Download - 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 hepaticaCharacteristics
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Fasciola hepaticaCharacteristics
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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