TREMATODES

GENERAL CHARACTERISTICS Also known as flukes Leaf-like 2 suckers (oral & ventral) Snail is always the 1st intermediate host Two intermediate hosts except schistosomes Hermaphroditic except schistosomes Operculated eggs except schistosomes Infective stage metacercaria except schistosomes(cercaria)

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Paragonimus westermani Common Name: Lung fluke M.O.T. : Ingestion Infectious stage: metecercaria 1st IH: Snail (Antemelania asperata/ductylus) 2nd IH: Crab (fresh H2O crab)(Sundathelphusa philippina) Definitive Host: Humans & fish eating mammals Location: lungs

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Eggs are excreted unembryonated in sputum/feces

embryonated in the external environment

miracidia hatches and penetrates the 1st I.H.(snail) undergoes developmental stages inside (sporocysts,rediae,cercariae)

cercaria invade the 2nd I.H. (crustacean) where they develop further into metacercaria

human infection occurs by eating undercooked/raw/pickled infected crustaceans(crabs/crayfish)

metacercaria excyst in the duodenum-->intestinal wall--> peritoneal cavity-->abdominal wall-->diaphragm--> lungs where they become adults

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Disease: Paragonimiasis Breathing difficulty, chronic cough, sputum w/ blood streaks Migration to the heart may cause heart failure Migration to the brain may cause blindness, paralysis, disequilibrium,

sudden onset of epilepsy. Adults in lungs stimulate inflammatory responses resulting in granulomas.

egg in lung biopsy

Sundathelphusa philippina

DIAGNOSIS, TREATMENT & PREVENTION Diagnosis: Eggs in sputum or in stool

Eggs closely resembles D.latum Unlike D.latum eggs, P.westermani eggs have opercular shoulders

and a marked thickening at the abopercular end Adults may be found in lungs

Treatment: Praziquantel Prevention:

Avoid eating undercooked / raw crustaceans Cook food properly

Fasciolopsis buskiCommon Name: Giant intestinal flukeM.O.T. : IngestionInfectious stage: metecercaria1st IH: Snail (Segmentina/Hippeutis)2nd IH: Aquatic vegetation : Lotus(Nympnea lotus)

Water caltrop(Trapabiconis)Definitive Host: Humans & pigsLocation: small intestinesProbably the largest trematode specie to infect humans

immature eggs discharged into stool

eggs embryonate in the external environment

miracidia hatches and penetrates 1st I.H.

inside, they further develop into several stages (sporocyst, rediae,cercariae)

cercariae are released from the snail and encyst as metacercaia in aquatic plants

mammals get infected by eating the aquatic plants

metacercaia excyst in duodenum and attaches to intestinal wall and become adults

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LIFE CYCLE

Disease: faciolopsiasis Symptoms may include nausea and chronic diarrhea,

abdominal pain, fever May obstruct intestines Interfere with food absorption Most infections are light and asymptomatic

Hippeutis snail

DIAGNOSIS, TREATMENT & PREVENTION Diagnosis: Eggs in stool

Eggs are large, brown, oval thin-shelled with inconspicuous operculum Closely resembles that of Faciola sp. eggs and are difficult to differentiate

Treatment: praziquantel Prevention:

Cook all aquatic plants well before eating them (in boiling water) prevent fecal contamination (from humans or pigs) of water where aquatic

plants are grown. Avoid eating raw / undercooked aquatic plants in endemic areas

Faciola hepatica & giganticaCommon Name: Temperate(hepatica) liver fluke Tropical(gigantica) liver flukeM.O.T. : Ingestion (water or aquatic vegetation)Infectious stage: metecercaria1st IH: Aquatic snails (Lymnaea)2nd IH: Aquatic vegetation : kangkong(Ipomea obscura)

Water cress(Nasturtium officinale)Definitive Host: Humans & herbivorous animalsLocation: liversize: hepatica(30mmx13mm), gigantica(upto 75mm)

Immature eggs discharged in the biliary ducts & into the stool

eggs become embryonated in external environment

miracidia are released and penetrates 1st I.H.

parasite undergoes several developmental stages (sporocyst, rediae, cercariae)

cercaria are released and encyst on aquatic vegetation as metacercaria

mammals acquire infection by ingestion of these vegetation

after ingestion, in humans, metacercaria migrate towards the biliary ducts where they develop into adults

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LIFE CYCLE

Disease: Fascioliasis Feeds on cells of the liver and blood Adults cause edema and inflammation of bile duct Causes anemia, jaundice, cirrhosis similar to other liver

diseases

DIAGNOSIS, TREATMENT & PREVENTION Diagnosis: Eggs in feces, History, ELISA Treatment: Triclabendaole drug of choice for both humans &

livestock Prevention:

Individual people can protect themselves by not eating raw watercress and other water plants

travelers to areas with poor sanitation should avoid food and water that might be contaminated

Vegetables grown in fields that might have been irrigated with polluted water should be thoroughly cooked

Clonorchis sinensis Common Name: Chinese liver fluke or Oriental liver fluke M.O.T. : Ingestion (water or aquatic vegetation) Infectious stage: metecercaria 1st IH: snail(Parafossarulus,Bulimus,Alocinma) 2nd IH: fish (Cyprinidae:carps/crayfish)

Salted, pickled or dried Definitive Host:Humans, pigs, dogs, cats and other fish eating mammal Location: Liver Testes: Dendritic/Branchy

Embryonated eggs are dischared from biliary tract and into stool

eggs are ingested by snail(1st IH)

parasite undergoes developental stages (miracidia,sporocyst, rediae, cercaiae)

cercaria are released and attach in the skin/flesh of fresh water fish where they encyst as metacercaria

fish are eaten undercooked/raw by humans

metacercaria excyst in duodenum and ascends the biliary tract

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LIFE CYCLE

Disease: Clonorchiasis, cholangiocarcinoma Causes erosion of epithelium lining ducts Most damage is due to immune response in the liver Eggs are surrounded by granulomas, reducing liver function Frequently causes liver cance Jaundice, indigestion, diarrhea, hepatomegaly, weight loss,

ascites(accumulation of fluid in abdominal cavity) Severity of infection depends on the number of adult worms

DIAGNOSIS, TREATMENT & PREVENTION Diagnosis: Eggs in feces

Old fashioned light bulb Treatment: Praziquantel Prevention:

Do not eat raw or undercooked freshwater fish.

Opisthorchis sp. Opistorchis Viverrini (southeast asian liver fluke) Opistorchis Felinus (cat liver fluke) M.O.T. : Ingestion Infectious stage: metecercaria 1st IH: snail (Bithynia) 2nd IH: fish (Cypridae, Cobitidae) Definitive Host: Humans & other fish eating

mammals Similar morphology, lifecycle & pathology to

Clonorchis sinensis Testes: Round, circular, lobulated

Disease: Opisthorchiasis indistinguishable with clonorchiasis (caused by C.sinensis)

the disease is thus referred to as clonorchiasis mostly asymtomatic pathogenisis, signs and symptoms are similar that of

C.sinensis

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DIAGNOSIS, TREATMENT & PREVENTION Diagnosis: Eggs in stool

indistinguishable to those of C.sinensis Treatment: Praziquantel drug of choice Prevention: that of Clonorchis sinensis

Heterophyes heterophyes Common Name: small intestinal fluke M.O.T. : Ingestion (encysted metacercaria in fish) Infectious stage: metecercaria 1st IH: aquatic snails (Thiara riquetti) 2nd IH: Fish Definitive Host: Humans & other fish-eating mammals Location: small intestine Other heterophids

Metagonimus Haplorchis

embryonated egg with developed miracidium are passed in feces

ingested by 1st I.H.(snail) eggs hatch and release miracidia

w/c undergoes several developmental stages

cercaria are released and penetrate the skin of fresh water fish and encyst as metacercaria in its tissue

Host becomes infected by ingesting undercooked/raw fish

metacercaria excyst and attaches to the small intestine

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LIFE CYCLE

Disease: HeterophyiasisMild inflammatory responseHeavy infection may damage the mucosa and penetrate it and

migration can occur to other areas(heart, brain lymph nodes, etc.)

DIAGNOSIS, TREATMENT & PREVENTION Diagnosis: Eggs in stool

Resembles that of opistorchis & clonorchis Treatment: Praziquantel Prevention:

Care in ingesting raw, or undercooked fish. Incompletely salted or pickled fish also are infectious

Echinostoma ilocanumCommon Name: no known common name

Wide variety of Echinostoma speciesM.O.T. : Ingestion (water or aquatic vegetation)Infectious stage: metecercaria1st IH: snail (Gyraulus, Hippeutis)2nd IH: snail: kuhol(Pila luzonica)

susong papang(Vivipara angularis)Definitive Host: Humans & aquatic birdsLocation: intestines or bile duct

unembryonated eggs passed out in feces

develops in the external environment

miracidia hatches and penetrates snail and undergoes several developmental stages

cercaria is released and enters the second host

the second I.H is then eaten by humans or birds

metacercaia excyst in the duodenum

adults reside in the small intestine

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LIFE CYCLE

Disease: Echinostomiasisheavy infections, nausea, vomiting, diarrhea, fever and

abdominal pain may occur.Catarrhal inflammation often occurs due to the penetration of

the sharp-spined collar into the intestinal mucosaMost don’t show symptoms

DIAGNOSIS, TREATMENT & PREVENTION Diagnosis: Eggs in stool

Large in size Refractile dots may be seen Specie differentiation requires morphological study of adults

Treatment: Praziquantel drug most commonly used for treatment Prevention:

Avoid eating undercooked / raw snails

SCHISTOSOMES

Blood Flukes

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Schistosoma japonicum

Common Name: oriental blood fluke M.O.T. : skin penetration Infectious stage: cercaria 1st IH: snail(oncomelania quadrasi) Definitive Host: humans, wild animals Location: veins of small intestine Has 3 openings: oral, ventral & gonophore *more pathogenic than other sp.

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Schistosoma mansoni

Common Name: Intestinal schistosoma M.O.T. : skin penetration Infectious stage: cercaria 1st IH: snail Definitive Host: humans, wild animals Location: portal veins of large intestine

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Schistosoma haematobium Common Name: Urinary schistosome M.O.T. : skin penetration Infectious stage: cercaria 1st IH: aquatic snail Definitive Host: humans (host specific) Location: veins of the urinary bladder, urethra, ureters

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DISEASESchistosomiasis/ Bilharziasis

Migratory- usually asymptomatic, cercaria migrates to its right place

Acute- adults start making eggs, gastrointestinal discomfort, muscle aches, headache, fatigue, fever, chills

Chronic- occurs where parasite is endemic, ascites, hepatomegaly, splenomegaly, dwarfism, eggs may lodge in the brain causing neurological damage

Granulumatous reaction(granulomatosis) – due to the spinesSwimmers itch- derma.infxn due to penetration of cercaria

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DIAGNOSIS &TREATMENTDIAGNOSIS

EGGS:S. japonicum- minute lateral spineS. haematobium- large terminal spine (eggs found in urine)S. mansoni- large lateral spine

SEROLOGICAL TESTSCOPTELISA

TREATMENTPRAZIQUANTEL

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S. mansoni

S.japonicum

S.haematobium

PREVENTION & CONTROLPREVENTION:Avoid swimming in bodies of water in endemic areasKilling of snail hostProper sanitation

CONTROL:EDUCATIONVECTOR CONTROL

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OTHER SCHISTOSOMES S. mekongi – smaller than S. japonicum S. intercalatum- like S. haematobium but bent terminal spine

Acid fast

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