Nasty Infectious Diseases You Want To Avoid - Chagas Disease
Chagas disease is a parasitic disease also known as American trypanosomiasis transmitted by the bite of blood-sucking insects and rarely by blood transfusions. Named for 19th-century Brazilian physician Carlos Chagas, the disease is endemic in Central and South America, where it is recognized as a serious public health problem. Officials there rank their need to control this disease third, behind malaria and schistosomiasis.
More than a quarter of the total population in Central and South America are at risk, with more than a million cases each year. Of these, 45,000 people will die and up to 18 million people may be currently infected. Of these, 3 million may have already developed chronic complications, and more than 3 million are still in the incubation period. The disease is also known as Brazilian trypanosomiasis, Chagas-Cruz disease, Cruz trypanosomiasis, and South American trypanosomiasis.
Trypanosoma cruzi is primarily found in the United States in a variety of woodland wildlife, including armadillos, squirrels, opossums, raccoons, woodrats and mice. Of these, opossums are particularly significant as disease reservoirs because the parasite has the ability to complete its life cycle in the anal glands of the opossum without having to resort to the insect vector. Up to 37.5% of all opossums in the United States may be infected.
Cause - The disease is caused by the singlecelled parasite Trypanosoma cruzi, very similar to those that cause sleeping sickness in Africa. The parasite infects bugs commonly known as "assassin bugs" or "cone-nosed bugs" (reduviid); when the bugs defecate, the excrement includes the parasite, which can then enter a human through a break in the skin or through a mucous membrane. The parasites live in the bloodstream and can also affect a person's heart, intestines, or nervous system.
Symptoms - The disease may occur in an acute or chronic form. The acute form (common in children, rare in adults) is marked by a lesion at the site of infection, together with fever, weakness, enlarged spleen and lymph nodes, facial and leg swelling, and rapid heartbeat. This form disappears on its own in about four months, unless complications (such as encephalitis) set in. About 10 to 20 years after the initial acute phase, incurable lesions of the disease develop. In addition, 27 percent of those infected develop a chronic heart disease problem. Six percent have chronic lesions in the digestive tract, and about 3 percent may have neurological problems. Patients with chronic disease become progressively sick and ultimately die, usually as a result of heart failure.
Treatment - Nifurtimox is available from the CDC for the treatment of short-term Chagas disease. There is no accepted anti-parasitic treatment for chronic illness.
Prevention - The best prevention is to avoid potential reduviid habitats (mud, adobe, and thatch buildings, especially those with cracks or crevices). If this isn't feasible, infection may be prevented by spraying infested areas with insecticide, using fumigant canisters and insecticidal paints, and using bed nets. Housing improvements have also helped. In addition, screening blood donors at blood banks helps to control the spread of the disease via blood transfusions. In 1991, the health ministers of Argentina, Bolivia, Brazil, Chile, Paraguay, and Uruguay began a program to eliminate Chagas disease by the end of this century. Since then, house infestation has declined 75 to 98 percent in some areas, according to the Pan American Health Organization.