccine is recently approved Chemoprophylaxis for traveler to endemic area

Kala-azar (Visceral Leishmaniasis) 1. i. -

Burden of disease Global Annually an estimated 900,000–1.3 million new cases occur globally An estimated 200,000 to 400,000 new cases of visceral leishmaniasis occur worldwide each year.

ii. -

South East Asia The kala-azar elimination programmes in South-East Asia are making sustained progress towards elimination, and cases are declining in the three major endemic countries: Bangladesh, India and Nepal.

iii. -

Nepal 12 districts in Nepal are endemic to Kala-azar The trend of Kala‐azar cases has been decreasing significantly for the last several years. The total cases in FY 2071/72 were 220.

2. i. ii. -

Epidemiological Features Causative agent: Leishmania donovani Host factors: Males are affected twice as often as females Usually strikes the poorest of the poor Human behavior such as sleeping outside or on the ground increases risk of transmission

iii. Environmental factors - Kala-azar is mostly confined to the plains; it does not occur in altitudes over 2000 feet. - Generally, there is high prevalence during and after rains. iv. Reservoir: - There are variety of animal reservoirs e.g. dogs, jackals, rhodents and other mammals. v. vi. -

Incubation period: Generally 1 to 4 months (range is 10 days to 2 years) Mode of transmission Person to person transmission through the bite of female sandfly. Transmission of kala-azar has also been recorded by blood transfusion.

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vii. Clinical Features - The classical features are fever, splenomegaly and hepatomegaly accompanied by anaemia and weight loss. - Darkening of skin of the face, hands, feet and abdomen (black sickness) - Lymphadenopathy may also occur - Kala-azar if untreated, has a high mortality. - Post kala-zazar dermal leishmaniasis is also common 3. Diagnosis - Rapid diagnosis using Rk39 dipstick test - Serological tests 4. Treatment - Amphotericin B - Miltefosine 5. -

Prevention and control Early diagnosis an effective case management Vector control Effective disease surveillance Control of animal reservoir hosts

Lymphatic Filariasis 1. Burden of disease i. Global - 947 million people in 54 countries worldwide remain threatened by lymphatic filariasis and require preventive chemotherapy to stop the spread of this parasitic infection. - Data from World Health Organization (WHO) show that more than 556 million people worldwide were treated for lymphatic filariasis in 2015 ii. -

Nepal Sixty one districts are endemic to Lymphatic filariasis in Nepal. LF mapping in revealed 13% average prevalence of LF infection in the country, ranging from <1% to 39%.

2. i. -

Epidemiological features Causative agent Nematodes (roundworms) of the family Filariodidea. There are 3 types of these thread-like filarial worms: • Wuchereria bancrofti, which is responsible for 90% of the cases • Brugia malayi, which causes most of the remainder of the cases • Brugia timori, which also causes the disease.

ii. -

Host factors Man is a natural host All ages are susceptible. In endemic areas, filarial infection has been found even in infants aged less than 6 months.

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iii. Environmental factors - The maximum prevalence of culex mosquitoes are observed in temperature between 22 to 380C. - Lymphatic filariasis is associated with poor sanitation and bad drainage. iv. Reservoir: Humans are the only known reservoir for Wuchereria bancrofti v.

Incubation period: Clinical incubation period is 8 to 16 months

vi. Mode of transmission - Filariasis is transmitted by the bite of infected vector mosquitoes (culex). vii. -

Clinical features A large proportion of infected persons remain asymptomatic despite the presence of microfilariae. The manifestations result from either acute inflammation or chronic lymphatic obstruction. Clinical manifestations range from those without apparent clinical disease to those with lymphedema and severe disfigurement of the limbs and genitalia. Fever may or may not be present in both the acute and chronic forms. The various presentations can include lymphangitis and adenitis, funiculitis and hydrocoele, abscess formation, lymphedema and elephantiasis, chyluria.

3. 4. -

Diagnosis Blood smears- nocturnal bloods Treatment Diethyl carbamazine (DEC) Albendazole

5. -

Prevention and control Chemoprophylaxis through mass drug administration Control of mosquito vectors Personal protection measures from mosquito bite

Influenza 1. i. ii. -

Burden of disease Global In April 2009, WHO declared the emergence of human cases of H1N1 swine influenza virus. In June 2009, WHO raised the pandemic alert (phase 5 to 6) Till May 2010 more than 214 countries reported lab confirmed pandemic influenza H1N1 2009, including over 18097 deaths Between 2003-2016, total confirmed human cases of H5N1 influenza was 850 and total death of 450. SEARO Region Till May 2010, there were 1808 deaths due to pandemic H1N1 influenza. As of October 2009, in the WHO Southeast Asia region, 10 of 11 member countries have reported more than 40000 cases of H1N1 virus infection and 573 deaths. The 3 hardest hit countries in the region were Thailand, India and Indonesia.

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iii. Nepal - FirsT case of H1N1 influenza was detected in Jun 2009. - Four outbreak events of influenza with 1445 cases and 31 deaths were reported in FY 2071/72 2. i. -

Epidemiological Features Causative agent Single stranded RNA virus of Orthomyxoviridae family Three distinct types: Influenza A, B and C Influenza A is divided into different subtypes of which clinically important subtypes are • H1N1 (Swine Flu) • H5N1,(Avian Influenza) • H7N9 (novel avian influenza)

ii. -

Host factors Occurs in every age-group. Population does not have immunity to virus Complications higher in people with underlying diseases such as asthma, cardiac diseases, renal diseases and in pregnancy. Obesity has also found to predispose to severe disease

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iii. Environmental factors - Low temperature and low humidity favor aerosol transmission, explaining the seasonal nature of influenza in temperate climates. - In tropical climates influenza infections are associated with increased rainfall - The best environment for a novel virus is a population without pre-existing immunity to it, enabling it to spread pandemically iv. Reservoir: - Pigs are most important reservoir of H1N1 virus. - Aquatic birds are reservoirs for avian influenza (H5N1) v.

Incubation period: between 1 and 7 days

vi. Mode of transmission - Through droplets from coughing or sneezing, and - Through direct or indirect contact with the respiratory secretions of an infected person vii. Clinical features - Ranging from mild self-limiting upper respiratory illness to lower respiratory infection including ARDS, cardiac involvement, neurological involvement, multiorgan failure, septicemia and death. - Common features: mild respiratory illness with fever, cough, sore throat, dyspnea, rhinorrhea, myalgias, chills, headache and fatigue. - Diarrhea and vomiting are more commonly seen than with seasonal flu. - Reported complications: myocarditis, pericarditis, encephalitis, seizures, myositis, multiorgan failure and toxic shock syndrome 3. Diagnosis - Clinical diagnosis (based on acute onset of fever and cough) - Reverse-transcriptase polymerase chain reaction (RT-PCR)

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4. Prevention and control a. Non-Pharmacological Interventions - Personal protective measures • Shielding one’s mouth and nose while coughing or sneezing, • Frequently washing one’s hands with soap - Isolation and social distancing • Home quarantine • School closure and cancellation of mass gathering b. Pharmacological Interventions - Chemoprophylaxis • If the likelihood of complications is high, oseltamivir or zanamivir may be used as post-exposure chemoprophylaxis for affected individuals, especially healthcare workers - Vaccination • Vaccine against the H1N1 virus is presently available in a few countries. Tuberculosis 1. i. -

Burden Global Tuberculosis (TB) is one of the top 10 causes of death worldwide In 2015, 10.4 million people fell ill with TB and 1.8 million died from the disease. Over 95% of TB deaths occur in low- and middle-income countries In 2015, an estimated 1 million children became ill with TB and 170 000 children died of TB (excluding children with HIV). Globally in 2015, an estimated 480,000 people developed multidrug-resistant TB (MDR-TB).

ii. SEARO Region According to Global TB Report 2016 - Mortality (excluding HIV+TB) – 710,000 (37 per 100,000) - Mortality (HIV+TB only) 74000 (3.9 per 100,000) - Incidence rate (including HIV+TB)- 12 per 100,000 - Estimated MDR.RR-TB cases among notified pulmonary TB cases- 110,000 iii. Nepal According to Global TB Report 2016 - TB incidence (including HIV)- 44 per 1000 - Incidence of MDR/RR-TB – 1.5 per 1000 - TB mortality- 6.1 per thousand 2. i. -

Epidemiological features Causative agent: Microbacterium tuberculosis (gram positive bacteria) Microbacterium bovis (primarily from cattles)

ii. -

Host factors Occurs at any age Persons who are undernourished, suffering from diabetes, HIV infection or under immune suppressive drugs are more susceptible.

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iii. Environmental factors - Poor housing and overcrowding are closely associated with transmission of infection. iv. Reservoir: Primarily humans. In some areas diseased cattle, swine and other mammals are infected. v.

Incubation period: 3-8 weeks, Latent infection may be many decades

vi. Period of Communicability - As long as there are viable organisms in the sputum. - Most sputum smear positive cases stop being infectious after 2 weeks following appropriate treatment. vii. Mode of transmission - Person to person via inhalation of M. tuberculosis bacilli in droplet nuclei from coughing and sneezing. - Bovine TB is spread primarily through the ingestion of unpasteurised milk or milk products and in some cases through airborne transmission. viii. -

Clinical features Fever and night sweats Persistent cough lasting 3 weeks or more that may produce discoloured or bloody sputum. Pain with breathing or coughing (pleurisy) Weight loss Symptoms of TB disease in other parts of the body depend on the area affected.

3. -

Diagnosis Sputum smear microscopy GeneXpert MTB/RIF Culture of mycobacterium

4. Treatment - Active, drug-susceptible TB disease is treated with a standard 6 month course of 4 antimicrobial drugs under DOTS therapy 5. -

Prevention and control of TB BCG vaccination Prevention from susceptible contacts Improving housing and ventilation

DOTS Program - DOTS is one of the effective strategy of National Tuberculosis Program for tuberculosis control. - National TB Program has rapidly expanded DOTS strategy in 1996 with 4 pilot centers. - The treatment of TB by DOTS is being implemented in all 75 districts of the country since April 2001. - The expansion of this cost effective and highly successful treatment strategy has reduced TB mortality and morbidity in Nepal. - A total of 4224 DOTS treatment centers are providing TB treatment services in Nepal. - Recently DOTS-plus programme is developed by WHO to manage drug resistant TB (DR-TB) using second line anti TB drugs. - The Nepal DOTS-Plus programme for treatment of drug resistant TB is the first pilot project in South East Asia.

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Leprosy 1. Burden of Disease i. Global - The prevalence rate of the disease has dropped by 99%: from 21.1 per 10 000 in 1983 to persons to 0.24 per 10 000 in 2014. - With the exception of few small countries (with populations of less than 1 million), leprosy has been eliminated from all countries. ii. -

Nepal During the year 2071/72, a total number of 3053 new leprosy cases were detected and were put under multi drug therapy (Multi Drug Therapy). 2461 cases were under treatment and receiving MDT at the end of the fiscal year.

2. Epidemiolgical Features i. Causative Agent: Microbacterium leprae ii. -

Host factors Incidence is higher in males than in females In endemic areas, the disease is acquired commonly during childhood.

iii. iv.

Environment factors Poor housing and overcrowding are closely associated with transmission of leprosy. Humidity favours the survival of M. leprae Source of infection: multibacillary cases

v. -

Incubation period: 9 months to 20 years. The average is thought to be 4 years from tuberculoid leprosy and 8 years for lepromatous leprosy.

vi. -

Mode of transmission The exact mechanism of transmission of leprosy is not known. The disease is believed to be transmitted from cases of leprosy to healthy persons. Transmission by respiratory route is also suspected.

vii. Clinical features - Paucibacillary leprosy is a milder disease and is characterized by up to 5 hypopigmented skin macules. - Multibacillary leprosy is associated with multiple (> 5) skin lesions, nodules, plaques, thickened dermis, and frequent involvement of the nasal mucosa1 3. Diagnosis: Skin smears 4. Treatment: Multidrug therapy (comprising dapsone, rifampicin and clofazimine) 6. Prevention and control - Early detection. - Prevention of disabilities and rehabilitation for leprosy patients.

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HIV & AIDS 1. i. -

Burden of Disease Global There were approximately 36.7 million people living with HIV at the end of 2015. In 2015, 1.1 million people died from HIV-related causes globally. By end-2015, 17.0 million people living with HIV were receiving antiretroviral therapy (ART) globally.

ii.

SEARO Region

iii. -

Nepal Prevalence of HIV among FSWs is 2%, MSM &TG - 2.4%, MLM-0.3-0.6% Total people living with HIV in Nepal in 2015: 22,267 PLHIV receiving HIV care in 2015: 20,307

1. Epidemiological Features i. Causative agent: Human Immune Deficiency Virus (HIV) ii. -

Host factors Affects all ages. Most cases occur among sexually active persons aged 20-49 years. Female sex workers, MSM& TG, truckers and labour migrants are high risk groups for HIV in Nepal. Risks are higher with TB-HIV co-infection HIV can pass from infected mother to foetus

iii. Reservoir of infection: Humans iv. Incubation period: The time from HIV infection to diagnosis of AIDS has an observed range of less than 1 year to 15 years or longer. v. Mode of transmission: Mode of transmission

Risk of transmission

Contribution to total number of cases

Sexual transmission Mother to child transmission Blood transfusion Infected syringes and needles

0.01-1% 20-40% 90% <0.5

>80% 1% 3-5% 5-10%

vi. Clinical Features WHO staging of HIV a. Clinical stage I - Asymptomatic - Generalized lymphadenopathy b. Clinical stage II - Weight loss <10% body weight - Minor mucocutaneous manifestations (seborrhoeic dermatic, prurigo, fungal nail infections, oral ulcerations)

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Herpes zoster within last five years Upper RTIs

c. -

Clinical stage III Weight loss >10% body weight Unexplained chronic diarrhoea >1 month Oral candidiasis Pulmonary TB Severe bacteria infections

d. -

Clinical stage IV HIV wasting syndrome Pneumocystic carinii pneumonia Cytomegalo virus disease Lymphoma Kaposis sarcoma HIV encephalopathy

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2. Diagnosis - Serological tests such as RDTs or enzyme immune assays (EIAs) 3. Treatment - HIV cannot be treated but can be supporessed by Anti retro viral therapy (ART) 4. -

Prevention and control Use of condom HIV counseling and testing (HCT) Harm reduction for injecting drug users Prevention of mother to child transmission.

Concentrated Epidemic of HIV in Nepal Nepal’s HIV epidemic is largely concentrated in most at risk populations, especially female sex workers (FSW), IDUs, MSM, transgender and some migrants to high risk districts in India. Nepal’s HIV prevalence in general population is 0.206. The prevalence in people who inject drugs is 6.4% in Kathmandu and among female injecting drug users the prevalence is 8.8%. The prevalence of HIV within MSM and third gender is 8.2%. However, HIV is not a concentrated epidemic among FSWs in recent years. According to IBBS survey 2016, the prevalence of HIV among FSWs in highways district of terai was only 0.8% .

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Measles (Rubeola) 1. i. -

Burden of disease Global Measles is one of the leading causes of death among young children. In 2014, there were 114 900 measles deaths globally. Measles vaccination resulted in a 79% drop in measles deaths between 2000 and 2014 worldwide.

ii. -

Nepal In 2009, Nepal has had already achieved the goal of measles control. In 2014, there were only 9 cases of measles.

2. Epidemiological Features i. Causal agent: Measles virus (paramyxovirus family) ii. -

Host factors One attack provides life long immunity Affects virtually everyone in infancy or childhood- between 6 months and 3 years

iii. Environmental factors - Virus can spread in any season. - Outbreaks are more common during winter and early spring iv. Reservoir: Humans - no known animal reservoir. v.

Incubation period: 10 days from exposure to onset of fever, and 14 days after appearance of rash

vi. Period of Communicability - From 1 day before the beginning of the prodromal period until 4 days after the appearance of rash. vii. Mode of transmission: Directly from person to person mainly by droplet infection and droplet nuclei viii. Clinical features - Prodromal illness with high fever, coryza, respiratory infection, conjunctivitis and Koplik's spots in the mouth. - Characteristic rash (raised red blotches) appears on the 3-7th day, initially on the face and then becoming generalized lasting 4-7 days. - An estimated 20% of measles cases experience one or more complications including otitis media, pneumonia, corneal scarring, croup, diarrhoea and encephalitis. 3. Diagnosis - Commonly diagnosed with signs and symptoms - Serological tests 4. -

Prevention and control Routine MMR vaccination Catch up, keep up and follow up campaign. Case based surveillance

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Rubella(German Measles) 1. Epidemiological Features i. Agent: RNA virus of Toga virus family ii. -

Host factors Mainly a disease of childhood particularly 3 to 10 years. One attach provides life-long immunity Infants of immune mothers are protected for 4-6 months.

ii. -

Environmental factors Disease usually occurs in a seasonal pattern i.e. in temperate zones during the late winter and spring.

iii. iv. v. -

Reservoir: Humans Incubation period: 2-3 weeks, average 18 days Period of Communicability From 1 week before the onset of rash to 1 week after the onset of rash.

vi. Mode of transmission: - Person to person via airborne transmission or droplet nuclei. - Also direct contact with nasopharyngeal secretions of an infected person. Vertical transmission leading to congenital rubella syndrome (CRS) viii. Common clinical features - A mild viral illness. Children may develop few or no symptoms. - Infection with rubella among adults is characterized by mild fever, sore throat, conjunctivitis, headache, joint aches for 2-3 days followed by a maculopapular rash, which lasts about 3 days. - Swollen lymph glands around the ears and back of head. - Up to 50% of rubella infections are subclinical. 2. Diagnosis - Virus isolation and serological tests 3. Prevention and control - Routine MMR vaccination Typhoid Fever 1. Epidemiological Features i. Causative agent: Salmonella typhii ii. -

Agent factors All cases are susceptible to infection More cases are reported among males than females.

iii. Environmental factors - The peak incidence is reported during rainy season. - Pollution, open air defecation, low food and personal hygiene favour transmission.

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iv. Reservoir: Man is the only known reservoir of infection v.

Incubation period: Usually 10-14 days

vi. Modes of transmission - Feaco-oral route or urine-oral route - Ingestion of contaminated water, milk and/or food through flies vii. Clinical features - The acute illness is characterized by prolonged fever, headache, nausea, loss of appetite, and constipation or sometimes diarrhoea. - Symptoms are often non-specific and clinically non-distinguishable from other febrile illnesses. - However, clinical severity varies and severe cases may lead to serious complications or even death. 2. Diagnosis - Culture isolation of organisms 3. Prevention and control - Safe food hygiene practices, especially among overseas travellers. - Immunization is recommended for some overseas travellers and some occupations. Epidemiological Overview of Major Non-Communicable Disease as Public Health Problem in Nepal Atherosclerosis -

Atherosclerosis, a disease of the large arteries, is the primary cause of heart disease and stroke. Atherosclerosis is a leading cause of vascular disease worldwide. Its major clinical manifestations include ischemic heart disease, ischemic stroke, and peripheral arterial disease.

i. -

Disease burden of Athrosclerosis In westernized societies, it is the underlying cause of about 50% of all deaths In high-income countries, there have been dramatic declines in the incidence and mortality from ischemic heart disease and ischemic stroke since the middle of the 20th century. For example, in the United Kingdom, the probability of death from vascular disease in middle-aged men (35-69 years) has decreased from 22% in 1950 to 6% in 2010. Most low- and middle-income countries have also reported declines in mortality from stroke over the last few decades, but mortality trends from ischemic heart disease have been more varied, with some countries reporting declines and others reporting increases (particularly those in Eastern Europe and Asia).

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ii.

Risk Factors of Atherosclerosis a. Major Risk Factors - Unhealthy blood cholesterol and lipoprotein levels - High blood pressure - Smoking - Insulin resistance

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Diabetes Overweight or obesity Lack of physical activity Unhealthy diet Older age Family history of early heart disease

b. -

Emerging risk factor High levels of C-reactive protein (CRP) Triglycerides Sleep apnea Stress Alcohol

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Process of Atherosclerosis Fatty streaks formation Atheroma formation Atherosclerotic plaques formation

Prevention and control - Modifying risk factors: blood-pressure, smoking, serum lipids - Improving dietary practices, increased exercise and smoking cessation - Lipid-lowering pharmacoptherapy - Antihypertensive medication Road Traffic Accidents Burden of RTAs - Road traffic injuries are currently estimated to be the ninth leading cause of death across all age groups globally. - About 1.25 million people die each year as a result of road traffic crashes. - 90% of the world's fatalities on the roads occur in low- and middle-income countries - Road Traffic Accident (RTA) is one among the top five causes of morbidity and mortality in SouthEast Asian countries. - According to the latest WHO data published in may 2014 Road Traffic Accidents Deaths in Nepal reached 5,036 or 3.18% of total deaths. Risk Factors/ Determinants for Road Traffic Accidents i. Human Factors - Drunken driving - Driver fatigue - Over speeding - Overloading ii. Poor road conditions iii. Poor vehicle conditions

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Prevention and control i. Improving condition of vehicles - Well-maintained brakes, lighting, tyres, etc. - Vehicles with seat belts and other necessary safety provisions (like airbags). ii.

Improving conditions of road

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Well maintained roads with frequent relaying of road surfaces and markings of road safety signs. Footpaths for pedestrians and pedestrian crossings at intersections. Provision of separate lanes for slow-moving and fast-moving vehicles. Widening of roads and junctions

iii. -

Reducing accidents by human factors Driver and pedestrian awareness campaigns Medical checkup and screenings programs for vision and hearing Trainings on first aid

iv. -

Legislation measure Strict implementation of rules for wearing helmets and seat belts. Enforcement of traffic rules. Strict monitoring and standardization of licensing

Diabetes Diabetes is a chronic disease that occurs either when the pancreas does not produce enough insulin or when the body cannot effectively use the insulin it produces. Disease burden of diabetes - The global prevalence of diabetes among adults over 18 years of age has risen from 4.7% in 1980 to 8.5% in 2014. - Diabetes prevalence has been rising more rapidly in middle- and low-income countries. - In 2012, an estimated 1.5 million deaths were directly caused by diabetes and another 2.2 million deaths were attributable to high blood glucose. - According to STEPS survey 2013, the prevalence of diabetes mellitus in Nepal, based on plasma venous value of blood glucose and including those on medication, was 3.6%. Types of diabetes i. Type 1 diabetes - Type 1 diabetes (previously known as insulin-dependent, juvenile or childhood-onset) is characterized by deficient insulin production and requires daily administration of insulin. - The cause of type 1 diabetes is not known and it is not preventable with current knowledge. - Symptoms include excessive excretion of urine (polyuria), thirst (polydipsia), constant hunger, weight loss, vision changes and fatigue. These symptoms may occur suddenly. iii. Type 2 diabetes - Type 2 diabetes (formerly called non-insulin-dependent or adult-onset) results from the body’s ineffective use of insulin.

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Type 2 diabetes comprises the majority of people with diabetes around the world , and is largely the result of excess body weight and physical inactivity. Symptoms may be similar to those of Type 1 diabetes, but are often less marked. As a result, the disease may be diagnosed several years after onset, once complications have already arisen.

Risk Factors - Physical inactivity/ sedentary behaviour - Hypertension - Smoking and alcohol consumption Consequences - Adults with diabetes have a 2-3-fold increased risk of heart attacks and strokes. - Combined with reduced blood flow, neuropathy (nerve damage) in the feet increases the chance of foot ulcers, infection and eventual need for limb amputation. - Diabetic retinopathy is an important cause of blindness, and occurs as a result of long-term accumulated damage to the small blood vessels in the retina. 2.6% of global blindness can be attributed to diabetes. - Diabetes is among the leading causes of kidney failure Prevention and control - Dietary modification: Avoiding sugar and saturated fat intake - Avoiding tobacco use - Increasing physical activity - Maintaining healthy body weight Prevention, Control and Management of Communicable and Non-communicable Diseases Prevention and control strategies for Kala-azar i. Improve program management ii. Early diagnosis and complete treatments iii. Integrated vector management iv. Effective disease and vector surveillance v. Social mobilization and partnerships vi. Clinical, implementation and operational research Prevention and control strategies for Filariasis i. Interruption of transmission by yearly Mass Drug Administration using two drug regimens (DiethylcarbamazineCitrate and Albendazole) for six years. ii. Morbidity management by self-help and with support using intensive but simple, effective and local hygienic techniques. Prevention and control strategies for Dengue i. Early case detection, diagnosis , management and reporting of the DF,DHF & DSS ii. Regular monitoring of DF/DHF/DSS cases and surveillance through the EWARS iii. Mosquito vector surveillance in different municipalities. iv. Integrated vector control approach

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SOCIAL EPIDEMIOLOGY Concept, Scope and Process Social Epidemiology is defined as the branch of epidemiology that considers how social interaction and collective human activities affect health. In other words, social epidemiology is about how a society’s innumberable social arrangements, past and present, yield different exposures and thus differences in health outcomes among the persons who comprise the population. Berkman and Kwachi defined social epidemiology as the branch of epidemiology that studies the social distribution and social determinants of states of health. - Social epidemiology focuses particularly on the effects of socio-structural factors on states of health The major premise of social epidemiology is that each society forms its own distribution of health and disease. In other words, social epidemiology assumes that the distribution of health and disease in a society reflects the distribution of advantages and disadvantages in that society. Based on this premise, social epidemiology examines which socio-structural factors affect the distribution of health and disease, as well as how these factors influence individual and population health. - Examples of socio-structural factors include  Social class  Gender  Ethnicity  Discrimination  Social network  Social policy  Income distribution Importance of Social Epidemiology As a medical science, social epidemiology has been important for four reasons i. First, it is way to elucidate the complexity of causation in diseases that are not accounted for by single agents or simple processes (for example heart disease) ii. Second, even when pathogenic agents and processes are well recognized, it may be a means of identifying other elements in a network of determinants that together constitute sufficient cause, particularly elements for which intervention may be most practicable. Thus factors governing shoewearing are important in hookworm control. iii. Third, it may guide interventions that improve health generally, not simply by lowering rates of specific diseases. iv. Finally, social epidemiology may be a key to a non-reductive pathology, which recognizes the important interactions between milieu, a sense of self, and somatic state. History of Social Epidemiology - Although Social Epidemiology is a newer concept, the idea that social conditions influence health is not new. Ever since John Graunt (1662) counted deaths in county parishes in England in the seventeenth century, social variations in morbidity and mortality have been observed. - By the nineteenth century, physicians such as Villerme (1830) and Virchow (1848) refined observations identifying social class and work conditions as crucial determinants of health and disease - Durkheim wrote eloquently about another profound social experience that of social integration and how it was related to patterns of mortality, especially suicide.

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In a seminal article, Saxon Graham (1963) discussed the social epidemiology of selected chronic illnesses. While never giving an explicit definition of social epidemiology, he suggested that a union of sociology with the medical sciences would produce a new and more successful epidemiology. In 1969, Leo G Reeder presented a major address to the American Sociological Association called “Social Epidemiology: an Appraisal”. He defined social epidemiology as the ‘study of the roles of social factors in the aetiology of dieases’. At the end of 19th century, Germ Theory established germs as the major cause of disease. Major epidemiologic studies were concentrated on identifying new germs that cause diseases and social factors affecting health were overshadowed. Later in early 20th century, the idea that disease is caused by exposure to multiple individual risk factors (called web of causation) entered the mainstream of epidemiological theories. By the 1980s, several epidemiologists developed social epidemiology, underscoring the importance of socio-structural factors on health.

Theories of Social Epidemiology There are three main theories used in social epidemiology i. Psychosocial theory ii. Social Production of Disease/ Political Economy iii. Ecosocial theory i. -

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ii. -

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Psychosocial Theory A psychosocial theory views health outcomes as functions of host-agent-environment interactions (i.e., impact of social environment to host resistance to disease). Although socio-structural constructs such as dominance hierarchies, material deprivation, victimization, and social isolation are identified as fundamental social determinants, the chronic stress produced by these determinants and effect of chronic stress on the individual biological defenses is viewed as the intervening mechanism of host-pathogen susceptibility. Richard Wilkinson states that the lower levels of social cohesion, trust, and social support that are prevalent in hierarchical societies promote both material deprivation and a pathogenic quality of social relationships that have direct effects on an individual’s defenses against a wide array of diseases. Biological responses to stress-inducing situations are ameliorated by the strength of the social support provided by other people as being important by the individual. Social Production of Disease/ Political Economy The main foci of this theory are on the various structural determinants of health that are linked to disparities in social and economic power, such as poverty, detrimental working conditions, and spatial isolation from health care. An important variant of this perspective places emphasis on disease as an outcome of a production function that serves the interest of the dominant social classes. It focuses on class inequalities in health within and between countries. Some implications for action suggested by this theory are:  Strategies for improving population health require a vision of social justice  Lack of concerns about social equity, economic growth and public health interventions may end up aggravating social inequalities in health if the economic growth exacerbates economic inequality.  Social epidemiologists must be key actors in ensuring viability of the vital public health activity of monitoring social inequalities in health.

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iii. Ecosocial Theory - First proposed by Nancy Krieger in 1994, it is a broad and complex theory integrating biologic and social reasoning along with ecological perspective to address population distributions of disease and social inequalities in health. - Ecosocial theory incorporates and contextualizes the basic principles and processes of the social production of disease model within the framework of an ecological analysis. - Ecosocial theory is built around four central concepts  Embodiment  Pathways to embodiment (means of incorporation)  Cumulative interplay between exposure, susceptibility and resistance  Accountability and agency - In essence, these four central constructs function as heuristic lenses through which social epidemiologists can unveil and illuminate the patterns of health and disease that are a function of the complex interrelationships between the biological and social aspects of causality. Summary: • In contemporary social epidemiology, the three main theoretical frameworks for explaining disease distribution are i) Psychosocial, 2) Social production of disease/ political economy of health, and 3) eco-social theory. • A psychosocial framework directs attention to endogenous biological responses to human interactions; a social production of disease/ political economy of health framework explicitly addresses economic and political determinants of health and disease but leave biology opaque; ecosocial theory seeks to integrate social and biological reasoning and a dynamic, historical and ecological perspective to develop new insights into determinants of population distribution of disease and social inequalities in health. Social Determinants of Health The social determinants of health (SDH) are the conditions in which people are born, grow, work, live, and age, and the wider set of forces and systems shaping the conditions of daily life. These forces and systems include economic policies and systems, development agendas, social norms, social policies and political systems. (WHO) Some of the important social determinants of health are described below i. Social gradient - Poor social and economic circumstances affect health throughout life. - People further down the social ladder usually run at least twice the risk of serious illness and premature death as those near the top - It can include having few family assets, having a poorer education, having insecure employment, living in poor housing, living up on an inadequate retirement pension, etc. - The longer people live in stressful economic and social circumstances, the greater the physiological wear and tear they suffer and less likely they are to enjoy a healthy aging. ii. -

Social exclusion Poverty, relative deprivation and social exclusion have a major impact on health and premature death, and the chances of living in poverty are loaded heavily against some social groups. The un unemployed, many ethnic minorities, disabled groups, refugees people are at particular risk.

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Social exclusion results from racism, discrimination, stigmatization, hostility and unemployment. Social exclusion increases the risks of divorce and separation, disability, illness, addiction and deprivation to basic health services.

iii. Work and Employment - In general, having a job is better for health than having no job. - But the social organization of worl, management styles and social relationships in the workplace all matter for health. - Having little controlover one’s work is particularly related to an increased risk of low back pain,sickness and occupational diseases. - Further job insecurity has shown to increase effects on mental health (depression), heart disease and self-reported ill health. iv. Food - A good diet and adequate food supply are central for promoting health and well-being. - A shortage of food and lack of variety causes malnutrition and deficiency diseases. - In many countries, the poor tend to substitute cheaper processed foods for fresh food. High fat intake often occur in all social groups. - People on low incomes, such as young families, elderly people and the unemployed, are least able to eat well. v. -

Addiction Drug use is both a response to social breakdown and an important determinant in worsening the resulting inequalities in health. - Alcohol dependence, illicit drug use and cigarettes smoking are all closely associated with markers of social and economic disadvantage. - Addiction are associated to health risks, accidents, violence, poisonoing, injury and suicide. vi. Stress - Social and psychological circumstances can cause long-term stress. - Continuing anxiety, insecurity, low self-esteem,social isolation and lack of control over work and home life have powerful effects on health. - Long term stress makes people vulnerable to a wide range of conditions including, diabetes, high blood pressure, heart attack, stroke, depression and aggression. vii. Culture - All cultures have systems of health beliefs to explain what causes illness, how it can be cured or treated, and who should be involved in the process. - Cultural issues play a major role in determining a person's health or the health of a community as a whole.

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Evidence Based Public Health Practice Evidence based public health can be defined as the conscientious, explicit and judicious use of current best evidence in making decisions about the care of communities and populations in the domain of health protection, disease prevention, health maintenance and improvement (health promotion). - Jenicek, 1997 - For public health professionals, evidence is some form of data, including epidemiologic (quantitative) data, results of program or policy evaluations, and qualitative data- for uses in making judgments or decisions. - Public health evidence is usually the result of a complex cycle of observation, theory or experiment. Characteristics of evidence based public health (EBPH) - Making decisions using the best peer-reviewed evidence (both quantitative and qualitative research) - Using data and information systems systematically - Applying program-planning frameworks (that often have a foundation in behavioural science theory). - Enagaging the community in assessment and decision making - Conducting sound evaluation, and - Disseminating what is learned to key stakeholders and decision makers Importance of evidence based public health - It provides assurance that decision making is based on scientific evidence and effective practices. - It helps to ensure the retrieval of up-to-date and reliable information about what works and doesn’t work for a particular public health question - It provides assurance that one’s time is being used most efficiently and productively in reviewing the best of the best evidences available on the particular public health question. Level of scientific evidence in evidence based public health practice Category How established Data source examples Evidence based Peer review via systematic or - Community guide narrative review - Cohchrane reviews - Narrative reviews based in published literature Effective Peer review - Articles in the scientific literature - Research tested intervention programs - Technical reports with peer review Promising Written program evaluation - Government reports (without peer review) without formal peer review - Conference presentations Emerging Ongoing work, practice based - Pilot studies summaries, or evaluation works - Projects funded by health foundation in progress

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Distinction between Evidence Based Public Health (EBPH) and Evidence Based Medicine (EBM) Basis of difference Type of evidence

Evidence collection

Heterogenity in decision making

Evidence Based Public Health (EPPH)

Evidence Based Medicine (EBM)

- Public health interventions usually rely on cross-sectional studies, quasiexperimental designs, and time series analyses. - These studies sometimes lack comparison group and require more caution when interpreting the results. - Generating evidences from large community based trials can be more expensive to conduct than randomized experiments in a clinic. - Population based studies generally require a large period between intervention and outcome (smoking exposure to development of lung cancer). - Public health relies in a variety of disciplines. - Fewer than 50% public health workers have any formal training in a public health discipline. This high level of heterogeneity means that multiple perspectives are involved in decisionmaking process

- Medical studies of pharmaceuticals and procedure often rely on randomized controlled trials of individuals, the scientifically rigorous of epidemiological studies

- The treatment of a medical condition (e.g. antibiotic for symptom of pneumonia) is likely to produce effects in days or weeks, or even a surgical trial for cancer with endpoints of mortality within a few years. - So, the evidences are generated relatively faster and conveniently than in public health - Medicine is more structured and formalized and therefore decision making process is relatively homogenous

Critical Appraisal of Research Article The overall goal of a research critique is to formulate a general evaluation of the merits of a study and to evaluate its applicability to public health practice. A research critique goes beyond a review or summary of a study and carefully appraises a study’s strengths and limitations. The critique should reflect an objective assessment of a study’s validity and significance. A research study can be evaluated by its component parts, and a thorough research critique examines all aspects of a research study. Some common questions used to guide a research critique include:

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Elements of critique Position of Author Study Title Description of the Study

© Prabesh Ghimire

Common questions that needs to be reviewed -

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Does the researcher’s qualifications/position indicate a degree of knowledge in the field of study? Is the title clear and unambiguous? What was the purpose of the research? Why is the problem significant/important? Identify the research questions, objectives, or hypothesis(es)

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4

Literature Review

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Conceptual Framework

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Sampling

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Methods and Design

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Analysis

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Results

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Conclusions and recommendations

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Public Health Significance and Applications

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Does the literature review seem thorough? Does the review include recent literature? Does the content of the review relate directly to the research problem? Evaluate the research cited in the literature review and the argument developed to support the need for this study. Does the research report use a theoretical or conceptual model for the study? Does the model guide the research and seem appropriate? How did it contribute to the design and execution of the study? Are the findings linked back to the model or framework? Are the size and key characteristics of the sample described? Is the sampling method appropriate? Were the participants suitable for informing research? How representative is the sample? Are the study methods described? How were the data collected? Are the data collection instruments clearly described? Were the instruments appropriate measures of the variables under study? Describe and evaluate the validity and reliability of the instruments How were the data analyzed? Do the selected statistical tests appear appropriate? Is a rationale provided for the use of selected statistical tests? What were the findings of the research? Are the results presented in a clear and understandable way? Discuss the interpretations of the study by the authors Are the interpretations consistent with the results? Are study limitations addressed?

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Were the conclusions accurate and relevant to the problem the authors identified? Were the authors’ recommendations appropriate?

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How does the study contribute to the body of knowledge? Discuss implications related to practice/education/research What additional questions does the study raise?

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Applied Epidemiology

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