AMERICAN TRYPANOSOMIASIS-CHAGAS DISEASE.pptx

Medical Microbiology.

1. AMERICAN TRYPANOSOMIASIS-CHAGAS DISEASE FRANCOIS SHIMOLI BULIMU HSM 201-OO43/2020

2. Epidemiology It is a zoonotic disease limited to south and central A merica. Carlos Chagas , investigating malaria in 1909, accidentally found this trypanosome in the intestine of a triatomine bug and then in the blood of a monkey bitten by the infected bugs. He named the parasite Trypanosoma cruzi after his mentor Oswald Cruzi , and the disease named after him.

3. Epidemiology… It is endemic to rural areas of central and south A merica, closely linked to the habitat of it’s vector. The vector thrives in these regions especially, those with poor housing conditions where they can easily infest homes and feed on human blood.

4. Vector Reduviid bugs are important in human transmission. Also called kissing bug since it bites people around the mouth or eyes. They include: Triatoma infestans , Rhodnius prolixus and Panstrongylus megistus . They feed at night and defecate while feeding.

5. Triatomine bug

6. Transmission Reservoir host: Armadillo, cat, dog, pigs and man. Transmitted when mucus membranes, conjunctiva or wound on the surface of skin is contaminated by feces of bug containing metacyclic trypomastigote . Other modes include: blood transfusion, organ transplant and vertical transplant.

7. Life Cycle

8. Life Cycle

9. Life Cycle Definitive host- human. Intermediate host- Reduviid bug. Vector stage Triatomine bug takes bloodmeal from infected man. It ingests trypomastigote forms of the parasite. Trypomastigote transforms into epimastigote in the midgut .

10. Life Cycle Epimastigote multiplies and differentiates into metacyclic trypomastigote which migrates to the hindgut. Human stage During a blood meal, infected triatomine bug defecates and release metcyclic trypomastigote . It enters human body through scratching bite site.

11. Life Cycle They penetrate macrophages and muscle cells. Intracellularly , they transform into replicative amastigote form which multiplies by binary fission forming a pseudocyst . Rupture of infected cells and the pseudocyst leads to release of tryomastigote forms which circulate in blood.

12. Pathogenesis The parasite is transmitted to man first. In acute phase, parasites circulate in blood as they replicate rapidly. There is dissemination to various tissues such as heart and gastro intestinal tract.

13. Pathogenesis In chronic phase, parasites persists in tissues and cause organ damage. In heart muscle, cardiomyopathy causes arrhythmias and heart failure. Damage to the nerves of the gastrointestinal tract leads to megacolon and mega esophagus.

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