TREMATODES Trematodes “Flukes” Belong to Phylum Platyhelminthes class trematoda Flat, unsegmented First Intermediate Host for all Trematodes is SNAIL No Coelom, so they are flat Filled with mesodermal parenchyma No blood vessels; simple ladder nervous system Incomplete digestive and circulatory system All digenea are parasitic Digenea has suckers used to attach to the host; oral sucker contains the mouth and ventral sucker serves as the passageway for eggs Muscular pharynx – pumps food into blind ending gut Divided into two groups: Hermaphroditic flukes o Self-fertilizing o Infect organs, foodborne Blood flukes/Schistosomes o Dioecious o Infect by direct penetration Rules: ALL EXCEPT FOR SCHISTOSOMES: 1. Are hermaphroditic (Schisto: dioecious) 2. Require 2 or more Intermediate Hosts (Schisto: 1 IH ) 3. have metacercaria as the Infective Stage (S: cercaria) 4. Transmitted through ingestion (S: skin penetration) 5. have leaf-like appearance 6. have operculated eggs ALL EXCEPT FOR Heterophyes heterophyes: 7. Have two suckers (Heterophyes has three suckers: oral, ventral and genital/gonotyl) MORPHOLOGY: Pass through three forms: Eggs, Multiple Larva stages and adult EGGS:
Primary form recovered from human specimen o Operculum – lidlike structure that opens to release larva o Some have spines (like Schistosoma spp.) LARVAE: o Rarely encountered, occur outside human hosts ADULTS: o Thin, non-segmented, leaf-like in shape and thickness o Typically 1 to 5 cm o Two suckers (oral and ventral) o Simple digestive system and a genital tract o Uses its body surface for absorbing and excreting nutrients and waste products o
General Life Cycle for Hermaphrodites/Organ-dwelling flukes: 1. Egg – exits the FH via feces or sputum At Snail (First IH): 2. Miracidium – released by egg when in contact with fresh water 3. Sporocyst – sac-like larval form 4. Rediae – larval stages that form inside sporocyst 5. Cercaria – free-swimming, encysts on 2nd IH Encysting at 2nd IH (crab, plant, snail, ant, etc): 6. Metacercaria – encysted form of Trematodes Ingestion by Final host: 7. Adult *Schistosomule – emerges from cercaria following penetration of Schistosomes in humans *Schistosome eggs are released via urine or stool *Testis: appearance may be branching, simple or lobate. Arrangement may be oblique, in tandem, or parallel. TREMATODES SCIENTIFIC NAME
COMMON NAME
BLOOD FLUKES Oriental Blood Fluke
Schistosoma japonicum Schistosoma Vesical Blood Fluke haematobium Schistosoma mansoni Manson’s Blood Fluke LIVER FLUKES Fasciola hepatica Sheep Liver Fluke/ Common Liver Fluke Fasciola gigantica Giant Liver Fluke Clonorchis sinensis Oriental/Chinese Liver Fluke Opisthorchis viverrini Southeast Asian Liver Fluke Dicrocoelium Lancet Liver Fluke dendriticum INTESTINAL FLUKES Fasciolopsis buski Giant/Large Intestinal Fluke Echinostoma Garrison’s Fluke ilocanum Heterophyes Heterophid Fluke/Von heterophyes Siebold’s Fluke Metagonimus Heterophid Fluke yokogawai Haplorchis taichui --Gastrodiscoides --hominis PULMONARY FLUKES Paragonimus Oriental Lung Fluke westermanii A. LIVER FLUKES 1. Fasciola hepatica Common Name: Sheep Liver Fluke FH: Man, Sheep, other vertebrae IH 1: Snail (Lymnaea species) IH 2: Aquatic Plants Habitat: Biliary passages of the liver Diagnostic Stage: Unembryonated Eggs *Zoonotic – infections may come from animals *Take note of rules for MoT and IS *Found worldwide, particularly in places where sheep and cattle are raised *and where humans consume raw watercress, including Europe, the Middle East, and Asia
*Natural Host for completion: Sheep. Accidental Host – Man (according to book) Morphology: Adult Cephalic cone: Unique to F. hepatica Broad shoulder Intestinal ceca: branching Testis: Highly branching Egg Operculated Ovoidal, large, brownish-yellow in color Hen’s egg appearance No species differentiation: report simply as Fasciola egg; information regarding patient symptoms and travel history is necessary to diagnose the causative species Life Cycle Notes: Immature eggs are oviposited in the biliary ducts and released in stool Embryonated in fresh water Miracidium – penetrates snail IH, develops into sporocyst, redia and cercaria Cercaria encysts in aquatic plants and develop into metacercaria Ingestion of metacercaria-infected aquatic plants introduces infection into humans Metacercaria excyst into duodenum, migrate through intestines, peritoneal cavity and liver parenchyma Biliary ducts – where metacercaria develop into adults (3-4 months) Adults reside in LARGE biliary ducts Pathology: Halzoun o Pharyngeal Fascioliasis o Common in people eating raw liver Hepatic Fascioliasis “Sheep Liver Rot” Eosinophilia, jaundice, liver tenderness, anemia, diarrhea, and digestive discomfort are sometimes seen Inflammation in the biliary epithelium Liver atrophy Concomitant periductal cirrhosis Diagnosis:
Patient preparation: Three days with liverfree diet to avoid FALSE POSITIVE results DFS/Kato-Katz/FECT Duodenal/Bile Aspirate Recovery of adult worms during surgery Entero Test (nylon string inside capsule), gel diffusion Serology Test – Multidot ELISA Polymerase Chain Reaction/PCR **WHO Standard: Three negative Kato-Katz AND three negative FECT to rule out Fascioliasis Treatment: Bithionol, thiabendazole, Praziquantel Triclabendazole – more effective but not available in the US 2. Clonorchis sinensis Common Name: Chinese Liver Fluke FH: Man, Fish-eating mammals IH 1: Snail (Bulimus fuchsiana and Aloncima species) IH 2: Fish (Cyprinidae species) Habitat: Bile ducts and gallbladder Diagnostic Stage: Ova in the stool *Endemic areas are in Asia including Korea, China, Taiwan, and Vietnam *Reservoir hosts include carnivores like dogs and cats Morphology: Adult: Spatulate Testis: Deeply branching, in tandem Large oral sucker Intestine: Simple Egg: Comma-shaped abopercular end/thickening Opercular shoulders – where operculum rests Old-fashioned light bulb/pitcher-like Hard to differentiate with heterophid eggs, so report as HETEROPHID EGG Life Cycle Notes: EMBRYONATED EGGS are discharged in the biliary ducts and in the stool
Infection of humans occurs by ingestion of undercooked, salted, pickled, or smoked freshwater fish metacercariae excyst in the duodenum and ascend the biliary tract through the ampulla of Vater Maturation takes place in liver (1 month maturation) Adults reside in SMALL and MEDIUM sized biliary ducts Pathology: Bile duct obstruction (intensity is proportional to worm load) Liver carcinoma Colangiocarcinoma/Gallbladder carcinoma *Nitrosamine – a compound excreted by the worm related to development of cancer Diagnosis: Stool Exam (DFS/KK/FECT) Duodenal Aspirate Entero Test PCR Liver Biopsy Surgery/Autopsy – where rarely encountered adult worms are seen only Treatment: Praziquantel Albendazole 3. Opistorchis felineus Common Name: Cat Liver Fluke, Siberian Liver Fluke FH: Cat (Man can also be infected) IH 1: Bithynia spp. IH 2: Cyprinidae fish Habitat: Biliary passages, gallbladder Diagnostic Stage: Ova *Opistorchis viverrini is similar to this (CN: Southeast Asian Liver fluke) Morphology: Adult: Lobate Testes , obliquely/diagonally patterned Egg:
No abopercular thickening Life Cycle Notes: Almost the same as C. sinensis Pathology: Opistorchiasis (colangiocarcinoma) Diagnosis: Stool Exam, Entero Test, Duodenal Aspirate Treatment: Praziquantel
4. Dicrocoelium dendriticum (old name: Fasciola lanceolata) Common Name: Lancet Fluke FH: Cattle, Sheep, Other vertebrates (Man is AH) IH 1: Cionella lubrica (release slime balls: mass of cercaria) IH 2: Formica fusca (ant) Habitat: biliary passages//hepatobiliary spaces in the liver Diagnostic Stage: ova *herbivores are reservoir hosts Morphology: Adult: Lancet shaped Testis: found on the anterior 1/3 portion; Lobate in tandem Egg: Yellowish/brownish thick-walled with large operculum, EMBRYONATED Life Cycle Notes: Common in herbivores No redia stage Pathology: Enlargement of the bile duct Portal cirrhosis Periductal fibrosis Diagnosis: Detection of eggs in stool/duodenal fluid Treatment: Praziquantel B. INTESTINAL FLUKES
1. Fasciolopsis buski Common Name: Giant Intestinal Fluke FH: Man IH 1: Snail (Segmentina, Hippeutis, Gyraulus species) IH 2: Water Plants (Eliocharis tuberosa/Water Chestnut, Eichornia species, Trapa species) Habitat: Small Intestine Diagnostic Stage: Ova *Largest Intestinal Fluke of man *limited to areas of the Far East (China, Thailand, Taiwan, and Vietnam), India and Indonesia *Reservoir hosts: Rabbits, pigs, dogs Morphology: Adult: Largest intestinal fluke Intestinal ceca: Unbranched Testis: In tandem branching (2 dendritic testes) Egg: Large, operculated Indistinguishable from eggs of F. hepatica and F. gigantica Life Cycle Notes: Immature eggs are released via stool Metacercaria excyst in duodenum Development into adult is in intestinal wall (approx. 3 months) Adults’ life span = 1 year Almost the same as F. hepatica; the only difference is the habitat of adult Pathology: Gland abscess Intestinal obstruction Patients may also suffer from malabsorption syndrome, similar in giardiasis Diagnosis: Stool Exam Eggs are indistinguishable from F. hepatica Treatment: Praziquantel, tetrachloroethylene
Praziquantel should be taken with liquids during a meal 2. Echinostoma ilocanum Common Name: Garrison’s Fluke FH: Man, aquatic birds, carnivores, rodents IH 1: Snail (Gyraulus convexiusculus, Hippeutis umbicalis) IH 2: Kuhol (Pila luzonica, Pila conica) Habitat: Small Intestine Diagnostic Stage: Ova Morphology: Adult: Equipped with plaque-like scales instead of spines Oral sucker is protected by the spine called circumoral disk (“collar spine”) Testis: Lobate, in tandem Intestinal ceca: unbranched With structures called vitelline glands or vitellaria Egg: Straw-colored (almost colorless) Operculated Structure inside: “Germ Ball or Yolk” Can be differentiated from other eggs in stool exam Life Cycle Notes: Unembryonated eggs are released via feces May have 1 or 2 generations of rediae Metacercaria excyst in duodenum, and adults reside in small intestine Pathology: Heavy Infection General intoxication Diarrhea Catarrhal inflammation due to the penetration of the sharp-spined collar into the intestinal mucosa Diagnosis: Stool Exam Treatment: Praziquantel
3. Heterophyes heterophyes Common Name: Von Siebold’s Fluke/Heterophid Fluke FH: Man, fish-eating animals and birds (reservoir) IH 1: Cerithidia, Pironella species IH 2: Tilapia and other fresh/brackish water fish Habitat: small intestine Diagnostic Stage: Ova in stool *smallest fluke infecting man Morphology: Adult: grayish in color protected by an outer layer of fine spines (scaly in appearance Has third sucker: the gonotyl or genital sucker Paired testes Egg: Operculated Indistinguishable from Metagonimus yokogawai; shell is thicker than Metagonimus yokogawai but is not enough for species differentiation similar to Clonorchis sinensis but without abopercular thickening Less distinct shoulders compared to Clonorchis sinensis and lack the small terminal knob Life Cycle Notes: Adults release embryonated eggs passed through the feces Infection occurs after ingestion of raw/uncooked freshwater/brackish water fish contaminated with metacercaria Pathology: Abdominal pain and chronic mucous diarrhea and eosinophilia The eggs have the ability to escape into the lymphatics or venules via intestinal wall penetration and to migrate to other areas of the body, such as the heart or brain which result into granulomas in these areas
Diagnosis: Stool exam Species differentiation is difficult due to similarities with Clonorchis sinensis and Metagonimus yokogawai Treatment: Praziquantel 4. Metagonimus yokogawai Common Name: Heterophid fluke FH: Humans, fish-eating mammals and birds IH 1: Semisulcospira species IH 2: Fresh/brackish water fish Habitat: Small Intestine Diagnostic Stage: Ova in stool *smallest human fluke (according to CDC) Morphology: Adult: pyriform in shape with tapering at the anterior end and rounding at the posterior end with a tiny layer of scaly spines heavily distributed over the anterior end ventral sucker/genitoacetabulum - to the side of the midline and closely associated with the genital pore Egg: thinner shell than Heterophyes heterophyes; no species differentiation Life Cycle Notes: Adults release embryonated eggs passed in the feces Pathology: diarrhea and colicky abdominal pain Same symptoms with Heterophyes heterophyes Diagnosis: Stool exam Treatment: Praziquantel 5. Gastrodiscoides hominis
(notes only, wala sa book and CDC) - Pear-shaped: globular appearance > Discoid posterior > Conical Anterior - “Massive” acetabulum - Lay immature eggs - Habitat: Small intestine - Life cycle: Not well studied - Pathology: Mucoid diarrhea, gastritis - Egg: similar to heterophids - Treatment: Carbon Tetrachloride (CCl4) - Praziquantel is ineffective 6. Haplorchis taichui (wala ako mahanap info tungkol dito!) From wiki: Haplorchis taichui is a species of intestinal flukes in the genus Haplorchis. It is a human parasite found in the Philippines. Oxyresveratrol, a stilbenoid found in extracts of Artocarpus lakoocha is effective against H. taichui.
C. BLOOD FLUKES *no metacercaria and redia stages 1. Schistosoma japonicum Common Name: Oriental Blood Fluke FH: Man and other vertebrates IH: Snail (Oncomelania hupensis quadrasi) Habitat: Superior mesenteric veins of small intestine Diagnostic Stage: Ova in stool *Take note of rules for MoT (skin penetration) and IS (fork-tailed cercaria) *Host-permissive: can complete cycle in other vertebrates *Reservoir hosts: dogs, cats, carabaos *Most number of reservoir hosts among the Schistosomes *Endemic in the Philippines Morphology: Adult:
MALE: Hollow structure called gynecophoral canal (receives female during copulation) Testis: 6 to 7, behind the ventral sucker FEMALE: slender, with greatest egg production When in copulation: described as Schistosoma in copula (perpetual copulation); most “romantic” parasites No integumentary tuberculation; aspinous (no spines) Largest among Schistosoma species in man Egg: Ovoid/round/pear-shaped with minute lateral knob Life Cycle Notes: Eggs are released via feces Cercaria penetrate human skin and shed their forked tail, becoming schistosomule Females deposit eggs in the small venules of the portal and perivesical systems Pathology: Due to Adult: Katayama Disease - systemic hypersensitivity reaction to the schistosomulae migrating through tissue Snail Fever Oriental Schistosomiasis Due to Larva: Swimmer’s Itch Diagnosis: Stool Exam o WHO recommendation: Kato-Katz in three stool samples for 3 consecutive days Rectal Biopsy, Liver Biopsy Egg-hatching technique ELISA Ritchie Technique – to quantify eggs Serological Test: Detects three antigens: o Circulating Cathodal Antigen (CCA) o Circulating Anodal Antigen (CAA) o Soluble Egg Antigen (SEA) COPT
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Sensitive, cannot differentiate present from previous infections Confirmatory and definitive test for Schistosomes in the Philippines “Circumoral Precipitin Test” Reagent: Antigen – freezedried/lyophilized Schistosoma japonicum eggs Specimen – Patient Serum Positive result: bleb formation Liquefied petrolatum/wax/paraffin – used to avoid evaporation and to seal the preparation Glass beads/nail polish – to elevate the preparation *Incubate at 36oC for 24 hours and examine under microscope for blebs
Treatment: Praziquantel 2. Schistosoma mansoni Common Name: Manson’s Blood Fluke FH: Man IH 1: Biomphalaria spp. Habitat: Inferior mesenteric veins of the large intestines, colon, rectum Diagnostic Stage: Ova in stool * Take note of rules for MoT (skin penetration) and IS (fork-tailed cercaria) *Endemic in Africa and South America Morphology: Adult: Male: o Prominent Integumentation o 8-9 testes, the most number of testes among Schistosomes Female: o Ovary – at the anterior part of the body o Uterus – 1-4 eggs Egg: Diagnostic Stage With lateral spine Life Cycle Notes: Same as S. japonicum; the only difference is the habitat of the adult Pathology:
Intestinal bilharziasis Diagnosis: COPT, Stool Exam, Egg Hatching Technique Treatment: Praziquantel 3. Schistosoma haematobium Common Name: Vesical Blood Fluke FH: Man IH 1: Bulinus spp. Habitat: Vesical, Prostatic, Uterine, Venous Plexuses of Urinary Bladder///Vesical Plexuses of the Venous Circulation Diagnostic Stage: Ova in urine *Urine is red in heavy Schistosoma haematobium infection, unlike in heavy filarial infections where urine is milky/turbid. *Endemic in Middle East and Africa Morphology: Adult: Male: o 4-5 testes o Fine tuberculations Female: o Ovary is in the posterior end o 20-3o eggs in the uterus Egg: With prominent terminal spine Life Cycle Notes: Same as S. japonicum and S. mansoni, except for habitat Discharged in urine instead of feces Pathology: Urinary Bilharziasis, Egyptian Schistosomiasis Diagnosis: Urine Exam, COPT, egg hatching technique Centrifuge urine, and look for eggs in the sediments. Concentration technique known as Nucleopore Filtration Technique may be used Treatment: Praziquantel
D. LUNG FLUKE Paragonimus westermani Common Name: Oriental Lung Fluke FH: Man IH 1: Antemelania asperata IH 2: Sundathelphusa philippina (crab, one claw is bigger) Habitat: Lungs (encapsulated in pairs) Diagnostic Stage: Ova in sputum/stool *Old name of Antemelania asperata is Broatia asperata *Endemic in Bicol, and one is given a direct sputum smear in addition to Acid Fast staining when there are TB-like symptoms *Prawns - paratenic host Morphology: Adult: Reddish, spoon or coffee bean shaped Rounded anterior, ovoid posterior Testes – Deeply lobed obliquely in tandem Large, broad and flat body Wavy intestinal ceca Spines in the integument Egg: Ovoid, with flat, WIDE operculum (unlike in Heterophid eggs) With abopercular thickening opposite of operculum Brownish operculum Life Cycle Notes: Eggs are excreted unembroynated in the feces and/or sputum Metacercaria excyst in the duodenum The worms can also reach other organs and tissues such as the brain and striated muscles. However, when this takes place, completion of the life cycles is not achieved, because the eggs laid cannot exit these sites. Pathology: TB-like symptoms Hemoptysis – expectorating/coughing blood which originated from the lungs
(differentiate with hematemesis, in which blood is from the GI tract) Jacksonial epilepsy Pulmonary Distomiasis Cerebral Paragonimiasis, when there is migration to the brain
Adult: Ruffle border 2 notched testes 1 notched ovary Egg: Similar to D. dendriticum
Diagnosis: Sputum Exam o 3X in different days, preferably in the morning o Use NaOH, 10-30% HCl or NAL-C as mucolytic agent (1 part sputum, 9 parts digestant) o Centrifuge, then look for eggs in the sediment Stool Exam o Eggs are present when sputum is swallowed o Can also confirm P. westermani Biopsy and Autopsy – the only way to remove or recover adult worms
Pathology: Eurytremiasis – destruction of pancreas; diabetes mellitus Diagnosis: Same as previous Treatment: Praziquantel
Treatment: Praziquantel, Bithionol (will kill the adult worm and cause fibrosis) E. PANCREATIC FLUKE Eurytrema pancreaticum (lab notes only, wala sa book and CDC) Common Name: Pancreatic Fluke FH: Hogs, cattle (Man is AH) IH 1: Macrochlamys indica IH 2: Technomyrmex deterquens (ant) or grasshopper Habitat: Pancreatic duct, biliary passages, gallbladder
Morphology:
---------TEMPLATE (for reviewing) Common Name: FH: IH 1: IH 2: Habitat: Diagnostic Stage: * Morphology: Adult: Egg: Life Cycle Notes: Pathology: Diagnosis: Treatment:
