Chagas' disease, or American Trypanosomiasis, is considered the most important cause of heart disease in Latin America. The disease is named for Carlos Chagas, a Brazilian scientist who described it in 1907 and subsequently described the vector and parasite.

Chagas' disease is common from Argentina to Mexico. A few cases are seen, in Texas and California.

Transmission Cycle
Chagas' is caused by a flagellated protozoan, Trypanosonia cruzi. It is transmitted by triatomine, or "kissing" bugs, through blood transfusions, and from mother to child during pregnancy.

More than 150 wild mammals are reservoirs of the infection. Armadillos, raccoons, opossums and rodents are major reservoirs. As wild animals disappear from the environment, dogs, cats, guinea pigs, goats, house rats and other domestic animals replace them as reservoirs.

Symptoms
The infection occurs in three phases: acute, latent and chronic.  The acute stage is often asymptomatic or presents mild symptoms, but may cause death in young children. A latent phase with no apparent symptoms may last for years.
27 percent of those infected may develop the chronic stage. It can cause circulatory problems, damage to the central nervous system and the heart muscle, and enlargement of the digestive track (megaesophaous or mevacolon). Sudden death by acute cardiac arrest is common.

Economic Impact
A study in Brasilia found that one in 10 deaths in a group aged 25-65 had heart disease directly associated with Chagas'.  A loss of 21,2175 working years per 100,000 males and 1,363/ 100,000 females was estimated.
In Brazil, where about 4 percent of the population has antibodies demonstrating previous exposure to T. cruzi, annual productivity losses due to Chagas' are estimated at $250 million. As additional $5 billion a year is lost because of absenteeism.

Child Survival
The acute phase of Chagas' is more severe in children than adults and can cause death in those younger than two. Studies in Bolivia found that 8 percent of newborns with seropositive mothers suffered from congenital Chagas' and 13 percent of acute cases in children developed into chagastic meningitis.

Environmental Health
Chagas' disease is associated with poverty and poor housing in rural areas. Vectors live in wall cracks, thatch roofs and adjacent animal shelters. Socioeconomic advancement is probably as important for control as medicine and vector control.

Humans make contact with the sylvatic T. cruzi cycle when they invade the habitats of wild vectors and reservoirs. As these areas are settled and become dominated by humans, wild reservoirs are forced out and people and domestic animals become a stable source of blood for some of the vectors. Construction of houses and outbuildings provides a dark, humid, protected environment for the vectors.

Chagas' Control
Serological surveys have shown that vector control through housing improvement and spraying houses and outbuildings with insecticides can halt transmission and ultimately reduce Chagas' cases.
House modification and insecticide application will not be successful or sustainable unless people understand and value their importance. Effective community-level education programs about Chagas' disease control and prevention are needed to support vector control.

USAID and the government of Bolivia have begun a three-year pilot program to test community-based Chagas' control strategies under the country's child survival project. The program uses a combination of housing improvement, health education and vector control to combat Chagas'.

Treatment
Early diagnosis is essential because Chagas' is untreatable during the chronic phase. Two drugs, nifurtimox and benznidazole, are effective against the acute phase. Both drugs produce serious gastrointestinal and neurological side effects and treatment requires medical supervision.

Blood Transfusions
infection through transfusion and contamination of blood bank supplies is a growing problem in Latin America. Blood can be cleared of T. cruzi in 24 hours with a diluted solution of gentian violet, but most countries have inadequate facilities for screening and holding infected blood.

Studies report contaminated blood levels of 5-50 percent in certain regions. Sale of blood by people migrating to cities from infected areas is a major concern.

Transmission through transfusion could be prevented by providing blood screening and blood banks, most likely in association with HIV screening.