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Trematode (fluke, distoma)
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- Named after Dr. Carlos Chagas, a Brazilian doctor who first described the disease in 1909
Pathogen
Morphology
- amastigote
- promastigote
- epimastigote
- trypomastigote
- nucleus, kintoplast, undulating membrane, flagellum
Life cycle
- T. brucei group don't infect human cells
- T. cruzi needs to infect human cells to multiply
- Armadillo is natural reservoir
Transmission
by Triatomine
- Transmitted by oral ingestion or mucosal infestation of feces of Triatomine, so-called 'kissing bugs'
- Triatomine
- Inhabits gaps on mud-built walls
- Sucks human blood but no blood transmission occurs
- Active during night
by Mother-to-child
Epidemiology
- In 21 Latin American countries
- 700,000 new cases in 1990
- 38,000 new cases in 2010
- Estimated 10,000 deaths/year by Chagas disease
Clinical course
- Acute phase
- Mainly asymptomatic
- local swelling at the site of inoculation (Chagoma)
- fever, anorexia, lymphadenopathy, mild hepatosplenomegaly, myocarditis
- trypomastigote found in blood for 8-12 weeks after infection
- children <5y/o fatal 10% in acute phase
- Chronic phase
- 20-30% of infection
- 10-40 years after infection
- cardiomegaly, arrhythmia, heart failure
- trypomastigotes invade and destruct cardiac muscle cells
- EKG shows typically right bundle branch block
- dilation of esophagus, megacolon - dysphagia and constipation
- trypomastigotes invade and destruct intestinal smooth muscle cells
Diagnosis
- blood smear, with blood centrifugation
- molecular
- serology
- clinical diagnosis
Treatment=
- acute phase
- nifurtimox
- benznidazole (nitroimidazole)
- both contraindicated for pregnant women, kidney failure, liver failure
- chronic phase
- no specific treatment targeted pathogens
- supportive therapy for each organ dysfunction
prevention and control
- vector control
- improvement of house constructions
- insecticide
- mass screening