TREMATODES

General Characteristics Flattened dorsally, leaf-like, elongated and unsegmented ovoid, conical or cylindrical depending upon the state of contraction vary in size from less than 1 mm to several cm covered by non-cellular integument, which maybe covered with

spines or tubercles Integument: absorption of carbohydrates and may also serve for

secretion of excess metabolites and mucus. most distinguishing characteristic of adult trematodes: oral suckers:

attachment to the host. o oral sucker: anterior end

o ventral sucker or acetabulum: larger, blind, located at

ventral surface; posterior to the oral sucker Digestive system:

o Incomplete

o with mouth

o no anus

o muscular, globular pharynx extends from the mouth in the

oral sucker to a short narrow esophaguso Below the esophagus, the intestine bifurcates into two

o Intestines:

branched/dendritic simple

Excretory system:o diffusely scattered flame cells or solenocytes

o capillaries, collecting tubules, bladder and excretory pore

o The terminal flame cell is a hollow cell with tuft of cilia.

Primitive Nervous system:o two lateral ganglia in the region of pharynx connected by

dorsal commisures. o From each ganglia arise anterior and posterior longitudinal

nerve trunks connected by numerous commisures. Hermaphroditic (all trematodes are hermaphroditic except the

BLOOD FLUKES)LIFECYCLE: 1) adult fluke lays eggs (passed in stool)

2) eggs in water à miracidium (ciliated larva) 3) miracidium ingested by 1st IH (snail) à sporocyst 4) sporocyst à redia à cercaria (leaves snail) à encysts as metacercaria 5) metacercaria: 2nd IH: water plants, fish, crustacean (crab/crayfish) 6) metacercaria in 2nd IH is consumed by man

Classification of TrematodesAccording to habitat

Portal vein (Blood Flukes)Schistosoma japonicum- Oriental blood flukeSchistosoma haematobium - Vesical blood flukeSchistosoma mansoni - Manson’s blood flukeLungsParagonimus westermani – Oriental lung flukeLiver and bile passagesFasciola hepatica – Giant or Sheep liver flukeClonorchis sinensis – Chinese or Oriental liver flukeOpistorchis felineus – Cat liver flukeIntestineFasciolopsis buski – Giant intestinal flukeEchinostoma ilocanum – Garrison’s flukeHeterophyds Heterophyes heterophyes – Von Siebold flukeMetagonimus yokogawai Haplorchis taichu BLOOD FLUKES: Schistosoma japonicumCN: Oriental Blood Fluke Habitat: superior mesenteric vein of Small IntestinesIS: forked tail cercaria MOT: skin penetrationFinal Hosts: ManDisease caused:

Oriental schistosomiasis, Intestinal schistosomiasis, Hepatic schistosomiasis Schistosomiasis japonicaKatayama’s disease

Schistosoma mansoniCN: Manson’s Blood Fluke

Habitat: mesenteric vein of Large IntestinesIS: forked tail cercaria MOT: skin penetrationFinal Hosts: ManDisease caused:

Schistosomiasis mansoni Rectal/Intestinal schistosomiasis

Schistosomia hematobium CN: Vesical Blood Fluke Habitat: portal vein of the urinary bladderIS: forked tail cercaria MOT: skin penetrationFinal Hosts: ManDisease caused:

Vesical schistosomiasis Bilharziasis Urinary schistosomiasis

MORPHOLOGYSchistosoma japonicum adult is provided with smooth tuberculations. The male have 6 – 9 testes arranged in rows. The ovary of the female lies somewhat behind the mid plane of the body and the uterus can have 50 eggs at one time Schistosoma mansoni is provided with coarse tuberculations. Male has 6 – 8 testes while the ovary of the female is situated in the anterior half of the body. The uterus is short with 20 – 40 eggs. Schistosoma haematobium is provided with fine tuberculations, wherein the ventral sucker is larger than the oral sucker. The number of testes in male is 4 – 5 . The ovary of the female is posteriorly located. The number of eggs in the uterus is 20 – 100.

EGGS:Schistosoma japonicum eggs are ovoidal, non operculated. 70 – 90 micra by 50 – 65 micra. A rudimentary or minute lateral spine is present. Schistosoma mansoni eggs are elongated, non operculated.114 – 175 micra with transparent shell and a prominent lateral spine

 Schistosoma haematobium eggs are elongated, non-operculated, light yellowish brown and possess a distinct terminal spine

LIFE CYCLE Eggs à miracidia (ciliated larva) à sporocyst (1st IH: snail) à redia à cercaria (leaves snail) à metacercaria (2nd IH: fresh water plant, fish, crustacean) à man

PATHOGENESIS

Symptoms associated with schistosomiasis include weakness, diarrhea, hepatosplenomegaly, and carcinoma of the intestine, liver, uterus and urinary bladder

Treatment: Praziquantel & Niridazole

Schistosoma japonicum and Schistosoma mansoni Site of entry: Pruritus and rashes = “swimmer’s itch” Migration of the adolescent in the lungs: pneumonitis (Pulmonary

schistosomiasis.) Deposition of eggs in the tissues: irritation and formation of ulcers

in the mucosa leading to the escape of the eggs into the intestinal lumen.

Ulceration in mucosa: diarrhea or dysentery seen in acute schistosomiasis

Granuloma of affected tissue and organ is also evident: o obstructions to the pulmonary circulation o formation of pseudotubercle in affected organs/tissues

maybe observedo Schistosomiasis japonica depending on the major sites of

eggs deposition maybe hepato-intestinal, hepato-splenic or pulmonary.The clinical course of infection is divided into three progressive stages:

Incubation: corresponding to the period from the cercarial penetration and schistosomular migration to the time the flukes mature

period of early egg deposition and extrusion period of tissue proliferation

Schistosoma hematobium

lives primarily in the pelvic veins: o eggs are primarily deposited in the vessical plexus =

lesions in the urinary bladder, genitalia (seminal vesicle, vulva, cervix and vaginal walls)

Uric acid and oxalate crystals, phospate deposits, eggs, blood clots, mucus and pus maybe present in urine

** most characteristic symptom is hematuria (blood in the urine) mucosal surfaces become inflamed = painful micturation/urination

and a constant urinary residual. Pain in the suprapubic region and weakness may occur.

LUNG FLUKE:Paragonimus westermani

CN: Oriental Lung FlukeHabitat: lungs1st IH: snail = Antemelania asperata (formerly Brotia asperata), Antemelania dactylus 2nd IH: crab = Sundathelpusa philippina (formerly Parathelpusa grapsoides)Infective Stage: encysted metacercaria within 2nd IHMOT: ingestion of metacercaria in 2nd IHFinal Hosts: ManDisease caused:

Paragonimiasis Pulmonary distosomiasis Endemic hemoptysis

MorphologyAdult worm:

reddish-brown 7 – 12 mm length, 4 –6 mm in width and 3.5 – 5 mm in thickness cuticle is spinous oral and ventral suckers are of equal size intestinal ceca are simple two testes are deeply lobed, situated opposite each other ovary has 6 unbranched lobes and is anterior to the testes shape of adult: When Active - Spoon-shaped, with one end contracted and the

other elongated When preserved - Oval, flattened, coffee bean shaped

Persist in humans for as long as 20 years or more.Animal reservoir hosts of this parasite include: dogs, cats, field rats and other rodents.

LIFE CYCLE

cercaria leaves snail in about 13 weeks and penetrate 2nd IH: freshwater crab or crayfish = Sundathelphusa philippina (formerly Parathelphusa grapsoides)

** cercaria penetrates through the soft parts of the body of the crab and encysts as metacercaria in the gills, legs, body muscles or the viscera

** definitive host acquires the infection by ingestion of raw or insufficiently cooked infected crabs

upon ingestion: excysted metacercaria pass through the duodenal wall into the abdominal cavity

adolescent worms: burrows through diaphragm, à enter the pleural cavity and in 20 days reach the lungs and become adult in 5 – 6 weeks

in prolonged migration: adolescent worms may o remain for long period in the peritoneum o enter and leave the livero lodged in organs (rare cases)

Pathogenesis : PARAGONIMIASISLungs:

o parasite causes development of a fibrous tissue capsule

o FIBROUS TISSUE CAPSULE: (within this cyst) = blood

tinged, purulent material containing eggs

o Early Infection: dry cough

o Later part: bloodstained, rusty brown sputum (most

pronounced on rising in the morning)

o Pulmonary pain and hemoptysis occurs

o ** Along with these symptoms, the patient may experience

fever, sweating, chest pains, cough = MIMICS symptoms of PTB

o ** hard to distinguish from pulmonary tuberculosis,

pneumonia and bronchitis

Cyst formation:

o **localize in the abdominal wall, abdominal cavity,

mesenteric lymph nodes, omentum, pericardium, and myocardium and in intestinal wall

o abdominal pain, rigidity and tenderness

In the brain:Jacksonian epilepsy Visual disturbances Worms situated in the subcutaneous tissue cause creeping tumor

Identification of eggs in:SputumBronchial washingFeces

Treatment:Praziquantel, Emetine hydrochloride &Bithionol

LIVER FLUKES:Fasciola hepatica

CN: Sheep’s Liver Fluke, Giant Liver Fluke Habitat: liver, bile ducts1st IH: snail = Lymnae philippinensis, Lymnae swinhoe and Lymnae truncatula 2nd IH: aquatic plantsInfective Stage: forked tail cercaria MOT: ingestion of metacercaria in 2nd IH: aquatic vegatation Final Hosts: ManDisease caused:

Sheep Liver RotFascioliasis

Morphologylargest fluke infecting man

Adult: large, flat, leaf-like 20 – 50 mm in length and 6 – 12 mm in width

anterior end: conical projection (cephalic cone) and a characteristic shouldered appearance is also observed **which serve as distinguishing features

posterior end: broadly pointedo two relatively small suckers

o intestinal ceca are highly branched or dendritic.

o two deeply branched or dendritic testes

o single dendritic ovary

Related species: Fasciola gigantica • which commonly infects cattle, water buffaloes and carabaos, is

larger, more lanceolate than F. hepatica. • 30 – 70 mm in length and 3 – 11 mm in width• shorter cephalic cone, less developed shoulders, a larger ventral

sucker and the intestinal ceca is more branched.EGGS

large, ovoid, operculated, yellowish brown well rounded posterior end characteristically hen-egg shaped 140 – 180 by 80 – 100 microns and is unsegmented at oviposition

LIFECYCLE eggs are passed out in the feces and mature in water miracidium is formed within 9 – 15 days. miracidium escapes through the operculum and invade the 1st

intermediate host: snails = o Lymnae philippinensis

o Lymnae swinhoe

o Lymnae truncatula

Inside the snail intermediate host:

o sporocyst à one or two generations of rediae à

cercaria. Cercaria: emerge from the snail and attach by way of their oral

sucker on the surface of 2ng IH: aquatic vegetation(watercress) à where they develop into metacercaria.

o Ipomea obscura or kangkong

o Ipomea reptans or morning glory  

Definitive Host: o metacercaria excyst in the duodenum, liberating the

juvenile flukes à penetrate intestinal wall à peritoneal

cavity à viscera à liver capsule à burrows through the

liver parenchyma à bile ducts where it matures in 3 – 4 months

o The adult worm survives for as long as 11 years in

definitive host.This parasite infects herbivorous mammals like sheep, cattle, deer and rabbits while man serve as occasional host. The adult worm inhabits the biliary passages in the liver. On the other hand the first intermediate host of Fasciola gigantica is Lymnae rubiginosa. Pathogenesis: Fascioliasis

Latent or chronic phase period when the parasite has already settled in the bile

ducts Clinical manifestations:

adult causes obstruction of bile ducts inflammation on the epithelium of the bile duct

stimulating pipestem fibrosis Pharyngeal Fascioliasis or Halzoun:

result from ingestion of raw sheep liver or goat liver containing the adult parasite

attachment of the worm in the pharyngeal mucosa may result to asphyxiation (suffocation).

Diagnosis: Fascioliasis recovery of the eggs in the patient’s stool Fasciola eggs maybe present in stool of individual who has earlier

consumed infected animal liver (False fascioliasis) ruled out by keeping the patient on a liver free diet for three to 7

days before another stool examination is done. Immunodiagnostic tests:

o CFT, precipitin test, immunoelectrophoresis, counter

immunoelectrophoresis o FAST (Falcon Assay Screening Test)-EIA alone or in

combination with EITB can detect F. hepatica excretory-secretory antigens in serum

o EIA with somatic antigen or excretory-secretory antigens

from F. gigantica or F. hepatica (especially excretory-secretory products), yield high sensitivity, including

detection of reactive IgM in acute fascioliasis and confirmation by enzyme-linked immunoelectrotransfer blot (EITB).

Treatment: Bithionol LIVER FLUKES:Clonorchis sinensis

CN: Chinese Liver Fluke, Oriental Liver Fluke Habitat: bile ducts; gall bladder, pancreatic duct (heavy infection)

** NOT FOUND IN DUODENUM because it can only survive the presence of digestive juices for only a few hours

1st IH: snail = Parafossarulus manchoricus 2nd IH: = Ctenopharyngodon idellus (fish), Caridina nilotica gracilipes (shrimp) Infective Stage: metacercaria in 2nd IHDiagnostic Stage: egg/ova in stool MOT: ingestion of metacercaria in 2nd IH:Final Hosts: Man, dogs, cats, pigs, ducks (rare occasion)

** a parasite of fish-eating mammals Disease caused:

Clonorchiasis 1stIH:Parafossarulus manchoricus snails that live in fish culture ponds, lakes, swamps, and sluggish parts of the river or small streams 2ndIH: Ctenopharyngodon idellus = aka Grass Carp: herbivorous freshwater fish

Caridina nilotica gracilipes = aka Freshwater shrimpAdult:

flat, elongated, aspinous, and transparent gray tapering anteriorly and somewhat rounded posteriorly 8 – 25 mm in length and 1.5 – 5 mm in width. ventral sucker is smaller than the oral sucker. intestinal ceca: long, simple extending to the posterior end two deeply branched testes in tandem formation are

situated in the posterior part of the body single ovary is relatively small with three lobes and located

anterior to the testesThe entire life cycle can be completed in three months. The life span of the adult is 15 – 20 years.LIFE CYCLE:

free-swimming cercaria dies within 24 – 48 hours unless ingested by freshwater fish (2nd IH): Ctenopharyngodon idellus, Caridina nilotica gracilipes

Inside 2nd IH: o metacercaria encyst chiefly in the muscles and

subcutaneous tissues, less often on the scales, fins and gills of fish.

Infected fish is eaten by the mammalian definitive host:o metacercaria excyst in the duodenum

o In the human duodenum:

outer wall is dissolved by trypsin inner layer is ruptured by the activity of the

metacercaria freed larva migrates to:

common bile duct distal biliary ducts: maturation in a

month

Pathogenesis: Clonorchiasis Eggs are associated with formation of gallstones Diet affects chronic infections:

o Increased intake of dimethylnitrosamines (in fermented

fish) usually leads to cholangiocarcinoma (neoplasia of the liver)

Symptoms: o fatigue, weakness, weight loss, abdominal distress and

altered appetiteo fever, enlargement and tenderness of the liver and

eosinophilia (acute infection)o anemia, liver enlargement, slight jaundice, edema and

diarrhea (heavy infection) Diagnosis:

o Identification of characteristic eggs in the feces

o Immunodiagnostic test and liver scan

Treatment: Praziquantel LIVER FLUKES:Opistorchis felineusCN: Cat Liver Fluke

Habitat: biliary passages1st IH: snail = Bythinia leachi 2nd IH fish: = Idus melanotus, Tinca tinca, and Cyprinus carpio, Barbus

barbus Infective Stage: metacercaria in 2nd IHDiagnostic Stage: egg/ova in stool MOT: ingestion of metacercaria in 2nd IHFinal Hosts: ManDisease caused:

Opistorchiasis felineus Adult:

reddish yellow Lancet shaped 7 –12 mm in length and 1.5 – 3 mm in width intestinal ceca is simple two testes are lobate and arranged obliquely in tandem (in

pairs) oral sucker is smaller than the ventral sucker single ovary is lobed

A closely related species infecting man: Opistorchis viverrini = differentiated from Opistorchis felineus:- ovary and testes are nearer to each other, both of which are more deeply lobulated - testes are obliquely arranged

EGGS yellowish-brown, ovoid and is smaller than Clonorchis sinensis ova With operculum that sits on the thickened rim and a minute

aboperculum is also present o LIFE CYCLE: Same as Clonorchis sinensis differs only in

the specific species as intermediate hosts o Pathogenesis: Opistochiasis felineus

clinical involvement depends largely on worm burden and the duration of the infection.

Moderate infections: (about 100-1000 worms) o enlargement of the liver, passive congestion of the spleen,

with icterus and local eosinophilia in the wall of the bile ducts

In heavier infections: o Worms found in the pancreas and the gall bladder and the

patient suffers from digestive disturbances

o Bile stones maybe formed around the parasite eggs

Opistorchis has been linked to carcinoma of the bile ducts and the liver

Diagnosis: identification of egg/ova in the stoolTreatment: Praziquantel

INTESTINAL FLUKES:Fasciolopsis buski

CN: Giant Intestinal Fluke Habitat: duodenum and jejunum1st IH: snail = Segmentina trochoideus or Hippeutis umbilicalis 2nd IH aquatic plants: = Trapa bicornis (water caltrop), Eliocharis tuberosa (water chestnut), Ipomea aquatica (water morning glory) and Nymphae lotus (lotus) Infective Stage: metacercaria in 2nd IHDiagnostic Stage: egg/ova in stool MOT: ingestion of metacercaria in 2nd IHFinal Hosts: ManDisease caused:

Fasciolopsiasis Morphology

20 – 70 mm in length, 8 – 20 mm in width elongated and oval in shape oral sucker is about one- fourth the size of the nearby ventral

sucker. This fluke resembles Fasciola hepatica:

o Differentiation:

No cephalic cone shoulder and the intestinal ceca are simple but

wavy and unbranched testes are highly dendritic in tandem formation single ovary is branched

EGGS yellowish ellipsoidal thin-shelled, rounded at both ends and operculated   80 – 85 micra

The adult inhabits the small intestine particularly the duodenum and the jejunum. It is either attached to the intestinal mucosa by the ventral sucker or lies buried in the mucous secretions. Each adult produces an average of 16,000 eggs per day.

LIFECYCLE: Each adult produces an average of 16,000 eggs per day. egg is undeveloped when passed in the feces In water: eggs à miracidium (3 – 7 weeks) Miracidium penetrate the 1st IH (snail): Segmentina trochoideus

or Hippeutis umbilicalis In the snail intermediate host:

o Miracidium à sporocyst à rediae 1 à rediae 2 à

cercaria Cercaria will leave the body of the 1st intermediate host (4 – 7

weeks) encyst on the surfaces of the 2nd IH (aquatic plants): Trapa bicornis (water caltrop), Eliocharis tuberosa (water chestnut), Ipomea aquatica (water morning glory) and Nymphae lotus (lotus)

Metacercaria in 2nd IH are ingested by man metacercaria excyst in the duodenum and attach themselves

to the intestinal wall and becomes an adult worm in about three months.

Pathogenesis: FasciolopsiasisPathology maybe due to the following: Traumatic

inflammation and ulceration at the site of attachment à increase mucus secretion and minimal bleedingEpigastric pain, nausea and diarrhea may occur especially in the morning.

ObstructiveIn heavy infections: edema and partial intestinal obstruction due to the large size of the worm

ToxicIntoxication occurs: absorption of the worms excess metabolites and excretory by-products which become systematic upon absorptiongeneralized toxic and allergic symptomsprofound intoxication may result in death

Treatment: Praziquantel, Niclosamide,Tetrachloroethylene,Hexylresorcinol,Dichlorophen INTESTINAL FLUKES:Echinostoma spp.

Echinostoma:

medium sized adult worms: unique due to the presence of collar of spines around the oral sucker

Many species have been reported in man and are differentiated on the basis of number of spines and number of lobes in testes In the Philippines:

Echinostoma ilocanum Echinostoma malayanum

Echinostoma ilocanumCN: Garrison’s FlukeHabitat: small intestines1st IH: snail = Gyraulus convexiusculus or Hippeutis umbilicalis

(IN THE PHILIPPINES)2nd IH snail = Pila luzonica or kuhol and Vivipara angularis or susong pampang Infective Stage: metacercaria in 2nd IHDiagnostic Stage: egg/ova in stoolMOT: ingestion of metacercaria in 2nd IHFinal Hosts: ManDisease caused:

Human Echinostomiasis

Echinostoma malayanumHabitat: small intestines1st IH: snail = unkown (IN THE PHILIPPINES)2nd IH snail = Lymnae cumingiana or birabid (formerly Bullastra cumingiana), Radix quadrasi and Physastra hungerfordiana Infective Stage: metacercaria in 2nd IHDiagnostic Stage: egg/ova in stool MOT: ingestion of metacercaria in 2nd IHFinal Hosts: ManDisease caused:

Human Echinostomiasis Morphology: Echinostoma ilocanum

reddish gray 2.5 – 6.5 mm in length, 1 – 1.5 mm in width anterior end: horseshoe-shaped collar of spines (Collarette of

spines) = circumoral disk surrounded with 49 – 51 spines in two rows

oral sucker found at center of this disk Testes: bilobed, in tandem formation Ovary: globular, anterior to the testes

Morphology: Echinostoma malayanum

5 – 12 mm in length and 2 – 3 mm in width Elongated, bluntly rounded ends 43 – 45 collar of spines multilobulated testes (6 – 9 lobes) in tandem formation ovary is small, rounded or ovalEchinostoma ilocanum ova:

86–116 micra by 58–69 micra straw-colored, operculated ovoidal and with

characteristic germ ballEchinostoma malayanum ova:

Larger than Echinostoma ilocanum 120 – 130 micra by 80 – 90 micra

operculated with characteristic germ ball LIFECYCLE:

immature eggs are passed out with the fecesova mature within 6 – 15 days à miracidium enters the 1st IH:

for Echinostoma ilocanum: Gyraulus convexiusculus or Hippeutis umbilicalis for Echinostoma malayanum: unknown

Inside the snail intermediate host: miracidium à redia 1 à redia 2 à cercaria Cercaria escape from the snail 42 – 50 days to infect the 2nd IH:

also a snail: Echinostoma ilocanum:

Pila luzonica or kuhol Vivipara angularis or susong pampang

Echinostoma malayanum:Lymnae cumingiana Radix quadrasi Physastra hungerfordiana

cercaria à metacercaria man ingests metacercaria by eating infected snailmetacercaria excyst in the duodenum and the adult fluke attaches itself to the intestinal wall

Pathogenesis: Echinostomiasis little damage to the intestinal mucosa: inflammation at the site of

attachment In heavy infections: diarrhea, bloody diarrhea abdominal pain General intoxication: absorption of the metabolites of the worms Diagnosis: identification of eggs/ova in stool

Treatment: Praziquantel & HexylresorcinolINTESTINAL FLUKES:HeterophydsFamily Heterophydiae:

Heterophyes heterophyes Metagonimus yokogawai Haplorchis taichu

Adult Heterophyds:• elongated, oval or pyriform in shape• the smallest yet the deadliest: less than 2 mm in length• HABITAT: Small Intestines

Morphology:Heterophyes heterophyesCN: Von Siebold’s Fluke

Adult: Grayish smallest fluke of man: 1.3 by 0.5 mm oral sucker is very small ventral sucker is large, situated in the anterior middle-third of the

body conspicuous genital sucker (gonotyle) found in the lateral

posterior border of the ventral sucker two testes: ovoid, side by side in the posterior fifth of the body ovary: subglobuse, anterior to the testes

Morphology:Metagonimus yokogawai

Adult: 1.4 by 0.6 mm. large ventral sucker is situated to the right of the midline

two oval testes: unequal in size, arranged obliquely side by side and situated in the posterior third of the body

ovary: globuse, situated at the junction of the middle and lower third of the body

Morphology:Haplorchis taichu

Adult: large ventral sucker a globuse ovary only one testis

EGGS light yellow brown ovoidal, operculated smallest trematode egg: 20 – 30 by 15 – 17 micra Shell:

o slight shoulder at the rim of the operculum

o knob at the posterior pole maybe occasionally observed

fully developed miracidium already present within the egg when it is deposited by the adult worm

LIFECYCLE: eggs are passed out into the environment with the feces Eggs ingested by 1st IH: fresh water snail

o The first intermediate host of the species of Heterophyds

are: H. heteophyes:

Pironella conica Cerithidia cingula

M. yokogawai : Semisulcospira, Thiara and Hua

H. taichu Melania juncea, Thiara riquetti

Inside the 1st IH: eggs à sporocyst à one or two generations of rediae à cercaria

Cercaria, that emerge from the snails and penetrate 2nd IH: a suitable fish species

The second intermediate hosts are: H. heterophyes: Mugil, Salmo, Acanthogobius M. yokogawai : Plecoglossus, Salmo, Richarsonium,

Odontobutis

H. taichu: Ambassis burensis (langaray) Amphacathus jacus (samaral) Anabas testidineus (martiniko) Arius manilensis (kanduli) Claris batrachus (hito) Gerris kapas (malakapas)

o Glossogonius giurus (bia)

o Hemiramphus georgii (cansusuit or bugning)

o Ophiocephalus striatus (dalag)

o Pelates quarilineatus (babansi)

o Therapon plumbeus (ayungin)

Metacercaria:o encyst on or under the scales, in muscles, fins tails or gills

of the second intermediate hosto Man ingests metacercaria:

raw or insufficiently cooked infected fish is ingested by the definitive host

metacercaria escapes from the cyst à adult worm (1week) and attaches itself to the intestinal wall

Pathogenesis: inflammation at the site of attachment causing damage to the intestinal mucosa = mucoid diarrhea

colicky pain: severe abdominal pain caused by spasm, obstruction or distention of any hollow viscera (ex. Intestines)

adult worm: may burrow deep into the intestinal wall = become trapped

and eventually die eggs of the degenerating worms:

blood stream and lymphatics: carried to the different parts of the body

heart muscles: cardiac failure resembling that of cardiac beri-beri

brain: fatal cerebral hemorrhage spinal cord: loss of motor and sensory functions at the

levels where the lesions are located Diagnosis: identification of eggs/ova in stool

Treatment: Praziquantel & Tetrachloroethylene