Trematodes

TREMATODES (Flukes)

Life Cycle - Complex = requiring one or more intermediate host

General Charac.: All flukes: leaf-like in appearance - Except Schistosomes generally Hermaphroditic (posses both male and female genitalia) - Except Schistosomes ♦ cross-fertilization and self-insemination are method of reproduction provided with oral and ventral suckers Except Schistosomes ; some flukes have genital sucker (Gonotyl) MOT • oral ingestion of the infective stage: encysted metacercaria, Except - Schistosomes • requires 2 I.H. - Except Schistosomes • egg operculated - Except Schistosomes • terribly difficult to get rid of once infected, may accumulate for 10-20 years Morphology & Structures: ( Adult worm) • flattened, leaf-shaped, unsegmented worms • body covered with non-cellular integuments which may be smooth or spiny • musculature consist of outer circular, middle oblique and an inner longitudinal integuments (serves to alter the shaped of the worm) • possess 2 cup-shaped muscular suckers bearing spines or hooklets surrounding the mouth ♦ oral sucker (found anteriorly surrounding the mouth) used for ingestion and procurement of food ♦ ventral sucker/ acetabulum - found posteriorly in the ventral surface (for attachment) • oral cavity leads to the muscular esophagus from which the intestine branches to form 2 intestinal ceca which runs parallel to each other ending near the posterior end (figure of an inverted ) • no body cavity, most of the rest of the body is taken up by reproductive organ and some associated structure • lack circulatory system • excretory system - bilaterally symmetrical and opens at posterior end of body • nervous system - composed of paired lateral ganglia in the region of pharynx which are directed to nerve trunk • series of glandular structure (vetilaria) lying lateral to the intestinal ceca Egg: • •

Adult worm (sm. intestine of vertebrate host) ↓ lays egg ↓ excreted in water and hatch ingested by human ↓ ↑ miracidium liberated metacercaria ↓ ↑ enter 1st I.H. (snail) enters & encyst in tissue of 2nd I.H. (fish, water vegetation) (intramolluscan phase) ↑ sporocyst → redia 1 → redia 2 → cercaria → swim

Classification of Trematodes: I. Species which inhabit the small intestine a) Fasciolopsis buski b) Echinostoma ilocanum c) Echinostoma malayanum d) Heterophyse heterophyse e) Metagonimus yokogawai II. Specie that inhabit the lung a) Paragonimus westermani III. Specie that inhabit the liver a) Clonorchis sinensis b) Opisthorchis felineus c) Opisthorchis vinerrini d) Fasciola hepatica e) Fasciola gigantica f) Eurytrema pancreaticum IV. Species which inhabit the portal blood circulation a) Schistosoma japonicum b) Schistosoma hematobium c) Schistosoma mansoni Intestinal Flukes

smooth, hard shell and operculated or with lid at one end except (Schistosomes non-operculated) generally yellow brown or brown colored

Fasciolopsis buski (Giant Intestinal Fluke) • common intestinal parasite of human and pigs in the Orient • lives in the small intestine of its definitive host rather than in the liver Disease: Fasciolopsiasis Geographical Distribution: Central and South China, Taiwan, Vietnam, Thailand, Indonesia and other parts of Orient Morphology: Adult worm: • live attached to the bowel wall primarily in the duodenum and jejunum

• • • • • • • • Ova • • •

elongate, broadly ovoidal, large and fleshy anterior end narrower than posterior end integument – spinose absence cephalic cone or shoulder ventral sucker larger than oral sucker located close to it dendritic testes at the posterior half of the body in tanderm ovary branched and lies midline anterior to the testes vitelaria extensive at the lateral site to the caudal end hen’s egg shape (identical to that of F. hepatica) thin-shell with small operculum at one end unembryonated when laid

Treatment: Hexylresorcinol/Tetrachlor Ethylene/Praziquantel 30mg/kg body weight Echinostoma ilocanum (Garrison’s fluke) Geog. Distribution: • Confirmed to be endemic in the Philippines • Prevalent in Northern Luzon, Leyte, Samar and Mindanao • also found in Indonesia, India, China, Thailand, Japan, Malaysia and Sumatra Disease: Echinostomiasis Morphology: Adult worm: • elongated, bluntly rounded • integument covered with plaque-like scales • anterior end rounded and provided with circumoral disc • oral sucker lies in the center of circumoral disc surrounded with collarette of spines (distinguishing characteristic) • ventral sucker in the anterior fifth of the body • 2 deeply lobed dumbell-shaped testes arranged in tandem at the posterior half of the body • vitellaria at the lateral side of the body Ova • •

ovoidal and operculated immature when passed in feces

Life Cycle: = involves 2 snail intermediate host

MOT: ingestion of metacercaria encysted on fresh water vegetation (bamboo shoots or water chestnuts) which may be consumed raw or peeled w/ the teeth Pathogenesis and Clinical infection: • pathological changes caused by the worm are traumatic, obstructive and toxic to the intestinal mucosa • there is localized inflammation, ulceration, abscesses formation and hemorrhages at the sites of worm attachment • diarrhea, abdominal pain, anorexia, nausea and vomiting may occur • malabsorption syndrome and impairment of Vit B12 absorption occur in some infected patient

Pathogenesis and Clinical manif: • adult worm attaches to the wall of the small intestine producing inflammatory reaction leading to diarrhea • light infection usually asymptomatic • heavy infection can result to mild ulceration of the intestinal mucosa producing bloody diarrhea and abdominal pain • absorption of the metabolites of the worm may result in general intoxication • clinical manif.: abdominal colic, episodes of diarrhea, restlessness and pruritus Diagnosis: Demonstration of charac. ova in stool Treatment: Tetrachlorethylene/Praziquantel/Hexylresorcinol

Diagnosis:

Demonstration of egg in stool

Prevention: Through cooking of the snail that serves as the second intermediate host of the parasite

Echinostoma malayanum Geographical distribution: = Malay Peninsula, India, China, Sumatra Morphology: Adult • ovoid and bluntly rounded • oral suckers surrounded with spines • testes – deeply indented at tandem • excretory system – Y- shape appearance and pouch-like excretory bladder Ova: yellow to yellowish brown

L. C.: = Same as E. ilocanum 1st I.H. (snail) Lymnae Lueleola 2nd I.H. (snail) Indoplanorbis Pathology and Symptomatology: Same as E. ilocanum Diagnosis: Finding ova in the stool Treatment and Prevention:

Same as E. ilocanum

Metagonimus yokogawai (Yokogawai fluke) Disease:

Metagonimiasis

Geographical distribution: • Spain, Israel, USSR, Prevalent in the Far East Morphology: Adult worm: • pyriform-shape, broadly rounded posteriorly and pointed anteriorly • size somewhat larger than heterophyes • ventral sucker deflected to the right • vitellaria in a fan-shaped distribution • 2 oval unequal size testes at posterior-third of the body Ova • • •

minute, ovoidal and operculated absence of knob at abopercular end fully embryonated when laid

Cercaria • tail keeled, armed with spines • pigmented eyespots

Pathology and Clinical Feature: • causes mild inflammatory reaction in the intestine • ectopic ova can cause granuloma in other organ especially in the liver and brain Lab. Diagnosis: Finding ova in the stool Treatment: = Tetrachlorethylene & Praziquantel Bithionol & Niclosamide – have been shown to decrease egg production Prevention: • Avoid eating raw or inadequately cooked fish • Domestic animal should be prevented from eating fish offal Heterophyes heterophyes = smallest of the fluke but the deadliest Disease: Heterophyiasis Geographical distribution: • Egypt, Turkey,

•

Prevalent in the Far East (Japan, Korea, Central & South) China, Taiwan & Philippines

Morphology: Adult worm: • oval or pyriform-shaped, pointed anteriorly, rounded post. • integument covered with scale-like spines more numerous near the anterior end • 2 ovoid-shaped testes at the posterior fifth of the body • seminal receptacle retort shaped • cirrus and cirrus sac absent • provided with 3 suckers: ♦ ventral sucker – larger and thick-walled than oral sucker ♦ genital sucker (gonotyl) – found posterior to the ventral sucker (not present in Metagonimus) ♦ oral – smaller compared to ventral sucker ova • • •

ovoid-shaped, operculated embryonated when oviposited fully developed miracidium present within the egg when deposited by adult worm

cercaria tail keeled with arm spines pigmented eyespots

Ova: broadly ovoidal, thick-shelled with flattened prominent operculum measures 80 X 55u unembryonated when laid Cercaria: ellipsoidal body with minute oral stylet knob-shaped tail with spine oral sucker larger than ventral sucker

Pathogenesis: • mild local inflammatory reaction at site of attachment causing damage to intestinal mucosa • chronic intermittent diarrhea, nausea, colicky abd. pain • eggs of degenerating flukes are spilled into blood stream and disseminate to different parts of the body ♦ heart - provokes tissue reaction leading to cardiac failure ♦ spinal cord - result in loss of motor and sensory function at the level where lesions are located ♦ brain – fatal cerebral hemorrhage Diagnosis:

cercaria

Ova

Recovery of eggs in stool

Treatment: Tetrachlorethylene & Praziquantel Bithionol & Niclosamide – have been shown to decrease egg production Prevention ♦ Avoid eating raw or inadequately cooked fish ♦ Domestic animal should be prevented from eating fish offal ♦ Thorough cooking kills the parasite Lung Fluke Paragonimus westermani (Oriental Lung fluke) = most widely prevalent specie Geog. Distribution: o Endemic in Asia and India o In U.S. occur in immigrants from these areas Morphology: Adult worm o thick, fleshy, reddish-brown or coffee-bean color in living specimen anteriorly rounded and tapering posteriorly o integuments covered with scale-like spines o oral and ventral suckers are about equal in size o 2 deeply lobed testes arranged side by side at the posterior - third of the body o ovary lobed located post. to the ventral sucker o vitellaria extensively branched and covers the entire length of the body o cirrus and cirrus pouch absent o uterus tightly coiled into a rosette found near the VS

Disease: Paragonimiasis/Endemic Hemoptysis o acquired through ingestion of raw or undercooked crab meat containing encysted metacercaria o clinical manif.: nausea, sweating, chronic cough with bloody sputum, dyspnea and pleuritic chest pain o human are definitive host o pulmonary infection is easily mistaken for pulmonary TB o invasion stage of the disease may cause few or no symptoms o once in the lung, worm stimulate inflammatory response which enshrouds granulation of the lung capsule which later ulcerate and heal slowly o egg deposition may produce more pronounced tissue reaction Lab. Diagnosis: Finding the typical operculated egg in sputum, pleural fluids and feces Treatment:

Praziquantel, Bithionol (alternate drug)

Prevention: o Adequate cooking of crabs/crayfish before eating o Proper disposal of human waste