Trypanosoma Cruzi
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Contents |
Epidemiology
- United States, Central & South America rarely, cases orginate in United States
- transmitted by kissing bugs of the family Reduviidae, so named because it often bites the face
- bug defecates at the time of biting
- bug feces contain infective trypomastigotes that penetrate the skin as a result of scratching or rubbing or through intact mucosa
- infection may be transmitted by blood transfusion
- vertical transmission from mother to baby
- dogs, rodents, armadillos, & other domestic & wild animals serve as reservoirs
Pathology
- after gaining access to tissues, typomastigotes transform into dividing amastigotes
- when the infected cell is full of amastigotes, transformation to trypomastigotes occurs, followed by cell rupture
- trypomastigotes are released into the peripheral blood where they reach distant tissues & begin the replicative cycle again
- cross-reactivity of Trypanosoma cruzi antigens with human protein(s) <see serology>
Clinical-manifestations
- may cause acute or chronic infection
- acute infection:
- generally lasts 2-3 months
- fever/ chills, malaise, hepatosplenomegaly, myocarditis
- swelling of the tissue around the eye may be present if bite occurred on face ( Romana's sign)
- swelling of the tissues around the bite at other sites is called a chagoma
- acute disease is more common in children under 5
- in older individuals, infection is generally mild or asymptomatic
- the patient remains infected for life
- megaesophagus
- megacolon
- autoimmune destruction of parasympathetic innervation of heart
- quiescent infections may be exacerbated by immunosuppression
Laboratory
- diagnosis is made by demonstration of trypomastigotes in blood, buffy coat or aspirates of lymph nodes or chagomas
- trypomastigotes
- curved with S & C shapes
- measure up to 20 um in length
- kinetoplast larger than that of T brucei
- examination of the gut contents of laboratory-raised rejuviid bugs that have been allowed to feed on the victim
- EIA, IFA & ELISA are available
- false positives may occur in patients with Leishmaniasis
- antibodies against TCFL5 ( nuclear antigen)
Complications
- occur in 30% of infected individuals
- heart failure, 45% within 10 years of onset
- arrhythmia, including sudden death
- dysphagia from esophageal dilation
- reactivation of dormant disease in immunosuppressed patients
Management
- treatment is unsatisfactory
- nifurtimox
- markedly reduces duration of symptoms, parasitemia & mortality
- 50% of infections are cured by a full course of therapy
- may be useful in exposure from laboratory accidents
- treatment should be begun as soon as possible
- 8-10 mg/kg/day for adults
- 12.5-15 mg/kg/day for adolescents
- 15-20 mg/kg/day for children ages 1-10 years
- doses given orally, divided QID
- therapy should be continued to 90-120 days
- available from CDC (707 639-3670)
- 5 mg/kg/day PO for 60 days
- delays progression to heart failure (10% vs 45&) [4]
- (Not available in USA)
- referral to cardiologist for cardiac involvement
- referral to gastroenterologist for GI manifestations
- no vaccine available
More General Terms
References
- Clinical Diagnosis & Management by Laboratory Methods, 19th edition, J.B. Henry (ed), W.B. Saunders Co., Philadelphia, PA. 1996, pg 1266
- Stedman's Medical Dictionary 26th ed, Williams & Wilkins, Baltimore, 1995
- Harrison's Principles of Internal Medicine, 14th ed. Fauci et al (eds), McGraw-Hill Inc. NY, 1998, 1193-94
- Viotti R, Vigliano C, Lococo B, Bertocchi G, Petti M, Alvarez MG, Postan M, Armenti A. Long-term cardiac outcomes of treating chronic Chagas disease with benznidazole versus no treatment: a nonrandomized trial. Ann Intern Med. 2006 May 16;144(10):724-34. PMID: [1]
- Pinto Dias JC. The treatment of Chagas disease (South American trypanosomiasis). Ann Intern Med. 2006 May 16;144(10):772-4. No abstract available. PMID: [2] - Chagas Disease [3]
- Centers for Disease Control and Prevention [4] Division of Parasitic diseases (physicians) 770-488-7775
