UNDERSTANDING RABIES
By
Dr. A. K. Gupta From Association for Prevention an !ontro" of Ra#ies in Inia
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irst published! "arch #$%&
Author! Dr. A.K. Gupta
All rights reserved with ' Dr. A.K. Gupta
(rice!
(ublished by! Aditi (ublications ) *%+-, Ashok ihar, (hase*#, Delhi*%%$$# /0ndia1 Tel.! $23%%$4# 5*mail! guptanift6gmail.com
This book is dedicated to all those who are working together to make Rabies history
!ontents Preface Ac$no%"e&ments
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5pidemiology 7abies statistics in 0ndia 7abies irus Animal reservoirs Transmission "odes of e9posures (athogenesis 5ssentials of 7abies Diagnosis Types of 7abies :linical features of 7abies in ;umans Detection of rabies virus About arious available tests Differential Diagnosis "anagement of Animal )ites (ost 59posure (rophyla9is /(5(1
bservation of biting animal Anti 7abies accination /A71 ;istorical Development of 7abies accines 0deal 7e?uirements of a 7abies accine arious types of modern anti*rabies vaccines @indow period accine potency and storage accination in special medical conditions )ite by a vaccinated dog (5( accination chedule /@;> 55N*0"1 7easons for 7abies (ost*59posure (rophyla9is ailures 0ntradermal accination /0D71 in 0ndia
i iii
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"ode of action 0D inBection techni?ue 0D7 vaccines ide effects Dose and chedule of 0D7 5ight*site intradermal regimen /C3$4$%%E regimen1 ites for 0D7 :ontraindications to 0D7 (otency of 0D7 :riterion for protection /eroconversion1 and its importance 7abies 0mmunoglobulin /70G1 0mportance of 70G Types of 70Gs Dosage of 70Gs Availability of different 70Gs in 0ndia @hen to administer 70Gs (recautions to be taken while administering 70Gs kin ensitivity Testing F interpretation Adverse reactions to ;70Gs "ode of Administration of full dose of 70Gs 70Gs in re*e9posure cases Approach to a patient re?uiring 70Gs, when none is available 0mportant :onsiderations (re*e9posure vaccination /(r51 7abies in animals :ontrol of rabies in dogs accines for veterinary use Animal birth control "yths about rabies in 0ndia easonal variation in dog bite cases ;ow :an ou (revent 7abies "ethods of euthanasia/for animals1 :onclusion
#8 #8 #8 ##3 #3 #3 #3 #2 #2 &$ &$ &% &% &% &% &# &# && &4 &4 & & &8 &&3 &3 &3 &3 &2 &2 &2 4$
Preface 7abies is acute viral encephalitis. 0t is a =oonotic disease /i.e. transmitted by animals1. All mammals, but mainly carnivores and bats, are susceptible and can transmit rabies virus. ;uman e9posures are most fre?uently associated with bites by rabid dogs and transmission of virus from dogsH saliva. 7abies is the only communicable disease of man that is practically %$$I fatal even today but easily preventable. Till date only seven survivors have been recorded. ew countries are free of rabies as a result of their privileged geographical situation F strict application of stringent legislation. The Association for the (revention and :ontrol of 7abies in 0ndia /A(:701 reported in #$$4 that there were #$,8 reported human deaths over the period of one year. True incidence of human rabies could be even %$ times more than those officially reported. :urrent statistics of animal bites+rabies in animal population are scanty, unreliable and controversial due to poor surveillance+reporting system. Dog is the commonest source of human rabies in Asia and Africa. 0t causes over 22I of all global human rabies deaths. Nearly 28I of cases are due to bites from stray, ownerless, dogs. 4$*8I of dog bite victims are children J% years. ;ydrophobia and aerophobia are pathognomonic for rabies and occur in $I of patients. Attempting to drink or having air blown in the face produces severe laryngeal or diaphragmatic spasms and a sensation of asphy9ia. This may be related to a violent response of the airway irritant mechanisms. 5ven the suggestion of drinking may induce hydrophobic spasm. ;ydrophobia is typically uni?ue to human beings. There is no specific treatment for clinical rabies. Key to survival after e9posure to rabies virus is administration of post*e9posure prophyla9is /(5(1 as soon as possible. Death is virtually inevitable once clinical signs develop. "edical management is supportive and palliative. 7abies can be prevented by! * Avoiding contact with unfamiliar animals. Do not handle, feed, or attract wild animals. (lace litter in closed garbage cans. Never adopt or bring wild animals into your home. Teach your children to never handle unfamiliar animals, wild or domestic, even if they appear friendly.
i
* )eing a responsible pet owner. Keep rabies vaccinations up*to*date for all cats and dogs. Neuter your pets to help reduce the number of unwanted pets that may not be properly cared for or vaccinated regularly.
%-th "arch, #$%&
Dr. A. K. Gupta
:linic! : %+%, 7ana (ratap )agh, Delhi*%%$$$-, 0ndia. 7esidence! )*%+-, Ashok ihar, (hase*#, Delhi*%%$$#, 0ndia. Aut'or of /%1 7A)05 * the worst death /#1 Cre?uently Asked Luestions on 7abiesE /&1 Mnderstanding 7abies (oint Secretary, Association for (revention and :ontrol of 7abies in 0ndia /A(:701 "! $23%%$4#, E)mai"! guptanift6gmail.com *e#site! www.drakgupta.in
ii
Ac$no%"e&ments The help of my wife Dr. Archana Gupta in preparation of the manuscript is sincerely acknowledged. The publication of this book was made possible by the personal and sincere efforts of "r. Abhinav K. Gupta. 0 gratefully acknowledge Aditi (ublications for publishing this book. inally, readers are welcome to give their comments, suggestions, and feedback for improving on this effort and add to the present knowledge of rabies prevention.
Dr. A.K. Gupta
iii
Understanding Rabies Rabies
Epiemio"o&y 7abies is one of the oldest and most feared =oonotic diseases, and has been a threat to human health for more than 4$$$ years. 7abies is a neglected and severely under*reported disease. T'e *+, estimate t'e annua" num#er of 'uman ra#ies eat's to #e #et%een -/ an 0/ . All mammals, but mainly carnivores and bats, are susceptible and can transmit rabies virus. ;uman e9posures are most fre?uently associated with bites by rabid dogs and transmission of virus from dogsH saliva. The Association for the (revention and :ontrol of 7abies in 0ndia 1AP!RI2 estimated in #$$4 that in Inia, there were 3/454 reported human eat's every year. ;uman rabies in 0ndia accounts to &8 I of global rabies deaths and 8 I of human rabies deaths in Asia. 7abies is the only communicable disease of man that is practically 67 fata" even today but easily preventable. About half of the worldHs population lives in areas in which rabies is en=ootic. Till date only seven survivors have been recorded. These patients survived not due to any specific anti*rabies therapy but following intensive life support and e9cellent nursing care. These patients survived for variable periods with residual neurological deficits. All the survivors had paralytic form of rabies and maBority had history of some anti*rabies vaccination in the past. There are about 2 countries that do not report rabies. ew countries are free of rabies as a result of their privileged geographical situation F strict application of stringent legislation. According to :enters for Disease :ontrol and (revention, :ountries and political units that reported no indigenous cases of rabies are! REGI,N
!,UNTRIES
Africa
:ape erde,
Americas
North! )ermuda, t. (ierre and "i?uelon :aribbean! Antigua and )arbuda, Aruba, The )ahamas, )arbados, :ayman 0slands, Dominica, Guadeloupe, Qamaica, "artini?ue, "ontserrat, Netherlands Antilles, aint Kitts /aint :hristopher1 and Nevis, aint
1
Understanding Rabies Rabies
REGI,N
!,UNTRIES
Asia an t'e ;ong Kong, Qapan, Kuwait,
Austria, )elgium, :yprus, :=ech 7epublic,# Denmark,# inland, Gibraltar, Greece, 0celand, 0reland, 0sle of "an,
Europe
9
,ceania % #
&
:ook 0slands, iBi, rench (olynesia, Guam, ;awaii, Kiribati, "icronesia, New :aledonia, New Realand, Northern "ariana 0slands, (alau, (apua New Guinea, amoa, and anuatu
)at rabies may e9ist in some areas that are reportedly free of rabies in other mammals. )at lyssaviruses are known to e9ist in these areas that are reportedly free of rabies in other mammals. "ost of (acific >ceania is reportedly rabies*free.
Ra#ies statistics in Inia •
•
•
•
5ach year appro9imately - million people undergo post e9posure rabies treatment after a dog bite. )esides, there is an estimated 60.- mi""ion anima" #ites annually in 0ndia. "aBority /-I1 of animal bite victims belong to poor or low*income group. The Association for the (revention and :ontrol of 7abies in 0ndia 1AP!RI2 reported in #$$4 that there were 3/454 reported human eat's over the period of one year. True incidence of human rabies could be even %$ times more than those officially reported. :urrent statistics of animal bites+rabies in animal population are scanty, unreliable and controversial due to poor surveillance+reporting system. Nearly :57 of cases are due to bites from stray/ o%ner"ess/ o&s. -)547 of o& #ite victims are c'i"ren ;64 years . :hildren are at a
significant higher risk of getting bitten by a provoked bite. :hildren do not recogni=e the angry or defensive behavior of the dog and continue to play with them which the dog considers as the invasion of territory and may incite an attack. 0n 0ndia the islands of Andaman and Nicobar and
2
Understanding Rabies Rabies
Ra#ies virus
7abies is acute viral encephalitis cause #y a 7NA virus /Genus!
%$$*4&$ nm in length. Nuc"eic aci! ingle*stranded, linear, negative*sense 7NA genome, S%%.2 kb in
length. These viruses have a phospholipids envelope with glycoprotein surface spikes. The rabies virus &enome encodes five proteins! the nucleoprotein /N1, the matri9 protein /"1, the glycoprotein /G)protein is an antigen, to which protective anti*bodies are induced1, the phosphorylated protein /(1 and a large polymerase protein /<1. The e9istence of lyssaviruses that are closely related to rabies virus and that can also cause clinical disease /Duvenhage virus,
There are mainly t%o types of rabies virus. %. Street virus which is viru"ent, having a long and variable incubation period of about & weeks to & months. @hen first isolated from natural human or animal hosts, rabies virus preserves its natural properties and is referred to as street virus. "ost of the street virus isolates generally cause a lethal :N infection. #. Fi>e virus which is an attenuated street virus. 0t is a rabies virus that has been passaged in tissue culture or animals. The term fi9ed indicates only that the incubation period and virulence has been stabili=ed. i9ed virus is "east viru"ent, and has a fi>e s'ort incu#ation perio of *2 days. 0t is used as seed virus for manufacturing rabies vaccines. 7abies virus gets inactivated by! • • •
•
)y heat /% hour at $:1 >n e9posure to ultraviolet radiation )y e9posure to -$I ethanol, phenol, formalin, trypsin, U*propiolactone, %I sodium ;ypochlorite, #I glutaraldehyde Detergents 3
Understanding Rabies Rabies
• • •
•
)y lipid solvents. At p; below & or above %%. 7abies virus is susceptible to sunlight and desiccation. 0t is inactivated rapidly in sunlight and does not survive for long periods out of the host /in dried blood and secretions1 Mltra*violet and 9*rays.
7abies virus is resistant to cold and free=e drying. Anima" reservoirs Reservoir means species in which transmission of virus is sustaine with a
maintained circle of infection within the species.
7abies e9ists in t%o forms! %. Ur#an Ra#ies, propagated chiefly by unimmuni=ed dogs. #. Sy"vatic ra#ies, propagated by skunks, fo9es, raccoons, mongooses, wolves, bats etc. Dog is the commonest source of human rabies in Asia and Africa. 0t causes over 22I of all global human rabies deaths. 0n America, north of "e9ico and in 5urope, only $.%I to I of the total number of animal rabies cases reported annually involve dogs. 0n these areas, three factors may account for the low prevalence of disease in dogs! %. A large proportion of the dog population is restricted in movements /i.e., dogs are kept indoors or in enclosures and are kept on a leash when outside1 #. Dog vaccination is strongly recommended or even compulsoryV and &. 0t is possible that strains of virus that are adapted to wild species are not well suited for propagation within dog populations. The host animals of the rabies virus differ among regions. The main vectors are fo9es in 5urope and :anada, raccoons, skunks, and fruit*eating and insectivorous bats in the Mnited tates, dogs in Asia, mongooses, Backals, and dogs in Africa, and dogs and vampire bats in
4
Understanding Rabies Rabies
In Inia/ the animals commonly responsible for transmission of rabies are o&s an cats /2-I1 followed by wild animals like mongoose, fo9es F Backals /#I1
and occasionally by horses, donkeys, monkeys, cows, goats, sheep and pigs. 0ndia has appro9imately # million dogs, with an estimated dog! man ratio of %!&8.#. The dogs fall into 4 broad categories! pets /restricted and supervised1V family dogs /partially restricted, wholly dependent1V community dogs /unrestricted, partially dependent1V and undomesticated stray dogs /unrestricted, independent1. "ost dogs in 0ndia, perhaps 3$I, would fall into the last & categories. The maBority of the stray dog population is found in rural areas. Animal bites are very common in 0ndia. The annual incidence of animal bites is high, %.-I and it is more in rural areas /%.3I1, children /#.8I1 and poor+low income group /-I1. The main biting animal is dog /2%.I1, mostly stray /8&I1, followed by cat /4.-I1. Neither the age nor the breed or se9 of the dog is important in transmission of rabies. In Inia most roents/ rats, s?uirrel, rabbits, birds and bats have been found to be free of ra#ies. ;owever, following e9posure to mongoose, (5( is
recommended. Rat #ite cases do not re?uire rabies vaccination but this is a right opportunity
to start pre*e9posure vaccination. Transmission Modes of exposures! ;uman e9posures to rabies can generally be categori=ed
as bite, open wound, mucous membrane, or other types of e9posure! Bite exposure: Any penetration of the skin of a person by the teeth of a rabid
or potentially rabid animal. Open wound exposure: 0ntroduction of saliva or other potentially infectious
material /cerebrospinal fluid, spinal cord, or brain tissue1 from a rabid or potentially rabid animal into an open wound /e.g., broken skin that bled within the past #4 hours1. Mucous membrane exposure: 0ntroduction of saliva or other potentially
infectious material /cerebrospinal fluid, spinal cord, or brain tissue1 from a rabid or potentially rabid animal onto any mucous membrane /eyes, nose, mouth1.
5
Understanding Rabies Rabies
Other exposure ! Any interaction with a rabid or potentially rabid animal where
a bite, open wound, or mucous membrane e9posure cannot be definitively ruled out. Air#orne infections, such as inhaling an aerosol of infected animal brain tissue
in virus laboratories, or of contaminated air in bat*inhabited caves, have been reported. )ats that are the easiest to approach and capture /unable to fly, etc.1 are the most likely to have rabies. Bat Ra#ies is not present in Inia. Iatro&enic ra#ies cases have occurred in patients who received cornea, kidney,
liver, or blood vessel graft transplantation from donors who had undiagnosed rabies. Transmission of ra#ies #y #"oo transfusion
There has never been a reported case of rabies infection via a blood transfusion. iremia has not been demonstrated, and the virus is intraneuronal during the incubation period. There is no evience to suggest that an apparently healthy blood donor can transmit rabies, even if incubating clinical rabies. 7abies cannot be transmitted to doctors+assistants conducting postmortem of a person who died of rabies. As per :entre for Disease :ontrol and (revention /:D:1 "orbidity and "ortality @eekly 7eport /""@71, no confirmed case of rabies has ever been reported in persons who performed a postmortem e9amination of people or animals, although contact with decedents with confirmed or suspected rabies can cause an9iety. 5ven from living patients with rabies, human*to*human transmission has been documented only rarely, /in cases of organ or tissue transplantation1. )oth :D: and the @orld ;ealth >rgani=ation /@;>1 have stated that the infection risk to health*care personnel from human rabies patients is no greater than from patients with other viral or bacterial infections. 0n addition, rabies post*e9posure prophyla9is /(5(1 is available for e9posed personnel. Nevertheless, because of the nearly universal fatal outcome from rabies, both :D: and @;> recommend that all personnel working with rabies patients or decedents adhere to recommended precautions. 5ven the minimal risk for rabies virus transmission at autopsy can be reduced by using careful dissection techni?ues and appropriate personal protective e?uipment, including an N2 or higher respirator, full face shield, goggles, gloves, complete body coverage by protective wear, and heavy or chain mail gloves to help prevent cuts or sticks from sharp instruments or bone fragments.
6
Understanding Rabies Rabies
(articipation in the autopsy should be limited to persons directly involved in the procedure and collection of specimens. (revious vaccination against rabies is not re?uired for persons performing such autopsies. (5( of autopsy personnel is recommended only if contamination of a wound or mucous membrane with patient saliva or other potentially infectious material /e.g., neural tissue1 occurs during the procedure. Pat'o&enesis T'e first event in rabies is the inocu"ation of virus through the s$in, usually
through a bite that delivers virus*laden saliva. 0nitial viral replication appears to occur within striated muscle cells at the site of inoculation. 7eplication may occur in muscle+subcutaneous +nerve tissues. The virus gets attached to nicotinic acetylcholine receptors at the neuromuscular Bunction and enters the peripheral nerves.The virus then spreads centripetally up the nerve to the !NS, probably via peripheral nerve a9oplasm, at a rate of &*%$ mm+hour. >nce the virus reaches the :N, it replicates almost e9clusively within the grey matter and then passes centrifugally along autonomic nerves to other tissues the salivary glands, adrenal medulla, kidneys, lungs, liver, skeletal muscles, skin, and heart. (assage of virus into the salivary glands and viral replication in mucinogenic acinar cells facilitates further transmission via infected saliva. There is no viremia in 7abies. Essentia"s of ra#ies ia&nosis +yrop'o#ia and aerop'o#ia are pathognomonic for rabies and occur in $I
of patients. Attempting to drink or having air blown in the face produces severe laryngeal or diaphragmatic spasms and a sensation of asphy9ia. This may be related to a violent response of the airway irritant mechanisms. 5ven the suggestion of drinking may induce hydrophobic spasm. ;ydrophobia is typically uni?ue to human beings. Types of ra#ies
There are mainly t%o types of rabies! %. Furious 1encep'a"itic2 type, t wo*third of rabies patients suffer from typical furious type of rabies. The virus replicates in portions of the brain including the hippocampus, amygdala, anterior thalamic nuclei and limbic corte9. urious rabies has t'ree carina" si&ns?
7
Understanding Rabies Rabies
• • •
luctuating consciousness, episodes of e9citement and hallucinations. (hobic spasms Aerophobia, ;ydrophobia and (hotophobia. Autonomic dysfunctions like increased salivation, e9cessive sweating, priapism F pupillary abnormalities.
0t is typically believed that salivation and vomiting are linked, and contribute to the apparent hydrophobia /fear of water1 in patients. These symptoms can last for few days, after which the patient may suffer from the second type of rabies, or may slip into a coma and die. 0t is when suffering from furious rabies that a person or animal is likely to attack those near them, and spread the disease. #. Dumb 1para"ytic2 type which is characteri=ed by flaccid muscle weakness, constipation, urinary retention, stupor and coma. +yrop'o#ia is usually absent in these cases. This is a condition resembling Guillain )arre yndrome. Dumb 7abies occurs as the result of the virus replicating in the brainHs neocorte9. 0t is much harder for a doctor to diagnose rabies in its CdumbE form than it is in its CfuriousE form, because the symptoms are less indicative of a specific medical issue. )oth forms are progressive and will lead to death, usually within - days in patients with encephalitic rabies and & weeks in those with paralytic rabies. !"inica" features of ra#ies in 'umans
The incu#ation perio of rabies that is the time interval between the e9posure to virus and the onset of symptoms, is usually from $& weeks to $& months /rarely $4 days to $# years1. 0n rabies, a long and variable incubation period is well known. The recore "on&est incu#ation perios have been %2 years and #- years. The later was recently reported from (hilippines. During most of the long incubation period of rabies, the virus likely remains close to the site of viral entry. :entripetal spread to the central nervous system and spread within the central nervous system occur by fast a9onal transport. The incubation period varies with the amount of virus transmitted, virus strain, site of inoculation /bites closer to the head have a shorter incubation period1, host immunity and nature of the wound. !'i"ren are at an increased risk of a shorter incubation period because of
their short stature and bites are often closer to :N. "ultiple bites to the head and neck are associated with very short incubation periods less than % month. 8
Understanding Rabies Rabies
(eople who are immuno*compromised will most likely be more susceptible to rabies. 7abies is usually undetectable during the incubation period, and infections can also be difficult to diagnose when the clinical signs first appear. Proroma" synrome /
•
•
•
• •
(ain or paraesthesiae at the site of the bite is well known as a diagnostically useful prodromal symptom occurring in one*third to two*thirds of cases. 0n Thailand, however, a specific type of paraesthesiae*itching*was the earliest symptom in W4$I of cases. 0tching occurred at the site of the healed bite wound or involved the whole bitten limb and was sometimes so intense as to provoke fren=ied scratching and e9coriation of the skin. The e9planation for local paraesthesiae may be the multiplication of virus in the dorsal root ganglion of the sensory nerve supplying the area of the bite. (ain behind the grafted eye was an early symptom in three of the four patients who developed rabies following corneal transplants. (riapism with fre?uent spontaneous orgasms was the first symptom in one Thai patient. ever, malaise, nausea and vomiting. The skin becomes sensitive to changes of temperature, especially air currents.
Neuro"o&ic sta&e /
Aphasia 0n coordination (aresis (aralysis "ental status changes ;yperactivity
@ate symptoms • • • •
;ypotension :ardiac arrhythmias Disseminated intravascular coagulation /D0:1 :ardiac arrest
9
Understanding Rabies Rabies
!oma /"ay last for $*%4 days1 Deat' usua""y occurs %it'in a fe% ays after appearance of c"inica" symptoms. Detection of ra#ies virus 1a2Dia&nosis of ra#ies in anima"s In anima"s, rabies is diagnosed using the irect f"uorescent anti#oy 1FA2 test, which looks for the presence of rabies virus antigens in brain tissue.
A diagnosis of rabies can be made after detection of rabies virus from any part of the affected brain, but in order to rule out rabies, the test must include tissue from at least two locations in the brain, preferably the brain stem and cerebellum. 1#2Dia&nosis of ra#ies in 'umans Severa" tests are necessary to diagnose rabies ante*mortem /before death1 in
humansV no single test is sufficient. Tests are performed on samples of saliva, serum, spinal fluid, and skin biopsies of hair follicles at the nape of the neck. Sa"iva can be tested by virus isolation or reverse transcription followed by polymerase chain reaction /7T*(:71. Serum an spina" f"ui are tested for antibodies to rabies virus. S$in #iopsy specimens are e9amined for rabies antigen in the cutaneous nerves at the base of hair follicles. Ante 8ortem testin&
All samples should be considered as potentially infectious. Test tubes and other sample containers must be securely sealed /tape around the cap will insure that the containers do not open during transit1. All four samples listed below are re?uired to provide an ante mortem rule out of rabies. 6. Sa"iva
Msing a sterile eyedropper pipette, collect saliva and place it in a small sterile container which can be sealed securely. No preservatives or additional material should be added.
10
Understanding Rabies Rabies
3. Nec$ #iopsy
A section of skin to 8 mm in diameter should be taken from the posterior region of the neck at the hairline. The biopsy specimen should contain a minimum of %$ hair follicles and be of sufficient depth to include the cutaneous nerves at the base of the follicle. (lace the specimen on a piece of sterile gau=e moistened with sterile water and place in a sealed container. Do not add preservatives or additional fluids.
At least $. ml each of serum and : should be collectedV no preservatives should be added. Do not send whole blood. 0f no vaccine or rabies immune serum has been given, t'e presence of anti#oy to ra#ies virus in t'e serum is ia&nostic and tests of : are unnecessary. Anti#oy to ra#ies virus in t'e !SF/ re&ar"ess of t'e immuni=ation 'istory/ su&&ests a ra#ies virus infection.
The rarity of rabies and the lack of an effective treatment make the collection of a brain biopsy for ante mortem testing unwarrantedV however, biopsy samples negative for herpes encephalitis should be tested for evidence of rabies infection. The biopsy is placed in a sterile sealed containerV do not add preservatives or additional fluids.
0n certain cases, human samples may need to be tested for rabies postmortem. resh tissue samples from the central nervous system /brain1 should be submitted. (ostmortem diagnosis of rabies is mae #y immunof"uorescent stainin& of viral antigen in touch impressions of brain tissue. (ortions of the medulla /brain stem1, the cerebellum, and the hippocampus should be fro=en and sent on dry ice to a laboratory. (reservation of tissues by fi9ation in formalin is not recommended if rabies diagnosis is desired.
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Understanding Rabies Rabies
A#out various avai"a#"e tests 6. Direct f"uorescent anti#oy test
The dA test is based on the observation that animals infected by rabies virus have rabies virus proteins /antigen1 present in their tissues. )ecause rabies is present in nervous tissue /and not blood like many other viruses1, the ideal tissue to test for rabies antigen is brain. The most important part of a dA test is fluorescently*labeled anti*rabies antibody. @hen labeled antibody is incubated with rabies*suspect brain tissue, it will bind to rabies antigen. Mnbound antibody can be washed away and areas where antigen is present can be visuali=ed as fluorescent*apple*green areas using a fluorescence microscope. 0f rabies virus is absent there will be no staining. 3. Rapi F"uorescent Focus In'i#ition Test 1RFFIT2
The test measures the ability of antibodies that may be present in a sample to neutrali=e and block rabies virus from infecting the cells used in the test. These antibodies are called rabies virus neutrali=ing antibodies /7NA1. 0mmunofluorescent staining of infected cells is used as an indicator of rabies virus replication. The 70T takes S#$ hours and is both sensitive and specific. @hile rabies virus antibodies can be measured through the application of an 5n=yme*rgani=ation /@;>1. >ther serological tests, such as an 5<0A, are more appropriate for research, and are not recommended for samples re?uiring clinical decision making by clinicians based upon current A:0( and @;> recommendations. 9. +isto"o&ica" e>amination Genera" 'istopat'o"o&y
;istological e9amination of biopsy or autopsy tissues is occasionally useful in diagnosing unsuspected cases of rabies that have not been tested by routine methods. @hen brain tissue from rabies virus*infected animals are stained with a histological stain, such as hemato9ylin and eosin, evidence of encephalomyelitis may be recogni=ed by a trained microscopist. This method is nonspecific and not considered diagnostic for rabies. 12
Understanding Rabies Rabies
)efore current diagnostic methods were available, rabies diagnosis was made using this method and the clinical case history. ;istopathology evidence of rabies encephalomyelitis /inflammation1 in brain tissue and meninges includes the following! %. #. &. 4. .
"ononuclear infiltration (erivascular cuffing of lymphocytes or polymorphonuclear cells
Ne&ri #oies
Negri bodies are round or oval inclusions within the cytoplasm of nerve cells of animals infected with rabies. Negri bodies may vary in si=e from $.# to #- Xm. They are foun most freuent"y in the pyramidal cells of AmmonYs horn, and the (urkinBe cells of the cerebellum. They are also found in the cells of the medulla and various other ganglia. Negri bodies can also be found in the neurons of the salivary glands, tongue, or other organs. taining with "annYs, giemsa, or ellers stains can permit differentiation of rabies inclusions from other intracellular inclusions. @ith these stains, Negri bodies appear magenta in color and have small /$.# Xm to $. Xm1, dark*blue interior basophilic granules. The presence of Negri bodies is variable. ;istological staining for Negri bodies is neither as sensitive nor as specific as other tests. ome e9perimentally* infected cases of rabies display Negri bodies in brain tissueV others do not. ;istological e9amination of tissues from clinically rabid animals show Negri bodies in about $I of the samplesV in contrast, the dA test shows rabies antigen in nearly %$$I of the samples. 0n other cases, non*rabid tissues have shown inclusions indistinguishable from Negri bodies. )ecause of these problems, t'e presence of Ne&ri #oies s'ou" not #e consiere ia&nostic for ra#ies. -. Immuno'istoc'emistry 1I+!2
0;: methods for rabies detection provide sensitive and specific means to detect rabies in formalin*fi9ed tissues. These methods are more sensitive than histological staining methods, such as ;F5 and ellers stains.
13
Understanding Rabies Rabies
4. E"ectron microscopy
The ultra structure of viruses can be e9amined by electron microscopy. Msing this method, the structural components of viruses and their inclusions can be observed in detail. 5. Amp"ification met'os
amples containing small amounts of rabies virus may be difficult to confirm as rabies*positive by routine methods. irus isolation in cell cultures increases the virus concentration because the virus replicates in cell cultures. "ouse neuroblastoma cells /"NA1 and baby hamster kidney /);K1 cells provide an e9cellent environment for amplification of rabies virus without the use of animals. Another method for amplifying the nucleic acid portion of rabies virus uses biochemical methods. @ith this procedure, rabies virus 7NA can be en=ymatically amplified as DNA copies. 7abies 7NA can be copied into a DNA molecule using reverse transcriptase /7T1. The DNA copy of rabies can then be amplified using polymerase chain reaction /(:71. This techni?ue can confirm dA results and can detect rabies virus in saliva and skin biopsy samples. Accuracy of t'e tests
)ecause of high sensitivity and specificity of the direct fluorescent antibody /DA1 test, in comparison to virus isolation methods, the FA test is t'e &o" stanar ia&nostic met'o for ra#ies.
During clinical disease, millions of viral particles may be found intermittently in the saliva. 0n theory, only a single rabies particle or virion is re?uired to result in a productive infection. The mass of a single virion has been estimated to be appro9imately ##% thousand kilodaltons. A small proportion of this amount includes viral 7NA which accounts for less than #I of the mass of a single virion. Any rabies test proposed on living animals would need to be e9tremely sensitive to detect very minute ?uantities of protein or nucleic acid. 0n addition, several repeat tests would be needed over time to ensure that rabies virus e9cretion is not missed since viral shedding in the saliva is inconsistent.
14
Understanding Rabies Rabies
Differentia" ia&nosis of ra#ies • • • • • •
5ncephalitis Guillain*)arre yndrome ;erpes imple9 ;erpes imple9 5ncephalitis (oliomyelitis Tetanus
During differential diagnosis, the most important viruses to rule out are +erpes Simp"e> virus type 6an posure Prop'y"a>is 1PEP2
As there is no specific treatment for clinical rabies, key to survival after e9posure to rabies virus is administration of post*e9posure prophyla9is /(5(1 as soon as possible. Deat' is virtually inevita#"e once clinical signs develop. "edical management is supportive and palliative. 0mproper treatment to animal bite victims may lead to rabies death and litigation under !onsumer Protection Act 1!,PRA2. According to :onsumer (rotection Act, the animal bite should be considered as Cmeica" ur&ency and treated with due care. PEP includes
%. #. &. 4. .
As ra#ies is 67 fata"/ t'ere are no contrainications to post e>posure prop'y"a>is. @oca" treatment of %oun1s2
)y mere washing of wounds and application of antiseptics, the risk of rabies reduces by about $I.
15
Understanding Rabies Rabies
The ma9imum benefit of the wound washing is obtained when fresh wound is cleaned immediately. 0t is important to remove saliva containing rabies virus at the site of bite by physical or chemical means. This can be done by prompt and gentle thorough washing with ordinary soap or detergent and flushing the wound with running tap water for at least % minutes. 0f soap or antiviral agent is not available, the wound should be thoroughly washed with water. @ashing of the wound must be done as long as the wound is rawV irrespective of the time elapsed since the e9posure. :are must be taken not to disturb the scab, if formed. After thorough washing and drying the wound, any one of the available chemical agents should be applied vi= (ovidone iodine /)etadine1, Alcohol, :hloro9ylenol /Dettol1, :hlorhe9idine Gluconate and :etrimide solution /avlon * in appropriate recommended dilution1, etc. Discourage local wound applicants like turmeric, neem, red chili, lime, plant Buices, coffee powder etc. Theoretically, the richly innervated areas like head, neck, face, hands and genitals are the most dangerous sites of bite in man. )ut practically, it is often the wounds on legs, which are ignored+neglected, that cause rabies. Avoi
%. Avoid irect touc'in& of wounds with bare hands. :onsidering the importance of this step, the anti*rabies clinics should have proper wound washing facilities. #. !auteri=in& the wound is not advisable as it leaves a very bad scar and also does not confer any additional advantage over washing the wound with water and soap. 0t amounts to malpractice and the doctor can be sued for compensation under :>(7A. &. Avoi suturin& of the bite wound as a rule since it may risk inoculation of the virus deeply into the wound. ;owever, if the wound has to be sutured, it should be done as late as possible from several hours to & days after infiltration of 70Gs. 0f 70Gs is not available, as a last resort, the wound must be flushed with povidone iodine before suturing. The suture should be loose and not interfere with free bleeding and drainage. ;uman and animal bite wounds are best closed by seconary sutures after one week and after proper cleansing and daily wound care. (rimary surgical intervention must be avoided if possible.
16
Understanding Rabies Rabies
4. @e should never try to eepen the bite wound. Deepening of wound for cleaning depends on area of inBury, e9tent of inBury and the aim should be to preserve as much tissue as possible and to e9cise dead tissue only. . Do not #ana&e the wound as far as possible and if unavoidable, apply non* adherent, absorbent dressings /paraffin gau=e or "elolin1 to absorb the discharge from the wound. Anima" #ites an Infections
% to #$ percent of dog bite wounds become infected. (uncture wounds and hand wounds are more likely to become infected than scratches. "ost infected dog bite wounds yield polymicrobial organisms. Pasteurella multocida and Staphylococcus aureus are the most common aerobic organisms Systemic anti#iotic treatment for anima" #ites
Msing antibiotics may be helpful, particularly in high*risk wounds. Antimicro#ia"s effective in t'e empiric treatment of patients %it' anima" #ite an 'uman #ite %ouns Anima" #ite
+uman #ite
Amo9icillin*clavulanate /(>1
Z
Z
Ampicillin*sulbactam /01
Z
Z
"o9iflo9acin /(>, 01
Z
Z
Gatiflo9acin /(>, 01
Z
Z
Do9ycycline /(>, 01
Z
Z
8eica" !onitions Associate %it' a +i&' Ris$ of Infection After a Do& Bite
%. #. &. 4. . 8. -. 3. 2.
:hronic disease :hronic edema of the e9tremity Diabetes mellitus 0mmunosuppression
17
Understanding Rabies Rabies
!ate&ori=ation of anima" #ite %oun1s2 *+, classified e9posures into three categories. !ate&ory /Type of contact with a
7ecommended treatment.
suspect or confirmed rabid domestic or wild animal, or animal unavailable for observation1
None, if reliable case history is available Administer vaccine immediately. top treatment if animal remains healthy throughout an observation period of %$ days or if animal is killed humanely and found to be negative for rabies by appropriate laboratory techni?ues.
0. Touching or feeding of animals,
Administer rabies immunoglobulin and vaccine immediately. top treatment if animal remains healthy throughout an observation periodH of %$ days or if animal is killed humanely and found to be negative for rabies by appropriate laboratory techni?ues.
When in doubt of degree of exposure to rabies risk it is safer to over treat than under treat . Bitin& anima"
0t is very important to elicit information about biting animal. !ow risk category includes healthy pets and regularly vaccinated dogs+cats. Moderate risk category includes healthy pets but vaccination status doubtful
or not done. "igh risk category includes rabid, sick, died, stray dogs+cats, or wild animals. ,#servation of #itin& anima" !arrier state of rabies in dogs+cats is not yet conclusively proven and established. ;ence, #ot' *+, an Govt. of Inia recommend observation of
18
Understanding Rabies Rabies
animal for 6 ays during post*e9posure treatment. In Europe which is almost rabies free, observation period is 64 ays. The treatment should be started immediately after the bite. The treatment may be modified if animal involved 1o& or cat2 remains healthy throughout the observation period of %$ days by converting post*e9posure prophyla9is to pre*e9posure vaccination by skipping the vaccine dose on day %4 and administering it on day #3 while using 5ssen chedule. The observation period is va"i for o&s an cats on"y. The natural history of rabies in mammals other than dogs or cats is not fully understood and therefore the %$*day observation period may not be applicable. The rationale for observation is that if the animal is incubating rabies, they will show signs of disease in the ne9t &* days and die subse?uently in another &* days. @hether a dog bite was provoked rather than unprovoked should not be considered a guarantee that the animal is not rabid as it can be difficult to understand what an attacking dog considers provocation for an attack. Anti Ra#ies
All human cases of rabies were fatal until a vaccine was developed in %33 by
•
Qoseph "eister, a 2 year old boy was severely bitten by a rabid dog. >n Quly 8th, %33,
+istorica" eve"opment of ra#ies vaccines
%33! (asteur vaccine,
0nactivated virus using formalin and phenol
•
0nfected adult rabbit, sheep, or goat brain tissue
%2! uen=alida vaccine, Drs uen=alida and (alacios •
•
uckling mouse brain /")1 vaccine Decreased reactogenicity with improved immunogenicity %$*% doses re?uired
19
Understanding Rabies Rabies
%28! Duck embryo vaccine, first effective attempt at cell culture vaccine •
Duck embryo vaccine /D51
•
(oorly immunogenic, high rate of allergic reaction. topped in %23$
%2-$s! "odern cell culture vaccines •
;ighly immunogenic with good safety profile
8oern Anti)ra#ies vaccines being used now are Tissue !u"ture
carcinogenic but it loses its carcinogenicity because of its hydrolysis during the process of inactivation of rabies virus. As a &enera" ru"e, live attenuated viral vaccines induce better immunity. )ut, *+, 'as for#ien t'e use of "ive attenuate ra#ies vaccine in 'umans
because live attenuated vaccines always carry risk of reverting to virulent forms. 0f such a vaccine is given to human beings, it may cause fatal disease. Iea" reuirements of a ra#ies vaccine •
•
•
Pure? ;ighly purified and well*tolerated primary cell culture vaccine with
e9cellent safety profile Po%erfu"? ;ighly potent, provides early and long*lasting protective antibiotic titers Protection? ;ighly efficacious and trusted for use in all @;> recommended 0" and 0D regimens.
These are! %. (urified vero cell rabies vaccine /(71 * erorab, \prab, Abhayrab, 0ndirab and erova9*7. #. (urified chick embryo cell vaccine /(:5:1 * 7abipur, a9irab*N &. ;uman diploid cell vaccine /;D:1* 7abiva9 4. (urified duck embryo vaccine /(D51 * a9irab 5ach 0" dose is available in a single dose vial only. 7esponse to rabies vaccination is a uni?ue mi9 of specificities to rabies virus antigens. Antibodies develop out of intrinsic host responses and in response to e9trinsic factors such as the amount of antigen given, type of antigen, and route of e9posure or vaccination. There may be substantial variation in the neutrali=ing activity and ?uantity of rabies virus neutrali=ing antibodies /7NA1
20
Understanding Rabies Rabies
produced. Therefore, the strain of virus used in antirabies vaccine plays a role in eliciting the re?uired response. ompared to other continuous cell lines based rabies !accines, P" !accine with PM strain has se!eral ad!antages, these includes: •
•
This method provides vaccine with high yield, greater potency and immunogenicity which makes the vaccine comparatively cost effective and uni?ue. 0t is more readily scalable to large scale commercial vaccine production.
>f the currently available T:s such as ;D:, (:5:, (7, and (D5, a"" are eua""y &oo and approved by @;>. All are interc'an&ea#"e following non availability of one brand or due to allergy to one of the ::s or (D5. All are considered protective throughout the world against ifferent strains of rabies viruses in different parts of the world. 5ach vaccine has its o%n merit. 6. Purifie
ero cell line is a continuous cell line initiated in %28# by asumura /Qapan1 from kidneys of an African green monkey. erorab was developed in %234.0t is a free=e*dried product composed of ("+@0 &3 %$&*&" strain. The rabies virus is produced on ero cell lines, inactivated with beta propiolactone and purified so that the potency of one dose of vaccine is superior to #. 0M. 3. Purifie c'ic$ em#ryo ce"" vaccine 1P!E!<2? ira#)N/ Ra#ipur a.
•
• •
• • •
a9irab N is manufactured in Rydus accine (lant which has state*of*the*art manufacturing facility. a9irab N is @orldHs %st (urified :hick 5mbryo :ell :ulture 7abies accine /(:5:1 with Pitman#Moore $PM% &d!antage. (itman "oore train is the most table F afe train for biologicals. a9irab N contains o 0ntact 0nactivated irus o ;igh G F N (rotein a9irab N has double tabili=er. Approved by D:G0 both for (re e9posure and (ost e9posure prophyla9is. Approved both for 0ntramuscular /0.".1 or 0ntradermal /0.D.1 route of Administration.
21
Understanding Rabies Rabies
#. Ra#ipur
7abipur is a purified, potent and efficacious (:5: rabies vaccine. 0n the M, (:5: has received DA approval and is marked under the brand name of 7abAvert. 0t is manufactured from the lury <5( rabies virus strain grown in a culture of chick embryo fibroblast cells, inactivated with beta*propiolactone, stabili=ed with a gelatin product and purified by =onal centrifugation. (:5: vaccine is generally contraindicated in persons allergic to egg proteins. 9. +uman ip"oi ce"" vaccine 1+D!<2 Ra#iva>
;D: is of homologous /human1 origin, considered by many as the CpurestE antigen. 0t is prepared with (itman*"oore strain of rabies virus. ;D: vaccine was developed by propagating the ("*%$&*&" strain of the rabies virus on diploid cells of human origin. 0n %284, @iktor et al used the @0&3
0t is the time ta$en by Anti*7abies vaccine to prouce protective "eve"s of anti#oies in the patient. The window period is of -*%4 days.
@;> recommends that the vaccine potency should be at least #. 0M per dose. The potency is the capacity of the vaccine to induce immune response. accine must be store at Z#$ : to Z 3$ :. !aution •
• •
The modern anti*rabies vaccines should not #e i"ute with tetanus to9oid or any other diluents other than that provided with the vaccine. 0f the vaccine was accidentally kept in free=er, it should not be used. Fu"" course of rabies vaccine must be given even if sero*protective levels are obtained after #*& inBections. This is to cover a longer incubation period of rabies as it can be more than & weeks and also to increase the ce""u"ar
22
Understanding Rabies Rabies
immunity an interferon prouction that also play a role in the mechanism •
of protection. A person receiving+completed antirabies immuni=ation can onate #"oo. ;owever, the recipient does not benefit from the transfer of rabies* neutrali=ing antibodies due to hemodilution.
• •
7abies vaccine can be given to a child with c'ic$en po> or meas"es and it is effective. 0f possible administration of measles vaccine should be postponed by a fortnight after the completion of antirabies immuni=ation. 7abies vaccine can be given to a patient with aunice. everal studies of patients with +I
Bite #y a vaccinate o&
Although unvaccinated animals are more likely to transmit rabies, vaccinated animals can also do so if the vaccination of the biting animal was ineffective for any reason. A history of rabies vaccination in an animal is not always a guarantee that the biting animal is not rabid. Animal vaccine failures may occur because of improper administration or poor ?uality of the vaccine, poor health status of the animal, and the fact that one vaccine dose does not always provide long*lasting protection against infection in dogs. PEP is reuire for a person #itten #y a vaccinate o&. accinating the pet dog is primarily to protect it against contracting rabies following bites by stray rabid dogs+animals. It s'ou" #e note that!
%. No veterinary vaccine offers %$$I protection against rabies. #. 7abies is en=ootic in our stray dog+animal population. &. The facility of measuring protective rabies antibody titer is available only at few centers in 0ndia. 23
Understanding Rabies Rabies
4. . 8. -. 3.
The immuni=ation record of dog may not be always available. )ooster dose may not have been given to dog. 8I of dogs found rabid have a reliable pre*e9posure rabies vaccine history 8#I of dogs found rabid are less than % year old and 4$I of dogsH vaccinated only one time lose most of their immunity 4*8 months later.
o in view of above facts and practical difficulties, rabies being %$$I fatal, we should start rabies (5( vaccination even if a person is #itten #y a vaccinate o&. PEP vaccination sc'eu"e 1*+, ESSEN)I82
The schedule is one inBection on days $, $&, $-, %4 and #3. /Day $ means day of first dose of vaccine and not the day of bite1. accine should be inBected deep into deltoid muscle /in Adults1 or antero* lateral aspect of thigh /in :hildren1. Note t'at •
•
• •
•
• •
First t'ree oses of modern rabies vaccine must be very time"y and for the
fourth and fifth, one or two days of variation is permissible. These vaccines must not be administered in &"utea" region as the gluteal fat may retard vaccine absorption resulting in delayed and lower seroconversion. All modern rabies vaccines have a uniform osa&e for a"" a&e groups. If ue to some reasons only initial three inBections on days $, & and - were given, three inB. may provide protective antibody titers for about+up to & months. In case, day $ and & inB. were given and inB. due on day - was postponed because the dog was kept under observation but the dog dies between 3 and % days, three doses of vaccine must be given as close to the original dates of the schedule and a"" five in. must #e comp"ete #y ay 3. There is no sin&"e ose vaccine or a vaccine that gives lifelong immunity. Any maor sur&ery can be conducted along with antirabies treatment.
Day # dose should be doubled in?
%. (atients who seek treatment after a delay of 43 hours or even months after having been bitten should be dealt in the same manner as if the e9posure occurred recently. #. (atients with very high risk e9posures or e9tensive bites,
24
Understanding Rabies Rabies
&. 0mmunodeficient patients or on immunosuppressive drugs, such as steroids, antimalarials, anticancer drugs. 4. everely malnourished patients, . (atients with underlying chronic disease like liver cirrhosis and in 8. (atients where 70G is indicated but unavailable. 'ouble dose of !accine is not a substitute for ()*.
Reasons for Ra#ies Post)E>posure Prop'y"a>is Fai"ures
%. #. &. 4. . 8. -.
0nappropriate local wound treatment (oor ?uality of rabies vaccine No 70G administered aulty handing + mistakes /improper dilution, spills, etc1 0mproper administration of vaccine Delayed initiation of (5( accination schedule not complete
PEP comp"iance is "o% in Inia • • • •
Mse of rabies vaccination in e9posed humans is low] 4$I Mse of 70G negligible] #.%I ;uman rabies victims did not receive any A7 ] -2I :ompliance to the full course is low ] 4$.I
Intraerma" vaccination 1IDR< Ra#ies2 in Inia
The production of emple accine, which was a sheep brain derived Nerve st Tissue
on %2th "ay, #$$8 in Mttar (radesh followed by few other states. The 0D route has been permitted to be used in se"ecte anti)ra#ies c"inics 1AR!s2 having an ade?uate number of patients /at least +day1 seeking post* e9posure prophyla9is against rabies every day to make 0D7 viable and cost* effective.
25
Understanding Rabies Rabies
8oe of action
0t is deposition of approved modern rabies vaccine /or antigen1 in the layers of dermis of skin by which the immuno*receptive
Msing aseptic techni?ue, reconstitute the vial of free=e*dried vaccine with the diluents supplied by the manufacturer. @ith % ml syringe draw $.# ml /up to #$ units if a %$$ units syringe is used or up to 3 units if a 4$ units syringe is used1 of vaccine needed for one patient /i.e. $.% ml per 0D site \ # sites1 and e9pel the air bubbles carefully from the syringe thereby removing any dead space in the syringe. Msing the techni?ue of ):G inoculation, stretch the surface of the skin and insert the tip of the needle with bevel upwards, almost parallel to the skin surface and slowly inBect half the volume of vaccine in the syringe /i.e. $.%mlV either %$ or 4 units1 into the uppermost dermal layer of skin, over the deltoid area, preferably an inch above the insertion of deltoid muscle. 0f the needle is correctly placed inside the dermis, considerable resistance is felt while inBecting the vaccine. A raised papule should begin to appear immediately, causing a peau J oran&e 1oran&e pee"2 appearance. 0nBect the remaining half the volume of vaccine /i.e. $.%mlV either %$ or 4 units1 on the opposite deltoid area. IDR< vaccines
The following vaccines have been approved by D:G0 for use by intra*dermal route. %. #. &. 4.
(urified :hick 5mbryo :ell*:ulture accine /(:5:1 * 7abipur F a9irab*N. (7 /(urified verocell rabies vaccine1 erorab*vial of $. ml, (7 Abhayrab vial of $. ml., ;uman )iological 0nstitute (7 0ndirab, vial of $. ml+%.$ ml. )harath )iotech, ;yderabad.
26
Understanding Rabies Rabies
As far as possible, the same vaccine should be used throughout a course of 0D7. ;owever, in e9igencies, the permitted vaccines are interchangeable. !aution
%. The 0D inBections must be administered by staff trained in this techni?ue. #. The accine vials must be stored at Z#$ : to Z 3$ : after reconstitution and &. The total content should be used as soon as possible, but at least within 3 hours. 4. The $.% ml. 0D administration of cell*culture vaccine should create a wheal of at least mm diameter with Cpeau e oran&e appearance. . @;> recommends that in cases where the wheal over the skin is not formed then the patient should receive another dose of vaccine at a site nearby. 0f the 0D7 fails in any one of the sites after two attempts, then the vaccine must be given by 0" route and the remaining doses of the schedule given by 0" route only. Note? •
•
• •
There are no dietary restrictions during 0D7. ;owever, alcohol may be avoided as it may affect the immune response. 7outine sera testing for rabies antibodies to know 0D7 efficacy is not re?uired. (regnancy and lactation are not contraindications for 0D7. There is no need to alter the dose or schedule of any concomitant medication during 0D7.
ollowing re)e>posure the bitten person needs only two doses of $.% ml. of 0D dose at one site only, on day $ and day &. 70Gs are not needed. (roper wound treatment is very important. Sie effects
:ell culture vaccines have proved remarkably safe and free of significant adverse events. ;owever, mild symptoms of pain, erythema, irritation or swelling at the intradermal inBection sites occur in &I to 2#I of patients. The most fre?uent symptom is local irritation in -I to 84I of vaccines. Generali=ed symptoms reported by &I to %4I of recipients include headache, fever and influen=a* like illness. Transient macula papular and urticarial rashes are occasionally seen. All these adverse effects are mild, transient and self limiting and rarely call for the use of anti*histamines /tablet or syrup Avil1 and analgesics.
27
Understanding Rabies Rabies
Dose an sc'eu"e of IDR<
The 0" dose of erorab /(71 and Abhayrab /(71 is $.mposure vaccination, $.% ml of 0D*approved vaccine is to be given 0D over one deltoid on days $, - and #% or #3 days. Ei&'t)site intraerma" re&imen 1C-66 re&imen2
>ne dose of $.% ml is administered intradermally at eight different sites /5ither upper arms, lateral thighs, supra*scapular region, and lower ?uadrant of abdomen1 on day $. >n day -, four $.% ml inBections are administered intradermally into each upper arm /deltoid region1 and each lateral thigh. ollowing these inBections, one additional $.% ml dose is administered on days #3 and 2$. This regimen lowers the cost of vaccine administered by intramuscular regimens and generally produces a higher antibody response than the other recommended schedules by day %4. 0t does not result in a significantly earlier antibody response and in order to ensure optimal treatment, a passive immune product must be administered to patients presenting with severe e9posures. +o%ever/ t'is re&imen is not approve for use in Inia #y D!GI. 0t is recommended by many internationally reputed e9perts that the phenomenon of mi>in& of I8 an ID sc'eu"es is not to be practiced and must #e avoie as far as possible. Sites for IDR<
0D7 can be given in deltoid region, supra*scapular, anterior abdominal wall and the upper part of thigh. !ontrainications to IDR<
%. (atient on chloro?uine. #. (atient on long term steroid usage. &. 0mmunocompromised patient or on any immunosuppressant therapy. 0n such cases, the rabies vaccine should be given 0".
28
Understanding Rabies Rabies
Potency of IDR<
>nly three countries are practicing 0D7 in regular patients attending regular anti*rabies clinics /A7:s1 for more than ten years. These countries are Thailand, (hilippines and ri
Few suggestions by $%&R' for more effecti!e implementation of )'(
a. The accurate dosage of vaccine can be done if separate insulin syringes are used for each site of administration. b. or children below years of age, it is advisable to adopt 0" vaccination. !riterion for protection 1Seroconversion2 an its importance
The effectiveness of modern tissue rabies vaccines is measured by their ability to protect persons e9posed to rabies and to induce antibodies to rabies virus. The definition of a minimally acceptable antibody titer varies between laboratories and is influenced by the type of test conducted. The @;> specifies a rabies virus neutrali=ing antibody /7NA1 titer of $. 0M+ml as ade?uate for protection. The faci"ity for t'is test is available at N:D: Delhi, :70 Kasauli, (asteur institute :oonnor, N0 (une and N0";AN )angalore. Sero"o&ica" assays to measure ra#ies neutra"i=in& anti#oies
T%o recogni=ed tests by @;>! RFFIT /rapid fluorescent foci inhibition test1, &o" stanarJ. 70T test is t'e on"y internationa""y approve procedure for measuring rabies •
•
neutrali=ing antibodies. FA
5<0A is not an appropriate test system, as it does not measure neutrali=ing antibodies.
29
Understanding Rabies Rabies
(oints that should be considered as to whether a person should receive a #ooster ose of rabies vaccine when their antibody level falls below $. 0M+m< are! •
• •
•
•
Anticipated risk of e9posure /i.e., routinely handling sick animals or rabies reservoir species in en=ootic areas1
Ra#ies Immuno&"o#u"in 1RIG2 RIG is a "ife savin& drug in all category & e9posures and in a few category # e9posures. Use of RIG is as "o% as 3.67 in our country. Failure to advice R'(s attracts litigation)compensation under &onsumer %rotection $ct for deficient)faulty medical service. Fo""o%in& situations nee RIG? • •
•
All :ategory 000 e9posures. 5ven :ategory 00 e9posures in immuno*compromised+ immunosuppressed individuals. )ites by all wild animals vi=. by mongoose, Backal, fo9 etc.
Importance of RIG
The rationale behind the use of 70G is above allV to rapidly neutrali=e the virus locally inside of the wound/s1 before it enters the peripheral nerve endings. 70Gs are specific rabies*virus*neutrali=ing antibodies /or their immune*active fragments1 that immediately bind to the rabies virus on contact. >nce the viruses are coated with antibodies, they cannot adsorb onto and enter the nerve endings. This results in a further reduction /and in some cases complete obliteration1 of the inoculated virus, even in deeper tissues where washing and cleansing may not have reached. 70G provides local protection during the time gap until the appearance of vaccine*induced anti*bodies in protective concentration - to %$ days later, thereby protecting the patient during the critical first week after infection. RIGs are never to be used a"one to treat animal bite victims.
30
Understanding Rabies Rabies
70G should not #e &iven after ay 0 if a modern rabies vaccination has already been started without 70G. Types of RIGs
There are two types of 70Gs! %. +uman RIG /;70G1! Available with a potency of %$ 0M+ml. #. Euine RIG /570G1! Available with a potency of &$$ 0M+ml. Dosa&e of RIGs 'osage for administration is decided on the basis of body weight.
or ;70Gs! Dosage is #$ 0M per kg body weight subBect to a ma9imum of %$$ 0M. ;70G has a longer half*life /about #% days1. or 570Gs! Dosage is 4$ 0M per kg body weight subBect to a ma9imum of &$$$ 0M. Avai"a#i"ity of ifferent RIGs in Inia +RIG Brans
%. )erirab*(* manufactured by :< )ehring Gmb;, Germany and marketed by )harat erum F accines
%. Anti 7abies erum * manufactured by :70 Kasauli. #. 5?uirab * manufactured and marketed by )harat erum F accines
70G is more effective if infiltrated immediately or within #4 hours of animal bite along with first dose of vaccine. 0f vaccine alone was started, then 70G can be given up to - days after starting first dose of vaccine. )deally , rabies vaccine should precede 70G. ;owever, in e9ceptional situations, appro9imately within % hour after administering 70G, the vaccine must be given.
31
Understanding Rabies Rabies
Precautions to #e ta$en %'i"e aministerin& RIGs
%. (atient should not be on an empty stomach. #. 70Gs vial taken out from the refrigerator should be kept outside for a few minutes to warm it to room+body temperature. &. @hile infiltrating 70Gs into the bite wound, care must be taken to avoid inBecting into blood vessels and nerves. 4. @hile inBecting into finger tips, care must be taken to avoid compartment syndrome. . All emergency drugs and facilities for managing any adverse reactions must be available. 8. or 570G, keep the patient under observation for at least one hour after 570G administration and then send home. S$in sensitivity testin& L interpretation
"aBority of reactions to 570G result from complement activation and are not I&E meiate and will not be predicted by skin testing. The recent *+, recommenation states that there are no scientific grounds for performing a skin test prior to the administration of 570G, because testing does not predict reactions and 570G should be given whatever the result of the test. ;owever skin test is manatory to avoid any possible litigation under consumer protection Act /:>(7A1 in 0ndia. 0nBect $.% ml 570G diluted %!%$ in physiological saline intra*dermally into the fle9or surface of the forearm to raise a bleb of about &*4 mm diameter. 0nBect an e?ual amount of normal saline as a negative control on the fle9or surface of the other forearm. After % minutes an increase in diameter to W %$ mm of indurations surrounded by flare is taken as positive skin test, provided the reaction on the saline test was negative. An increase or abrupt fall in blood pressure, syncope, hurried breathing, palpitations and any other systemic manifestations should be taken as positive test. A negative skin test must never reassure the physician that no anaphylactic reaction will occur. Those administering 570G should always be ready to treat early anaphylactic reactions with adrenalin. The dose is $. ml of $.% percent solution /% in %$$$, %mg+ml1 for adults and $.$% ml+kg body weight for children, inBected subcutaneously or 0".
32
Understanding Rabies Rabies
"ost 570Gs that are manufactured presently are highly purified and the occurrence of adverse events has been significantly reduced. Mnlike the original unpurified rabies antisera which resulted in adverse reactions in as many as 4$I of recipients, the adverse*reaction rate of patients receiving highly purified 570Gs has been reduced to J%#I. ;owever adverse event like anaphyla9is cannot be completely ruled out. Averse reactions to +RIGs
0n rare cases the following adverse reactions may occur! •
•
•
Allergic reactions including fall in blood pressure, dyspnoea, cutaneous reactions, in isolated cases reaching as far as anaphylactic shock, even when the patient has shown no hypersensitivity to previous administration of 0mmunoglobulins. Generali=ed reactions such as chills, fever, headache, malaise, nausea, vomiting, arthralgia and moderate back pain :ardiovascular reactions particularly if ;70G is inadvertently inBected intravascularly.
•
There may be transient tenderness at the inBection site. )rief rise in body temperature. kin reactions are e9tremely rare. 70G must never be given intravenously since this could produce symptoms of shock, especially in patients with antibody deficiency syndromes. erum sickness occurs in %I to 8I of patients usually - to %$ days after inBection of 570G, but it has not been reported after treatment with ;70G.
570G should preferably be given in a hospital setting. Averse reactions to ERIGs are mana&e as fo""o%s?
Anti*sera of e?uine origin may cause anaphylactic shock.
33
Understanding Rabies Rabies
Management if anaphylactic reaction occurs:
%. Adrenaline! The dose is $. ml of $.% percent solution /% in %$$$, %mg+ml1 for adults and $.$%ml+kg body weight for children, inBected intramuscularly /0"1. #. 0nB ;ydrocortisone! %$$ mg stat and 8 hourly 0+. &. 0nB :hlorphinaramine 0+. 4. 0nB 7anitidine 0+. If patient is sensitive to 570G, ;70G should be used. (atient who had prior
e9posure of anti*sera /e.g.*Anti*tetanus serum, anti*diphtheria serum1 should receive subcutaneous dose of 0nB adrenaline /the re?uirement will be half dose of that re?uired for treatment for anaphyla9is1. 8oe of aministration of fu"" ose of RIGs
0t is important to infiltrate all wounds with 70Gs. 0ntra*muscular /0"1 administration of 70Gs is of very little value. As much of the calculated dose of 70G, as is anatomically feasible, should be infiltrated into F around all the wounds. 0n the event that some volume of 70Gs is left over after all wounds have been infiltrated, it should be administered by deep 0" at a site distant from the vaccine inBection site. 0f the calculated dose of 70G is insufficient /by volume1 to infiltrate all wounds, sterile saline can be used /up to e?ual volume1 to dilute it to permit thorough infiltration. 0f a wound has healed or healing /scab is formed1 the total dose of 70Gs should be given 0" gluteal only. *ote+ 70G should never be administered in the same syringe or at the same
anatomical site as vaccine administration. RIGs in re)e>posure cases Managing re#exposure following post#exposure treatment with T ! 0f re*
e9posed, persons who have previously received full post*e9posure prophyla9is /5ither by 0" or 0D route1 with a potent cell*culture vaccine should now be given only two booster doses, intramuscularly /$.ml+%ml1+intra*dermally /$.% ml at % site1 on days $ and &. (roper wound toilet should be done. Treatment with 70G is not necessary. Managing exposure following pre#exposure prophylaxis with T ! 0f after
recommended pre*e9posure prophyla9is, a vaccinated person is e9posed to
34
Understanding Rabies Rabies
rabies, a proper wound toileting should be done and two 0"+0D /$.% ml at % site1 doses of :ell :ulture accine are given on days $ and &. Treatment with 70G is not necessary. Managing re#exposure following post#exposure treatment with +T ! (ersons
who have previously received full post*e9posure treatment with NT should be treated as fresh case and may be given treatment as per merits of the case. Approac' to a patient reuirin& RIGs/ %'en none is avai"a#"e
0n circumstances where no immunoglobulin are available greater emphasis should be given to proper wound toileting followed by 5ssen chedule of :ell :ulture accine with double dose on day $ at # different sites intramuscularly /$ day # doses on left and right deltoid, &, -, %4 and #3 days1. 0t is emphasi=ed that doubling the first dose of :: is not a replacement to 70G. A full course of vaccine should follow thorough wound cleansing and passive immuni=ation. Important consierations •
•
•
•
•
70Gs can be infiltrated even to already suture %ouns without disturbing the sutures. 70Gs can be safely inBected into already infecte animal bite wounds following proper wound cleansing and administration of appropriate antibiotics. Un#oi"e mi"$ of a rabid animal may contain rabies virus. There is a theoretical risk of humans contracting rabies after having consumed unboiled milk of a rabid animal. 0f a person has consumed milk of a rabid animal, counseling should be done. 0f counseling is not effective, then (r5( by 0" or 0D route or as a last resort a course of (5( /only vaccine1 should be given. 0f the milk is boiled or heated then only counseling or at the most a course of (r5( should be given only due to compulsions in medical practice in 0ndian setting. Kissin& a rabies patient may transmit disease because there may be contact with rabies patientHs saliva. ull post*e9posure immuni=ation must be given either by 0ntramuscular /0"1 or 0ntradermal /0D1 route. 0f there are ulcers in the mouth of the e9posed person, then 70Gs must be given by 0" route. 7abies virus is present in the semen and to some e9tent in va&ina" secretions. (riapism, increased se9ual libido and indulgence are seen both in male and female rabies cases. ;ence, in the e9posed person, a full course of rabies post*e9posure vaccination either by 0ntramuscular /0"1 or 0ntradermal /0D1 route should be given. 0f there is any doubt of category 000
35
Understanding Rabies Rabies
•
•
• •
•
•
•
•
e9posures, that is, abrasion on penis or in vagina, then even 70G must also be given by 0" route. 0f a person has handled or eaten the ra% meat of a rabid animal, he should receive full course of rabies vaccine. 0f the person has eaten raw meat of a rabid animal and has oral ulcers+lesions, he may be given 70Gs in thigh 0" on day $ along with first dose of vaccine. 0f the rabid animal^s saliva falls into the eyes, the eyes should be washed with water+saline and then 70Gs can be instilled as eye drops, after dilution /%!%1 with sterile normal saline along with full course of anti*rabies vaccination. Antibodies from vaccination do not cross an intact #"oo)#rain #arrier. A person does not ac?uire immunity a&ainst natura" ra#ies infection, as it occurs in other viral infections because there is no viremia in rabies and the virus is not accessible to the normal immune mechanism of the body. The antibody production starts only after travelling efferently from :N via mostly autonomic nerves to different target organs. )ut by that time, the neuronal cells of patient^s brain stem are affected. 0n case the mot'er develops rabies, the foetus is safe because rabies virus does not cross p"acenta" #arrier. till the new born should be given full course of rabies (5( vaccination. 0f a vaccinated pet o& ies of suen une>p"aine eat', then all those who came in contact with the saliva of the animal, directly or through its fomites, should be given full (5( vaccination. 0t is advisable to use 'uman vaccines for 'uman and use the veterinary vaccines for animals. If unvaccinate or partially vaccinated pet o& is #itten by a suspected rabid stray dog, then the pet dog should ideally be put to sleep /5uthanasia1. >therwise, full (5( vaccination of pet dog with cell culture vaccine and simultaneous observation of dog for # to 8 months is recommended. (re*e9posure vaccination of all household members is necessary.
Pre)e>posure vaccination 1PrE<2
(re*e9posure /(rebite1 vaccination means immuni=ation before the bite. It s'ou" #e &iven to? • • •
eterinarians and staff 7abies laboratory personnel (ersonnel working in rabies vaccine manufacturing plants
36
Understanding Rabies Rabies
• • • •
@ildlife rehabilitees and animal control workers "ilitary personnel and armed forces Adventure travelers to canine rabies endemic countries :hildren in canine rabies endemic high risk areas
Pre)e>posure vaccination sc'eu"e
The regimen is three 0" inBections on days $, - F #3. (re*e9posure vaccination simp"ifies post*e9posure vaccination because after bite, those who have received full (re*e9posure vaccination, only t%o doses of vaccine at days $ F & are re?uired. RIGs are not reuire /@;> #$$-1. Although no teratogenicity is reported with modern rabies vaccines, pre* e9posure vaccination should be avoie in pre&nant woman. Ra#ies in anima"s
The symptoms of ra#ies in dogs+cats are! Be'aviour c'an&e riendly dog becomes aggressive and vice versa,
As recently as #$$4, a new symptom of rabies has been observed in fo9es. (robably at the beginning of the prodromal stage, fo9es, which are e9tremely cautious by nature, seem to lose this instinct. o9es will come into settlements, approach people, and generally behave as if tame. There are fe% variations in signs of rabies between different species of animals. !att"e with furious rabies attack and pursue man and other animals. A common clinical sign is a characteristic a#norma" #e""o%in&. +ea #uttin& is a characteristic sign in case of rabies in s'eep and &oats. The si&ns of Ra#ies in dogs+cats are! 8otor Para"ysis is most consistent sign in all animals. (aralysis develops and is usually an ascending. First si&ns are weakness or uncoordinated hind limbs. As
paralysis becomes more e9tensive, locomotors dysfunction becomes more pronounced.
37
Understanding Rabies Rabies
Development of parap"e&ia without a history of compatible trauma inBury is highly suspicious of rabies. Animals o not e9hibit +yrop'o#ia. !ontro" of ra#ies in o&s
The classic methods are • •
accination of dogs and :ontrol of dog population
Anima" vaccination remains t'e met'o of c'oice to contro" an eraicate ra#ies. Primary vaccination schedule for the dogs and cats, consists of initial two
doses of vaccine, that is, one dose given at & months of age and the second given % month later. This is followed by a #ooster dose of vaccine every year. Post E>posure Prop'y"a>is /(5(1 vaccination is not very successful in dogs.
The cost of a post*bite treatment in humans is about twenty to one hundred times more costly than the vaccination of a dog. Anima" #irt' contro"? Mnder optimal conditions a given population of dogs
would nearly triple every year. 0n the policy of animal birth control, also referred to as the A): (rogramme, stray dogs are impounded, surgically sterili=ed and released back into the area from where they were picked up. The success of this program hinges on the sterili=ation of -$I of the strays in a given geographic area within si9 months, before the ne9t reproductive cycle beginsV otherwise the entire effort is negated. This target is difficult to achieve, given the large number of strays and the limited resources. ;ence the success of the animal birth control program in controlling the stray dog population is a subBect of dispute and doubt. 8yt's a#out Ra#ies in Inia
ollowing myths about rabies are very much prevalent in 0ndia!* •
• •
(eople apply turmeric, herbal e9tracts and sometimes ghee over the wound area. :hilies, hydrogen* pero9ide and cow dung are some other wrong practices followed mainly in the rural parts of 0ndia. 0n rural areas, people also resort to witchcraft and religious practices. @ashing of wound/s1 can cause hydrophobia.
38
Understanding Rabies Rabies
•
• • • •
Dietary changes can cure, that is, shift from vegetarianism to non* vegetarianism or vice versaV stopping consumption of white things etc. A single dose vaccine will prevent rabies. accines are more effective if taken on empty stomach. >ne should not take bathV eat meat and eggs during vaccination. Gems and stones have magical properties against rabies.
Seasona" variation in o& #ite cases
"a9imum dog bites were observed in the autumn months. 0t is observed that there is an increase during warm*weather months /"ay through August1 and a corresponding decrease during colder months /November through "arch1. +o% can ra#ies #e preventeM •
• • • •
•
;ave your pets vaccinate against rabies. Any pets which come in contact with wild animals are at risk. 0f your cat or dog has been bitten by a wild animal or has bites or scratches of unknown origin, consult the veterinarian immediately. 0f your cat or o& is sic$, seek the advice of your veterinarian. (rotect your pets from stray or wild animals. 7eport stray animals to your local health department. Do not fee or handle %i" anima"s especially those that appear aggressive or sick. Never keep a wild animal as a pet.
8et'os of Eut'anasia /for animals1 6. Intravenous anest'etic Pets are almost always euthani=ed by intravenous inBection, typically a very
high dose of a barbiturate such as pentobarbital. Mnconsciousness, respiratory then cardiac arrest follows rapidly, usually within &$ seconds. #. Stray animals are sometimes put to sleep by animal shelters that put unclaimed and unadopted dogs and cats in a sealed chamber and pump the air out. The animal dies of ano>ia. 9. In'a"ant anest'etic
Gas anesthetics such as isoflurane and sevoflurane can be used for euthanasia in very small animals. The animals are placed in sealed chambers where high levels of anesthetic gas are introduced.
39
Understanding Rabies Rabies
-. !ervica" is"ocation
:ervical dislocation, or snapping of the neck, is a simple and common method of killing small animals such as rabbits. 4. Intraperitonea" inection
@hen intravenous inBection is not possible, euthanasia drugs such as pentobarbital can be inBected directly into a body cavity. 0ntraperitoneal inBection is fully acceptable /although it may take up to % minutes in dogs and cats1 5. S'ootin&
This can be an appropriate means of euthanasia for large animals /e.g., horses, cattle1 The usua" met'o of euthanasia for o&s is by 0 inBection of either concentrated "ag. ulphate solution or euthatol which is concentrated pentabarbitine. th *or" Ra#ies Day? 0t is on #3 eptember.
!onc"usion •
•
• •
•
•
•
•
7abies is the only communicable disease of man that is practically %$$I fatal even today but easily preventable. The @;> estimated the annual number of human rabies deaths to be between 4$,$$$ and -$, $$$. "ost human deaths follow a bite from an infected dog. @ound cleansing and immuni=ations, done as soon as possible after suspect contact with an animal and following @;> recommendations, can prevent the onset of rabies in virtually %$$I of e9posures. >nce the signs and symptoms of rabies start to appear, there is no treatment and the disease is almost always fatal. Globally, the most cost*effective strategy for preventing rabies in people is by eliminating rabies in dogs through animal vaccinations. 4$*8I of dog bite victims are children J% years. :hildren often play with animals and are less likely to report bites or scratches. 0n areas known for rabies, professionals with fre?uent e9posure to animals /e.g. veterinarians1, or who spend a lot of time outdoors /e.g. wildlife specialists or researchers1, particularly in rural areas, should be vaccinated preventively.
40
Understanding Rabies Rabies
A##reviations an Acronyms
A):
Animal )irth :ontrol (rogramme
A5
Avian 5mbryo accines
A(:70
Association for (revention and :ontrol of 7abies in 0ndia
A7:s
Anti*7abies :linics
A7
Antirabies erum
A7
Antirabies accine
AT
Antitetanus erum
A@)0
Animal @elfare )oard of 0ndia
)))
)lood*)rain )arrier
)(<
)eta (ropio
::
:ell :ulture accine
:D:
:enters for Disease :ontrol and (revention Mnited tates
:>(7A
:onsumer (rotection Act
:70
:entral 7esearch 0nstitute, Kasauli, ;.(.
D:G0
Drug :ontroller Govt. of 0ndia
DA
Direct luorescent Antibody Testing
5(0
59panded (rogramme of 0mmuni=ation
570G
5?uine 7abies 0mmunoglobulin
AT
luorescent Antibody Test
;D:
;uman Diploid :ell accine
;70G
;uman 7abies 0mmunoglobulin
0D
0ntradermal
0D7
0ntradermal 7abies accination
0"
0ntramuscular
0M
0nternational Mnits
"NT
"ouse Neutrali=ation Test
N:D:
National 0nstitute of :ommunicable Diseases, Delhi 41
