Thursday, May 31, 2012

Scientists: Chagas disease is the ‘new HIV/AIDS’

By David Ferguson -

Chagas disease, or American trypanosomiasis, is set to be “the new HIV/AIDS of the Americas” according to a paper in the Public Library of Science (PLoS) journal “Neglected Tropical Diseases.” The New York Times cited the article Tuesday, saying that the social and economic impact of Chagas disease, which is a close relative of African trypanosomiasis, more commonly known as sleeping sickness, will be just as devastating in coming years as HIV/AIDS has been to Africa.
The paper’s authors, a group composed largely of faculty from Houston’s Baylor College of Medicine, argue that the spread of Chagas (which is named for the Brazilian physician who discovered it, Dr. Carlos Chagas) through Latin and Central America mirrors the early spread of HIV in several key ways. According to the study, approximately 10 million of the poorest 100 million people in the Americas have some stage of the disease, which like AIDS is highly stigmatized and disproportionately affects the poor.
Chagas is neither a virus nor a bacterium, but an incurable single-celled parasite like malaria and sleeping sickness.  Rural areas and poverty stricken communities are most commonly hit with Chagas disease because, according to the Centers for Disease Control (CDC), the triatomine bug that carries the disease “thrives under poor housing conditions (for example, mud walls, thatched roofs), so in endemic countries, people living in rural areas are at greatest risk for acquiring infection.”

The bugs — also called “kissing” bugs — drink the victims’ blood, typically while they sleep, then leave their droppings near the site of the resulting wound. The droppings carry larval trypanosomes called trypanomastigotes, which penetrate skin cells around the bite wound and move on the next phase of their life cycle, when they become amastigotes, which multiply and divide until they burst free of the skin cells and enter the bloodstream as tiny worms.
At this point, the victim enters the disease’s acute stage, which is marked by fatigue, fever, nausea, vomiting, diarrhea, rashes and headaches as the body’s immune system reacts to the onslaught of worms. It is also at this stage that the parasites get taken back up into the triatomine bug, where they mate and complete the other half of their life cycle.
During the acute phase, many patients develop the most distinctive sign of the disease, called Romaña’s sign, the swelling and irritation of the inner eyelids, which is caused by contact with the fecal matter of triatomine bugs. The symptom occurs typically 1 to 2 weeks after exposure and is what earned the disease its previous name, “river blindess.”
Chagas disease, like AIDS, can have a long, asymptomatic incubation period, and in its chronic manifestation, which follows the acute phase, it is similarly devastating to the long-term health and productivity of infected individuals. In addition to overall fatigue and malaise, according to theTimes, “About a quarter of its victims eventually will develop enlarged hearts or intestines, which can fail or burst, causing sudden death. Treatment involves harsh drugs taken for up to three months and works only if the disease is caught early.”
Once the disease reaches a certain point in its development, it becomes incurable. Drugs to treat it are cheaper than AIDS drugs, but are in short supply in poorer countries. The authors of the PLoS paper argue that because Chagas is a disease of the poor, it is not a priority of governments and public health departments.
The heaviest concentrations of the disease are in Mexico, Bolivia, Colombia and in Central America. An estimated 300,000 people in the U.S. have Chagas, typically in Texas and the Gulf Coast region, most of whom are immigrants. The disease can also be transmitted from mother to child during gestation, through blood transfusions and, less commonly, in contaminated food or water.

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