Schistosomiasis & Fascioliosis

7/28/2019 Schistosomiasis & Fascioliosis

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Schistosomiasis

Parasitology Dept.


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Human Blood Flukes

Schistosomatidae Three main species that infect man:

Schistosoma japonicum(Africa, Middle East, India)

Schistosoma mansoni(Africa, Middle East, SuthernAmerica)

Schistosoma haematobium(China, Japan, SEA)

Indonesia : Schistosoma japonicum

Four minor species that infect man: Schistosoma mekongi Schistosoma intercalatum

Schistosoma bovis

Schistosoma matthei


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Human Blood Flukes

Schistosomatidae Sexually dimorphic

Male has gynaecophoric canal

Egg is not operculated Requires only one intermediate host (snail)

Forked-tail cercaria (infective stage)

Do not have encysted metacercaria Portal of entry: skin penetration

Adults do not multiply


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SchistosomatidaeGeneral Characteristics

Blood flukes Anterior part contains 2 suckers Requires 1 intermediate host (aquatic

snail) Egg has no operculum

Sexually dimorphic, male and femalelive together (male has gynae-cophoric canal)

Bifurcated tail cercaria (infectivestage)

Do not have encysted metacercaria Portal of entry: skin penetration Adults do not multiply


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SchistosomatidaeGeneral Characteristics


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Schistosoma japonicumGeneral

Distributed in Far East Asia e.g. Japan,China, Thailand, Philippine, Malaysia andIndonesia

Causes schistosomiasis japonica, Katayama

disease Sexually dimorphic

Habitat is superior mesenteric vein andbranches of final host

Final host is humans

Reservoir hosts are other mammals

Intermediate host is Onchomelania spp. snail


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Schistosoma japonicumMorphology

Egg is short ovoidand not operculated,

has lateral knob, andcontains miracidium

Bifucated tail cercaria


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Schistosoma japonicumMorphology

Male:

About 15 mm long and broader thanthe female, the body rolled ventrally to

form a groove, canalis gynecophorus,into which the female worm fits

There are about 6-8 testes on the

dorsal side behind the ventral sucker Smooth body surface


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Schistosoma japonicumLife Cycle

Eggs in the feces o/t final host hatches i/twatermiracidium

Miracidium invades the Onchomelaniasporocyst rediae cercaria

Cercaria comes out o/t snail and infects afinal host by adhering to the body surfacew/ its suckers and penetrating the skin

They move to the portal vein superiormesenteric vein and develop into adults


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Schistosomiasis

Parasitology Dept.


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Transmission

Caused by person passing feces or urine(depending on species) containing eggs

into water which is used for bathing,washing clothes, fishing and agricultural,and recreational purposes

The egg which contains a fully-formedmiracidium hatches out when the egg isimmersed in water


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Transmission

The miracidium swims actively topenetrate an appropriate snail host and

develop to become cercariae, the infectivestage for man

The cercariae emerge from the snail

mainly on exposure to light and infectman by penetrating the skin


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Transmission

Caused by person passing feces or urine(depending on species) containing eggs

into water which is used for bathing,washing clothes, fishing and agricultural,and recreational purposes

The egg which contains a fully-formedmiracidium hatches out when the egg isimmersed in water


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Transmission

The tail of cercariae is shed duringpenetration and the parasite transformedinto schistosomula inside the host tissues

It enters the systemic circulation and thenfinds its way into the portal circulation

Snail hosts : Genus Onchomelania - S. japonicum Genus Biomphalaria - S. mansoni

Genus Bulinus - S. haematobium


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Habitat

Schistosoma japonicumand Schistosomamansoni mature in the mecenteric veins

o/t portal circulation

Schistosoma haematobium generally

remains in the systemic circulation andmature in the blood vessels of the uretricand vesical plexus


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1. Cercariae invade skin,casting off its tail

2. Enter the vein

3. It is carried to the heart

4. Passes through the lung andreturns to the heart

5. Via mesenteric artery itreaches the intestinal wall

6. It moves from capillaries tovenous branches

7. Finally inhabits the portalvein

8. Some cercariae in the lung

penetrate diaphragm andinvade the liver

9. Enter the portal vein

10. Mature adults release ova tooutside by destruction o/t

host intestinal mucosa


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Clinical Aspects

Invasive stage:

Pruritic rash appear

on parts o/t bodywhich have contactwith watercontaining cercariae

Develops after 24after exposure andmay last for 2-3 days

Eosinofilia


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Clinical Aspects

Acute stage:

Katayama fever: severe immune reaction to

the products of young flukes and eggs, occurswithin 5-10 wks after infection

It takes a form of an acute illness with fever,malaise, weakness, weight loss, muscular andabdominal pain, vomiting, lymhadenopathy,hepatic and spleen enlargement


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Clinical Aspects

Chronic stage:

In S. japonicumand S. mansoniinfection,gastrointestinal involvement appear first diarrhea,

abdominal pain and headache due to production ofeggs

Formation of granulomata (colonic and rectal polyps),ulceration, thickening of bowel wall as well as portal

vesselsclay pipe-stem fibrosis (Symmers fibrosis) As more eggs enter portal circulation, portal

hypertension developliver and spleen enlargement,anemia, ascites, rupture of varicose veins,hemathemesis , melena death


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Clinical Aspects

Schistosomiasis mansoni:multiple strictures withmultiple polyps and muchaltered mucosal pattern


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Clinical Aspects

Human liver showingpipe-stem fibrosis(Symmers fibrosis)


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Intestinal lession inschistosomiasis japonica

1. Adults in portal vein2. Migrate into small vessels and

lay eggs3. Both mechanical stimulus and

toxin from eggs rupture thevessel, eggs then entersurrounding tissue to causecellular infiltration, papillomaformation and

4. Ulceration o/t intestine. Eggsappear in the intestinal cavityand are egested outside w/bloody diarrhea

5. Eggs deposited in externalwall, stay there for long time

and make a nodule6. Mesenteric toxin of eggs7. lymph nodes become swollen

due to bacterial infection


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Clinical Aspects

In S. haematobiuminfection:

the most common symptom is

hematuria/proteinuria Inflammatory reaction and granuloma

formation in the bladder is also common

Calcified eggs causing damage to urinary tract Ureter becomes obstructed


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Clinical Aspects

Eggs that are sweptalong with the flowof blood into iliacvein and enter thesystemic circulationcan appear in anytissue to form

granuloma, fibrosis,eg. lung lession,brain

Pulmonary schistosomiasis


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Diagnosis

Parasitological diagnosis by finding eggs infeces or urin

Biopsy o/t rectum to find eggs bycolonoscopy

Immunodiagnostic test: ELISA

Radiology: calcification in bladder

USG: pipe-stem fibrosis


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Treatment

Praziquantel (drug of choice): highefficacy, low toxixity, short treatment

course, kills the worm therefore help toreduce/stop egg production

S. mansoni: single oral dose 40 mg/kg

S. haematobium: single oral dose 40 mg/kg


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Treatment

Schistosoma japonicum:

Chronic stage: total dosage 60 mg/kg

(children 70 mg/kg) in 2-3 divided dosesduring 1 day or 6 divided doses over 2 days

Acute stage: total dose of 120 mg/kg(children 140 mg/kg) given over 4-6 days


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Human Liver fluke

- Fasciola hepatica

- Fasciola gigantica

- Opistorchis viverrini- Clonorchis sinensis

Main species :

Fasciola hepatica & Fasciola gigantica: widelydistributed in Asia.


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Fasciola hepaticaGeneral

Family Fasciolidae

Distributed entirely over Europe, southeastern

Africa, America continents, Oceania, and Japan Final host: originally ruminants, occasionally

humans

Required 2 intermediate host; 1st is fresh watersnail (Lymnaea spp.), 2nd is water plants


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Fasciola hepaticaCharacteristics

Adult: flat and leaf-like, 2-3 cm in length, 1cm in width, cephalic cone structure in the

anterior end

Complicated-branched intestine

Branched testis, branched ovary, coiled

uterus Vitelline gland has complicated branches,

spread all over the lateral body


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Fasciola hepaticaEggs

Egg is largestamong those of

Trematodes Eggshell is thin,

light yellow,operculated

Contains eggcell


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Fasciola giganticaGeneral

Family Fasciolidae

Distributed in Africa, southeast Asia,Hawai, India, Pakistan

Life cycle resembles that ofF.

hepatica


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Fasciola giganticaCharacteristics

Adult: large, thin,and long

Cephalic cone is notvery obvious

The internalstructure is similar to

the previous one Egg is similar to

other Fasciolidae


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Fasciola giganticaCharacteristics

Life cycle


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Life cycle


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Clinical Aspects

Fever, chill

Epigastrial pain

Icteric

Mild to severe diarrhea

Prognosis : good,exceptfor severe infection

Severe infection :billiary duct :chronic fibrosis


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Diagnosis

Parasitological diagnosis by finding

eggs / adult worms in feces Sometimes adult can be found in

vomites

Treatment

bithionol 0.03 gr for 18 days

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Schistosomiasis & Fascioliosis