TREMATODES(Flukes)

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:

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

generally yellow brown or brown colored

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

Life Cycle - Complex

= requiring one or more intermediate host

Classification of Trematodes:I. Species which inhabit the small intestine

a)Fasciolopsis buski b)Echinostoma ilocanum c) Echinostoma malayanumd)Heterophyse heterophysee)Metagonimus yokogawai

II. Specie that inhabit the lung a)Paragonimus westermani

III. Specie that inhabit the livera)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

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

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

Ova hen’s egg shape (identical to that of F. hepatica) thin-shell with small operculum at one end unembryonated when laid

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

Diagnosis: Demonstration of egg in stool

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

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

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. ilocanum1st 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

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: 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 wormo 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 bodyo ovary lobed located post. to the ventral sucker o vitellaria extensively branched and covers the entire

length of the bodyo cirrus and cirrus pouch absent o uterus tightly coiled into a rosette found near the VS

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

Ova cercaria

Disease: Paragonimiasis/Endemic Hemoptysiso acquired through ingestion of raw or undercooked crab

meat containing encysted metacercariao clinical manif.: nausea, sweating, chronic cough with

bloody sputum, dyspnea and pleuritic chest paino human are definitive host o pulmonary infection is easily mistaken for pulmonary TBo 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