Parasites Affecting GIT - Cestodes 2 PDF

Faculty of Medicine GIT Module Parasitology lecture Parasites affecting GIT Cestodes 2  - Identify the characteristic morphology of Dipylidium caninum, Echinococcus granulosus and Echinococcus multilocularis. - Classify Dipylidi...

Faculty of Medicine GIT Module Parasitology lecture Parasites affecting GIT Cestodes 2  - Identify the characteristic morphology of Dipylidium caninum, Echinococcus granulosus and Echinococcus multilocularis. - Classify Dipylidium caninum, Echinococcus granulosus and Echinococcus multilocularis according to their taxonomic morphological and biological features. - Identify the geographical distribution of Dipylidium caninum, Echinococcus granulosus and Echinococcus multilocularis. - Illustrate the life cycle of Dipylidium caninum, Echinococcus granulosus and Echinococcus multilocularis. - Discuss the pathology and manifestations of Dipylidium caninum, Echinococcus granulosus and Echinococcus multilocularis infection. - Select the appropriate method/s that should be used for the diagnosis and prevention of Dipylidium caninum, Echinococcus granulosus and Echinococcus multilocularis infection.  - Dipylidium caninum - Echinococcus granulosus - Echinococcus multilocularis.  Dipylidium Caninum Disease: Dipylidiasis, dog tapeworm infection. Geographical distribution: Adult worm Cosmopolitan.  Morphology Adult: Size 20-60cm in length and has about 60- 175 proglottids. Scolex: 4sucker, retractile rostellum with 1- 7 rows of hooks The mature segment: cucumber-seed like and contains two sets of genital organs. - The Gravid segment: contains uterus divided into packets (egg capsules).  Egg: Each egg capsule contains 5-15 eggs. The egg is spherical, 40m in size and contains mature oncosphere. Egg capsule Cysticercoid: a bladder like structure, the head is withdrawn in upright position. there is no tail appendage attached  Life cycle Habitat: The lumen of the small intestine. Definitive host: Dogs, cats, wild carnivores, and accidentally human. Intermediate host: Larval stages of dogs, cats and human fleas. Infective stage: Cysticercoid. Mode of infection: Ingestion of cysticercoid in infected flea.  Pathology: The pathological lesions are related to the worm burden. There may be intestinal irritation and eosinophilia.  Clinical picture - Light infection is usually asymptomatic, - abdominal pain, - diarrhea and - pruritus may occur in some individuals.  Diagnosis Finding characteristic proglottids or eggs capsule in the feces.  Treatment Praziquantel or niclosamide.  Prevention 1. Children should not touch dogs and cats infested with fleas. 2. House hold pets should be given anthelmintic and insecticidal treatments. 3. Treatment of patients  Echinococcus granulosus Disease: - Hydatid disease in intermediate hosts - Echinococcosis in definitive host. Geographical distribution: Cosmopolitan.  Adult stage Size: 0.5 cm Scolex: globular with 4 suckers and double crown of hooks similar to taenia solium. Strobila: formed of immature, mature and gravid. Mature segment: longer than broad similar to Taenia. Gravid segment: longer than broad, uterus has lateral bouches.  Egg: Like Taenia egg. - yellowish-brown, - 30x40m, - has thick radially striated shell - contains mature hexacanth embryo (onchosphere).  Hydatid cyst: -The larval form of E. granulosus Size: 1-10cm Shape: - Spherical- shaped - unilocular - 2 layers: - outer laminated ( non cellular) - - inner germinal (cellular) secrets the laminated layer, scolices, brood capsule and daughter cyst contains : hydatid fluid. - hydatid sand - scxolices - brood capsule - daughter cyst - exogenous daughter cyst -  Morphology of Hydatid Cyst Fibrous layer Diagnostic Stage Laminated layer Germinal layer Exogenous Hydatid sand daughter cyst Daughter cyst Hydatid fluid Individual scolices Brood capsules E. granulosus Life cycle  Life cycle Habitat: Adult inhabits the small intestine of dogs, Definitive host: Dogs, and other carnivores (fox, wolves). Intermediate host: Man (occasionaly), sheep, Cattle, camels, horses and other herbivores. Infective stage: The eggs. Mode of infection: Human is infected via: ingestion of eggs in water or vegetables Handling infected dogs as hair contaminated with eggs  Pathologyand clinical picture Pathology depend on size and site of the cyst: The liver is the most common site of the hydatid cyst (66%). Followed by the lungs (25%) and, less frequently, the spleen, kidneys, heart, bones and brain. The slowly growing cyst is often well tolerated until it reaches 10 cm in diameter. The cyst causes impairment of the affected organs due to pressure and erosion of blood vessels. The neighboring tissue cells undergo atrophy and pressure necrosis.  Sudden release of cystic fluid can precipitate an anaphylactic shock that ranges in severity from mild to lethal, and the associated dissemination of scolexes can result in multiple hydatid cyst formation.  Diagnosis 1- Clinical picture and history of residence in endemic area and close association with dogs. 2-Radiologicalexaminations : x-ray, ultrasound CTscaning 3-Eosinophilia is present in less than 25% of patients 4-Serologic tests: Intact cysts produce a low level of antigenic stimulation. and nearly 5 to 10% of intact liver cysts and nearly 50% of intact lung cysts can be serologically negative.  Treatment 1-Surgical: If cyst is single cyst or few, In an accessible location, it should be enucleated. 2- PAIR technique: when the cyst is large or infected: Puncture of the cyst wall, Aspiration of cyst contents, Instillation of 2% silver nitrate to kill scolices and Re- aspiration of the scolicidal agent. 3. Albendazole + praziquantel: - inoperable cases - prophylaxis before and after surgery  Echinococcus multilocularis This parasite is very similar to E. granulosus with some differences: Disease: Alveolar hydatid disease. Geographic distribution: North America, northern and central Europe and Asia.  Morphology There is no laminated layer, hense the cyst has no regular shape. The germinal layer infiltrates the tissue. In man the cyst is usually sterile (absence of protoscolices).  Life cycle Habitat: small intestine of foxes, wolves and other carnivores. Definitive host: foxes, wolves and other carnivores.. Intermediate host: rodents, small mammals and occasionally human Infective stage: The eggs. Mode of infection: via ingestion of eggs.  Pathology: Liver is the primary localization of E. multilocularis larvae in human. Local extension of the lesion and metastases to the lungs and brain can follow. The larval mass proliferates by budding of the germinal layer, producing an alveolar like pattern of microvesicles. The progressive invasion of the surrounding tissues resembles cancer in behavior and appearance.  Diagnosis Serologic tests  Treatment 1- surgical treatment 2- Medical treatment: Mebendazole- Albendazole  A male patient 20 years old presents at the physician complaining of abdominal pain and abdominal swelling. With history of close association with dogs. Clinical examination revealed a palpable mass in the right upper quadrant of the abdomen. Ultrasonography confirmed a fluid-filled cyst in the right lobe of the liver, elevated liver function tests were observed. Blood picture revealed eosinophilia. 1- What is the diagnosis? 2- What is the infective stage? 3- What is the mode of infection?  The progressive invasion of the surrounding tissues resembles cancer in behavior and appearance may present in: a. E. granulosus b. E. multilocularis c. D. caninum d. T. solium Stray dogs should be eradicated for control of infection with : a. T. solium b. T. saginata c. E. granaulosus d. D. latum The patient may be infected with Dipylidium caninum through a.Ingestion of cysticercus bovis in infected flea b.Ingestion of cysticercus cellulose in infected flea c.Ingestion of cysticercoid in infected flea d.Ingestion of e g g in infected flea