How do African and American trypanosomiasis differ?

African trypanosomiasis (sleeping sickness) is caused by Trypanosoma brucei spread by tsetse flies and progresses to fatal central-nervous-system disease, whereas American trypanosomiasis (Chagas disease) is caused by Trypanosoma cruzi spread mainly by triatomine bugs and causes chronic heart and digestive disease (brun-2010; rassi-2010).

Why is Chagas disease often diagnosed years after infection?

The acute phase of Chagas disease is frequently mild or unnoticed, and the chronic cardiac and digestive complications can emerge years to decades later, so many people are recognized only in the chronic phase (rassi-2010; perez-molina-2018).

Trypanosomiasis

Trypanosomiasis is disease caused by flagellate protozoa of the genus Trypanosoma. Two clinically distinct forms affect humans: human African trypanosomiasis (sleeping sickness), caused by Trypanosoma brucei subspecies and transmitted by tsetse flies, and American trypanosomiasis (Chagas disease), caused by Trypanosoma cruzi and transmitted mainly by triatomine bugs. Both are neglected tropical diseases with substantial chronic morbidity.

Definition

Trypanosomiasis is infection by protozoan parasites of the genus Trypanosoma — Trypanosoma brucei causing African sleeping sickness and Trypanosoma cruzi causing American Chagas disease — transmitted by insect vectors and producing distinct neurological or cardiac and gastrointestinal disease.

Scope

This entry covers the two human trypanosomiases together: their causative species and vectors, the staged course of African sleeping sickness, the acute and chronic phases of Chagas disease, and their geographic separation between sub-Saharan Africa and the Americas. It is a reference topic within parasitic and tropical infectious disease and cross-links the protozoal-infections overview. It is not clinical or prescribing guidance.

Key concepts

Trypanosoma brucei and Trypanosoma cruzi
Tsetse fly and triatomine bug vectors
Human African trypanosomiasis (sleeping sickness)
Haemolymphatic and meningoencephalitic stages
Chagas disease acute and chronic phases
Chagasic cardiomyopathy and megasyndromes
Antigenic variation

Mechanisms

In human African trypanosomiasis, Trypanosoma brucei parasites injected by a tsetse fly multiply in blood and lymph (the haemolymphatic stage) and later cross into the central nervous system (the meningoencephalitic stage), producing the sleep-cycle disturbance that gives sleeping sickness its name; the parasite evades immunity by continually switching its surface coat through antigenic variation (brun-2010). In Chagas disease, Trypanosoma cruzi is transmitted mainly when triatomine-bug faeces contaminate the bite site or mucosa, and also through blood, congenitally, or by ingestion; after an often mild acute phase, parasites persist in tissue and, in a proportion of people, drive chronic chagasic cardiomyopathy and digestive megasyndromes years to decades later (rassi-2010; perez-molina-2018).

Clinical relevance

Untreated human African trypanosomiasis is generally fatal once the central nervous system is involved, and chronic Chagas disease is a leading infectious cause of cardiomyopathy in endemic regions. Both are tracked as neglected tropical diseases with active control and elimination programs (brun-2010; rassi-2010; hotez-2007). This entry characterizes the diseases for orientation and evidence appraisal and is not a basis for individual diagnosis or treatment.

Epidemiology

Human African trypanosomiasis is confined to tsetse-fly belts of sub-Saharan Africa and has declined markedly under sustained control, approaching elimination targets in some areas (brun-2010). Chagas disease is endemic across Latin America, where millions are chronically infected, and has spread to non-endemic regions through migration; vector control and screening of blood and organ donation have reduced transmission (rassi-2010; perez-molina-2018; hotez-2007).

Evidence & guidelines

Knowledge and programs rest on World Health Organization guidance for the control and treatment of human African trypanosomiasis and Chagas disease and on disease-specific reviews; the references here are orienting reviews rather than treatment protocols (brun-2010; perez-molina-2018).

History

Sleeping sickness was a devastating epidemic disease of colonial-era Africa, and the elucidation of Trypanosoma brucei and its tsetse-fly transmission in the early twentieth century founded much of tropical parasitology. Carlos Chagas described the American disease that bears his name in 1909, identifying the parasite, vector, and clinical syndrome — an unusually complete single-author discovery. Twentieth- and twenty-first-century control through vector reduction, surveillance, and treatment has reshaped the epidemiology of both forms (brun-2010; rassi-2010).

Key figures

Reto Brun
François Chappuis
Anis Rassi
José Antonio Marin-Neto
José A. Pérez-Molina

Seminal works

brun-2010
rassi-2010
perez-molina-2018

Frequently asked questions

How do African and American trypanosomiasis differ?: African trypanosomiasis (sleeping sickness) is caused by Trypanosoma brucei spread by tsetse flies and progresses to fatal central-nervous-system disease, whereas American trypanosomiasis (Chagas disease) is caused by Trypanosoma cruzi spread mainly by triatomine bugs and causes chronic heart and digestive disease (brun-2010; rassi-2010).
Why is Chagas disease often diagnosed years after infection?: The acute phase of Chagas disease is frequently mild or unnoticed, and the chronic cardiac and digestive complications can emerge years to decades later, so many people are recognized only in the chronic phase (rassi-2010; perez-molina-2018).