Transcript Document 7483171

parasitology
• Medical Parasites:
• - Protozoa
• - Helminthes:
• - Arthropoda
•
•
1- Platyhelminthes
2- Nemathelminthes
3- Nematomorpha
4- Acanthocephala
5- Annelida
Classification of Helminthes
According to transmission methods
• 1- Soil transmitted Helminthes : Ascaris, Hook worms
• 2- Snail t. H. : Trematoda( Schistosoma,….)
• 3- Arthropods t. H. : Fillaria, Dracanculus medinensis
• 4- Food and Meat t. H. : Taenia saginata, Taenia solium
• 5- Direct t. H. ( contagious H.): Enterobius vermicularis,…
Trematoda (Flukes)
• Morphology:
• Biology
• General characters:
•
•
•
•
- size
- digestive tract
- reproductive system
- excretory system
• Life cycle
F: Fasciolidae
• Genus:
The trematodes;
• Fasciola hepatica (the sheep liver fluke)
• Fasciola gigantica ,parasites of herbivores that
can infect humans accidentally .
Fasciola hepatica
• Morphology:
• -size: adult fluk measures 2030 x 13mm wide and is flat
and leaflike, with a spiny
tegument.
Adult form of Fasciola hepatica
Egg of Fasciola
•The egg is large, 130-150 µm x 60-90 µm, Color is yellow to light brown
•.Unembryonated, filled with yolk cells in which an indistinct germinal cell is
embedded.
Life cycle
Geographic Distribution
Fascioliasis occurs worldwide.
Human infections with F. hepatica are found in areas
where sheep and cattle are raised,
and where humans consume raw watercress, including
Europe, the Middle East, and Asia.
Infections with F. gigantica have been reported, more
rarely, in Asia, Africa, and Hawaii
‫پاتوژنزیس‬
‫مکانیسم باتوژنز‪:‬‬
‫• تورم ‪,‬نکروزو فیبروز کبدی و آتروفی پارانشیم کبدی‬
‫• هیپرپالزی‪,‬آدنوماتوز و فیبروز و انسداد مجاری صفراوی ناشی از‬
‫متابولیتهای سمی کرم وتحریکات مکانیکی کرمهای بالغ‬
Clinical Features
During the acute phase
manifestations include; abdominal pain, hepatomegaly,
fever, vomiting, diarrhea, urticaria and eosinophilia,
and can last for months.
In the chronic phase:
the symptoms are more discrete and reflect intermittent
biliary obstruction and inflammation.
Ectopic locations of infection
‫يافته‌‌هاي‌باليني‌بيماران‌مبتال‌به‌فاسيوليازيس‌در‌كرمانشاه •‬
‫•‬
‫ـ شكايات بيماران مبتال به فاسيوليازيس در كرمانشاه•‬
Laboratory Diagnosis
• In chronic phase:
• Microscopic identification of eggs in the stools or in
material obtained by duodenal or biliary drainage.
• They are morphologically indistinguishable from those
of Fasciolopsis buski .
*False fascioliasis (pseudofascioliasis)
*Antibody detection tests are useful especially in the early
invasive stages, when the eggs are not yet apparent in the
stools, or in ectopic fascioliasis .
Antibody Detection
The current tests of choice for immunodiagnosis of
human Fasciola hepatica infection are enzyme
immunoassays (EIA) with excretory-secretory (ES)
antigens combined with confirmation of positives by
immunoblot.
Antibody levels decrease to normal 6 to 12 months
after chemotherapeutic cure and can be used to
predict the success of therapy .
‫تشخیص‬
‫تشخيص‌پاراکلينيک‪:‬‬
‫• انجام‌سی‌تی‌اسکن‌( ‪) CTS‬‬
‫• سونوگرافی‌کبد‬
‫تشخيص‌يارازتيولوژيک‪:‬‬
‫• آزمايش‌مدفوع‌و‌جستجوی‌تخم‌انگل‌در‌فاسيولوزيس‌مزمن‬
‫• توباژ‌دوازدهه‌و‌جستجوی‌تخم‌در‌ترشحات‌دوازدهه‬
‫تشخيص‌سرولوژيک‪:‬‬
‫• تستهای‌‪( ELISA, IFA‬با‌حساسيت‌‪ %75/96‬و‌ويژگی‌‪) %77/96‬‬
‫• ‪ ( C.C.I.E‬جهت‌بررسی‌رو‌ند‌درمان)‬
Treatment
Unlike infections with other flukes ,
Fasciola hepatica infections may not
respond to praziquantel.
The drug of choice is triclabendazole with
bithionol as an alternative .
‫تخم کرم‬
‫کرم بالغ در کبد‬
‫کرم بالغ‬
F.hepatica, adult worm, liver biopsy
Laboratory diagnosis
Fasciola hepatica: although direct diagnosis by observation of eggs in faecal smears
it the reference method, indirect diagnostic tests such as IF may allow diagnosis
when direct observation is negative.
Immunodiagnosis by indirect immunofluorescence.
Antigen: frozen sections of Fasciola hepatica.
Dicrocoelium dendriticum
( D. lanceolatum)
• Life cycle of D. lanceolatum
Schistosoma
General character:
Morphology
Reproduction
system(dioecious)
Importance
Morphology
Size:
- Female 12 to 26 mm
- Male 6 to 22 mm
At least seven species are parasites of
Humans.
The three main species infecting
humans are:
Schistosoma haematobium,
Sch. japonicum ,
and Sch. mansoni .
gynaecophoric canal
testes
Adult an larve of Sch.
Schistosomulum
Geographic Distribution
• It has been estimated that about 220 million people
are infected in the world.
Schistosoma mansoni is found in parts of South
America and the Caribbean, Africa, and the Middle
East ;
Sch. haematobium in Africa and the Middle East;
• and Sch. japonicum in the Far East .
Current Status of Schistomiasis in
IRAN
• Schistosoma haematobium was found in Khuzestan
Province, but its prevalence is declining because of
large scale control activities.
• A total of 2400 B. truncatus snails were randomly
collected from southern and eastern districts of the
Dezful region were examined for schistosome
cercariae. Not a single Schistosoma cercaria was
obtained from the snails.
Life Cycle
Miracidium & Cercaria
Liver worm
Clinical Features
• Many infections are asymptomatic.
• Swimmer’s itch ( Cercarial Dermatitis)
• Acute schistosomiasis (Katayama's fever) may occur weeks after
the initial infection, especially by S. mansoni and S. japonicum.
The earliest bladder lesion is the pseudotubercle, but in longstanding infections nests of calcified ova (‘sandy patches)
• Occasionally central nervous system lesions occur.
Schistosoma eggs
reaction to Zeihl-nelsen staining
• JK
Sch. mansoni egg
Sch. haematobium egg
Sch. japonicum egg
Epidemiology of Schistomiasis
Cercarial Dermatitis
Immuno-pathologic consequences
• Granulomatous reactions and fibrosis in the affected organs, which
may result in manifestations that include:
• colonic polyposis with bloody diarrhea (Schistosoma mansoni
mostly);
• portal hypertension with hematemesis and splenomegaly (S.
mansoni ,S. japonicum,)
• cystitis and ureteritis (S. haematobium) with hematuria, which can
progress to bladder cancer;
•
pulmonary hypertension (S. mansoni ,S. japonicum ,more rarely S.
haematobium) ;glomerulonephritis; and central nervous system
lesions
Hepatomegaly & splenomegaly
Granuloma
( Sch. japonicum egg)
• The international agency for research on cancer
(IARC) considers S. haematobium infection a
definitive cause of urinary bladder cancer with an
associated 5-fold risk.
Epidemiological analyses have been conducted in
China and Japan and support a role of S. japonicum
infection as one of the risk factors for”hepatocellular
carcinoma and/or colorectal cancer”, along with
others, such as hepatitis virus (HBV& HCV)
infection and alcoholic intake.
Laboratory Diagnosis
• Microscopic identification of eggs in stool or urine is the most
practical method for diagnosis.
•
• Stool examination should be performed when infection with
S. mansoni or S. japonicum is suspected,
•
and urine examination should be performed if S.
haematobium is suspected.
Tissue biopsy (rectal biopsy and biopsy of the bladder) may
demonstrate eggs when stool or urine examinations are
negative .
Antibody detection
•
Antibody detection can be useful to indicate
schistosome infection in patients who have
traveled in schistosomiasis endemic areas and
in whom eggs cannot be demonstrated in fecal
or urine specimens .
Treatment
• Safe and effective drugs are available for the treatment
of schistosomiasis.
• The drug of choice is praziquantel for infections caused
by all Schistosoma species.
• Oxamniquine has been effective in treating infections
caused by S. mansoni in some areas in which
praziquantel is less effective .