taenia solium and taenia saginata

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  • 1. Taenia saginata/ Taenia solium

2. Restate the basic concepts of parasitology Define of the various terms related to basic parasitology Discuss briefly the life cycle and pathogenesis of medically important parasites Apply the knowledge of the life cycle to the principles of laboratory diagnosis Learning outcomes: 3. What is parasitology? Parasitology is the study of parasites, their hosts, and the relationship between them. What is medical parasitology? Medical parasitology is the subject which deals with the parasites that infect humans, the diseases caused by them, clinical picture and the response generated by humans against them. It is also concerned with the various methods of their diagnosis, treatment and finally their prevention and control. 4. 1. Morphology - important in laboratory diagnosis which helps to identify the different stages of development. 2. Geographical distribution Easy escape of the parasite from the host Environmental conditions favoring survival outside the body of the host The presence of an appropriate vector or intermediate host Basic Concepts of Parasitology 5. Common phase Route a parasite follows inside the body Route a parasite follows outside the body 3. Life cycle of a parasite Symptoms, pathology and diagnosis Epidemiology, prevention and control 6. 4. Host parasite relationship Carrier state - a perfect host parasite relationship where tissue destruction by a parasite is balanced with the hosts tissue repair. Disease state - this is due to an imperfect host parasite relationship where the parasite dominates the upper hand. Parasite destruction occurs when the host takes the upper hand. 7. 5. Laboratory diagnosis Blood malaria Stool Amoebiasis Urine urinary Schistosomiasis Sputum amoebic abscess of lung or in the case of amoebic liver abscess bursting into the lungs, the trophozoites of E. histolytica are detected in the sputum. Biopsy material - spleen punctures in cases of kala-azar, muscle biopsy in cases of Cysticercosis, and Chagas disease. Urethral or vaginal discharge for Trichomonas vaginalis 8. 6.Prevention and control Reduction of the source of infection Good personal hygiene Sanitary control of drinking water and food Proper waste disposal Avoidance of unprotected sexual practices 9. Any organism that depends on another organism, i.e. the host, for food, shelter, or some other benefit and which receives these benefits in such a way that the host experiences detrimental effects as a consequence. The parasites included in medical parasitology are protozoa, helminthes and some arthropods. Parasite 10. Ectoparasite a parasitic organism that lives on the outer surface of its host e.g. lice, ticks, mites etc. Endoparasite parasites that live inside the body of their host e.g. Entamoeba histolytica Obligate parasite This parasite is completely dependent on the host during a segment or all of its life cycle e.g. Plasmodium spp. 11. Facultative parasite an organism that exhibits both parasitic and non-parasitic modes of living and hence does not absolutely depend on the parasitic way of life, but is capable of adapting to it if placed on a host E.g. Naegleria fowleri Erratic parasite is one that wanders in to an organ in which it is not usually found E.g. Entamoeba histolytica in the liver or lung of humans. 12. Definitive host a host that harbors a parasite in the adult stage or where the parasite undergoes a sexual method of reproduction. Intermediate host - harbors the larval stages of the parasite or an asexual cycle of development takes place. In some cases, larval development is completed in two different intermediate hosts, referred to as first and second intermediate hosts. 13. Oncosphere- the larva of the tapeworm contained within the external embryonic envelope and armed with six hooks Scolex- the attachment organ of a tapeworm , generally considered the anterior or cephalic end Proglottids- one of the segments making up the body of a tapeworm Extrinsic incubation period-The interval between the acquisition of an infectious agent by a vector and the vector's ability to transmit the agent to other susceptible vertebrate hosts. 14. Taenia saginata is a beef tapeworm. Taenia solium is a pork tapeworm. Taenia saginata and Taenia solium 15. 16. 17. Taeniasis is the infection of humans with the adult tapeworm of Taenia saginata or Taenia solium. Humans are the only definitive hosts for T. saginata and T. solium. Eggs or gravid proglottids are passed with feces ; the eggs can survive for days to months in the environment. Cattle (T. saginata) and pigs (T. solium) become infected by ingesting vegetation contaminated with eggs or gravid proglottids . In the animal's intestine, the oncospheres hatch , invade the intestinal wall, and migrate to the striated muscles, where they develop into cysticerci. A cysticercus can survive for several years in the animal. 18. Humans become infected by ingesting raw or undercooked infected meat . In the human intestine, the cysticercus develops over 2 months into an adult tapeworm, which can survive for years. The adult tapeworms attach to the small intestine by their scolex and reside in the small intestine . Length of adult worms is usually 5 m or less for T. saginata (however it may reach up to 25 m) and 2 to 7 m for T. solium. 19. The adults produce proglottids which mature, become gravid, detach from the tapeworm, and migrate to the anus or are passed in the stool (approximately 6 per day). T. saginata adults usually have 1,000 to 2,000 proglottids, while T. solium adults have an average of 1,000 proglottids. The eggs contained in the gravid proglottids are released after the proglottids are passed with the feces. T. saginata may produce up to 100,000 and T. solium may produce 50,000 eggs per proglottid respectively. 20. Taeniasis Passage of proglottids in stool Mild irritation at site of attachment Epigastric pain Weakness Weight loss Loss of appetite Pruritis Obstruction in intestine ,bile duct and appendix because proglottids are actively motile Taenia saginata Pathogenesis 21. Mild ,non-specific abdominal complaints Proglottids are not as motile as T.saginata so organ obstruction is less likely Cysticercus cellulosae involving any organ or tissues(common subcutaneous tissues and muscle) Autoinfection by finger contamination with eggs from perianal skin or faeces Neurocysticercosis- Cysticercosis of the brain Taenia solium Pathogenesis 22. Taeniasis Confirmative diagnosis of taeniasis is made by finding gravid proglottides or egg in stool Direct fecal smear Brine floatation technique Cellophane-tape technique Visualization of Taenia eggs-has poor sensitivity and difficult to differentiate from T.saginata Coproantigen detection ELISA-95% sensitivity and 99% specificity Cysticercosis Biopsy of subcutaneous nodules, X-ray, CT scan or MRI are used for the diagnosis of brain type and ophthalmoscope examination is used for ocular form Immunological test are for reference only Diagnosis 23. Treatment for cysticercosis Surgical removal is required for ocular and superficial cysticercosis Praziquantal may be used to treat brain cysticercosis but it should be taken in a hospital Prevention Health education Avoid eating raw pork Avoid pigs eating human stool Sanitary inspection of slaughter and sanitary disposal of night soil 24. 25. Thanks

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