Chagas' Disease

(American Trypanosomiasis)

Chagas' disease is a parasitic infection endemic in many rural areas of Latin America. Between 16 - 18 million persons are infected in the countrysides of all Latin American countries, including Mexico, and migration of rural populations to the cities is bringing the disease to urban areas, the result of blood transfusions and organ transplants. Chagas' disease is a threat to international travelers as well.

Cause

Chagas' disease is an infection caused by a protozoal parasite transmitted by contact with the feces of the vinchuca (also known as cone nose, assassin bug, kissing bug, or reduviid bug), which transmits the parasite through its bite. The vinchuca is about 2 centimeters long, with an oval-shaped, brownish-colored body and a long, narrow cone-shaped head. It breeds and lives in palm trees. The insect is transported to dwellings in palm fronds to be used as roofing, and hides among the palm fronds and in the cracks of the mud or adobe walls of the thatched houses. The vinchuca depends on blood for survival. It comes out to feed at night, attracted to the exposed parts of the body, especially the face. During its feeding, it contaminates the wound with its feces, introducing the parasite which causes the disease.

Signs and symptoms

Following a bite, usually on the skin of the eyelid or on the conjunctiva, a hard, violet-hued swelling called a "chagoma" appears after one week. Eventually the parasites reach the heart, liver, brain, or spleen, causing an acute form of the disease in about two percent of patients, especially small children, resulting in fever, a generalized rash, anorexia, diarrhea, vomiting, swollen lymph nodes, and an enlarged liver. Meningoencephalitis can occur and may cause death in children.

In adults, an acute infection of the heart is the main result, damaging the heart muscle. Most of the victims of Chagas' disease survive the acute heart infection, the symptoms subside within four to eight weeks, and the person continues to live an apparently healthy life. The disease however progresses and goes on unrecognized, remaining undiagnosed until a routine blood test may disclose it. The disease finally surfaces after 10 to 20 years in the form of chronic heart disease, as the infected heart muscle fibers are slowly replaced by scar tissue, thinning the walls of the heart, severely affecting heart function, and ultimately resulting in death. The nervous system may also be affected causing convulsions, paralysis, and brain damage.

Treatment

If Chagas' disease is recognized in its early stages, drug treatment may clear the patient of parasites. However, in chronic cases, once the disease has damaged the heart, brain, and other organs, only the symptoms of the disease can be managed. At present, no drugs are available to prevent the infection, and there are no vaccines.

Risk

Hikers and campers are particularly vulnerable to Chagas' disease, as are people working in rural areas. Even those travelers spending the night in the suburbs or peripheries of cities ought at minimum to check for insects in bedrooms. International travelers passing through endemic areas may become infected, but may remain apparently healthy until the first signs of infection appear years later as chronic heart disease.

Prevention

1) When traveling in endemic areas, do not sleep in natives' hut, since parasite-carrying vinchucas shelter in the palm-frond roofs and in the cracks of walls.

2) When checking into modest or older hotels, search for hidden insects under the mattress, behind pictures, in drawers, or dark corners of the room. Carry repellents and insecticides with you.

3) Before bed apply insect repellent to exposed parts of your body (available in sprays, lotions and towelettes), which may help to keep the insects away. Any commercial preparation containing DEET (N, N-diethyl-meta toluamide) is suitable.

4) Use pyrethrin insecticides to kill insects which may be present in your sleeping quarters. Spray the walls around your bed, especially where there are cracks. Spray under your bed, inside closets, drawers and behind pictures.

5) Protect your hands with a cloth, paper, plastic or gloves if it is necessary to handle the insects.

6) Use bednets to prevent contact with insects. Put a cloth over the bednet to prevent infected feces falling on you from the ceiling.

7) When choosing a campsite, stay away from palm trees, and do not set your tent close to stone or wood piles, where insects may be hiding.

8) If you require medical or surgical treatment involving blood transfusions, avoid private hospitals where blood donors may not have been adequately screened; there is no risk of becoming infected this way at a university or civic hospitals in a major cities. In Argentina, Brazil, Honduras, Uruguay and Venezuela blood bank screening of blood is compulsory by law.

Diseases