Chagas Disease

The world health organization (WHO) describes Chagas disease as below. Visit their web site to learn more. www.who.int/ctd/chagas/

Chagas disease has a wide distribution in Central and South America, being found only in the American Hemisphere. It is endemic in 21 countries, with 16-18 million persons infected and 100 million people at risk. The disease is caused by Trypanosoma cruzi, a flagellated protozoan parasite which is transmitted to humans in two ways, either by a blood-sucking reduviid bug which deposits its infective feces on the skin at the time of biting, or directly by transfusion of infected blood. Humans and a large number of species of domestic and wild animals constitute the reservoir, and the vector bugs infest poor housing and thatched roofs.

The acute stage of the disease is generally seen in children, and is characterized by fever, swelling of lymph glands, enlargement of the liver and spleen, or local inflammation at the site of infection. But, commonly, there are no acute clinical manifestations, and those infected may remain without symptoms. In about one-third of acute cases, a chronic form develops some 10-20 years later, causing irreversible damage to the heart, oesophagus and colon, with dilatation and disorders of nerve conduction of these organs. Patients with severe chronic disease become progressively more ill and ultimately die, usually from heart failure. There is, at present, no effective treatment for such cases.

Rural migrations to urban areas during the 1970s and 1980s changed the traditional epidemiological pattern of Chagas disease: it became an urban disease, as unscreened blood transfusion created a second way of transmission. Between 1960 and 1989, the prevalence of infected blood in blood banks in selected cities of South America ranged from 1.7% in Sao Paulo, Brazil to 53.0% in Santa Cruz, Bolivia, a percentage far higher than that of hepatitis or HIV infection.

Currently, there is a continued decreasing trend in the prevalence of house infestation by the vector bug (Triatoma infestans) and the incidence of human infection in children and youngsters,in the countries of the Initiative of the Southern Cone.

Image from:  www.who.int/ctd/chagas/geo.htm