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January 08, 2006
CHAGAS' DISEASE In rural Latin America Chaga's Disease has infected between 16 to 18 million people. It has also infiltrated the urban area due to migration. Hikers, campers, missionaries, archeologists, anthropologists and travelers should possess some knowledge of the disease and how to avoid it. In 1909 Dr. Carlos Chagas was studying Malaria in Brazil and found a parasite in the blood of a child with enlarged lymph nodes and a fever. He had identified this parasite in an insect two years previously. Dr. Chagas believed the parasite was passed by the saliva of the infected vectors of the parasite carrying insect. In 1912 this was proved wrong. It was actually the feces of the insect feeding on human blood that passed the parasite to the victim. The Vinchuca is the insect that carries the parasite. It is oval shaped, brown in color and is about two centimeters long. It has two pairs of wings but has limited flight range. Both the male and the female require blood of vertebrates for survival. It prefers the face and usually will feed for about twenty minutes. The Vinchuca lifts the proboscis and flexes the distal segment upwards. It then releases a stylet with teeth that perforates the skin. A second stylet then taps a blood vessel. During the feeding defecation transpires which passes the passes the parasite into the wound. The sleeping victim will usually rub the bite which introduces the organism into the blood. The parasite can enter through the cells covering the mucosa of the mouth and nostrils.
A hard violet hued swelling usually appears at the bite location after about a week. This is a reaction to the parasites. White blood cells surround the clusters of parasites and destroys both fat cells and the parasite. However, some parasites enter the blood system and invade the heart, brain, liver, and spleen. An acute form of Chagas' Disease develops in about two percent of the victims. Young children are extremely susceptible. Symptoms include: fever, rash, anorexia, diarrhea, vomiting, swollen lymph nodes, and an enlarged liver. In adults the acute infection usually manifests itself by an enlarged heart. The white blood cells will surround the infected fibers and try to swallow the parasites. The lesions can decrease the contractility of the heart. It reduces the heart output which leads to heart failure. In most cases the symptoms subside within a 4-8 week period and the victim continues to live an apparent normal life. Most victims don't suffer immediate acute illness. Many will not display any manifestations because the infection is slight. The infection may be unrecognized for decades until a serological test is performed. The infection may gradually progress with resultant heart disease. The infected heart muscle fibers are replaced by scar tissue. This will thin the walls of the heart. The heart operations can be so severely affected that irreversible heart failure may occur. The central nervous systems and peripheral nervous system may also be irreversibly damanged. Benzimidazole and Nifurtimox have been successful in destroying the parasites in the acute phase of the illness. Improved housing is imperative to any long term plan to control disease. Also, destruction of the insects carrying the parasite would help considerably in the eradication of Chagas' Disease. DDT has not been successful. Diedrin has worked, fumigant canisters and insecticidal paints have had some impact on the spread of the disease. There are no drugs to prevent the infection. Rules for Preventing Chagas' Disease During Your Travels 1. Don't sleep in native's hut. The parasite-carrying Vinchucas harbor in the palm-frond roofs and in the cracks of walls. 2. If you are staying in older or budget hotels be sure to check for hidden insects under mattresses, behind pictures, drawers and any dark areas (i.e. closets). Be sure to have insect repellent with you. Any commercial product with DEET is suitable. 3. Use pyrethrin insecticides to kill insects which may be present. Spray under your bed and in all cracks. 4. If you have to handle insects be sure to cover your hands with gloves or a cloth. 5. Use bed nets. Place a cloth over the net to keep feces of the insects from falling through the net. 6. In choosing a campsite stay away from palm trees as well as stone or wood piles. 7. If you are in need of a blood transfusion avoid private hospitals. There is a minimal or no risk of being infected in University or Public hospitals in a major city where the blood has been screened. In Argentina, Brazil, Honduras, Uruguay and Venezuela blood bank screening is mandatory. 8. Suggested Links About Chagas - Kiss of Death , Chagas Disease
By Nicholas Crowder The above information has been provided by the International Association for Medical Assistance to Travelers. Originally published July/August 1996 in Latin America Traveler ISSN 10960-4878 Copyright 1998 by Crowder Publications
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