Parasitology
Lab-15 (Echinococcus granulosus)
1- Echinococcus granulosus:
1- It is the smallest tape warm can infect the human ( 8-9mm or 1cm length)
2- definitive host : dog and other canidae
3- intermediate host : human , sheep ,goats , swine and others
4- habitat : adult worm in the small intestine of dog (definitive host)
5- infective stage to man : egg in the feces of infected dog
6- infective stage to dog : larval or cystic stages in sheep
7- life cycle
غير هام
((The adult Echinococcus granulosus inhabit the upper part of
small intestine of the definitive hosts, dogs or other canids( cats, foxes and wolves).
Gravid proglottids release eggs that are passed in the feces as a diognostic stage for
infected dogs These eggs are infective stage to a suitable intermediate host (sheep,
goat, cattle and man). After ingestion, the eggs hatches in small intestine and
releases an oncospher (emberyo) that penetrates the intestinal wall and migrates
through the circulatory system into various organs, especially the liver and lungs. In
these organs, the oncosphere develops into a hydatid cyst that enlarges gradually,
producing protoscolicis incide the cyst. The dogs ( definitive host )and other canids
becomes infected by ingesting the H. cyst-containing organs of the infected
intermediate host. After ingestion, the scolex evaginate, attach to the intestinal
mucosa, and develop into adult stages in 30 to 80 days. ))
8- human is dead end of the cycle
9- oncosphere cause diseases in the human 70% in liver – 20% in lung – 10% other
organs – when reach the C.N.S it may lead to death
10- The disease called ( Hydatid disease (hydatidosis) ): Is caused by the larval stages
(hydatid cyst) ----> very common disease in Iraq ,Turkey, Syria and in country with
sheep
11- This disease called belong to SOL (space occupying lesions ) this mean that the
development of disease depend on the organ which contain the hydatid cyst . and it
differ from organ to another ( the parasite has no toxin )
12- Trauma and surgery lead to rapture of hydatid cyst inflammation and
hypersensitivity death of the patient
13- Diagnosis :
1. History of patients in endemic areas.
2. X-ray picture, detection of the cyst mass in organ.
3. Ultrasound scan - MRI - CT scan.
4. Biopsy not recommended before operation, but is essential to confirm
the diagnosis after surgical operation.
5. Serology tests (IHA- ELISA- PCR- Casoni skin test)
14- Treatment : surgical removal after 2 months of albendazole for shrinkage of cyst
15- morphology :
1— adult :
1
- head : contain scolex (piriform shape)+ 4 suckers + two rows of hooks +
rostellum (used to attach to intestinal mucosa )
2- Immature segment : small + not contain any differentiated organs
3- Mature segment : contain fully developed male and female sexual organs
4-Gravid segment : contain only uterus full with eggs.( 10-15 uterine branches)
2— hydatid cyst : ( size = 1cm and it may reach 50 cm )
1- Germinal layer: inner thin layer + cuboidal cells + it is primary layer of the
parasite + continuously produce protoscolecis .
2- Hyaline layer: non-nucleated + used to maintain the shape of hydatid cyst .
3- Fibrous tissue layer: thick + formed as a result of the defense mechanism in the
body against the hydatid cyst .
4- Outer host- tissue capsule: derived from the tissue that contain the hydatid cyst.
5- The sac : contain protoscolexs ( invagenated scolecs called hydatid sand )
3— egg :
1- Spherical
2- 35-45um in diameter .
3- Hexacanth Embryo centrally located .
4- Radially staited shell