Dogs Found to Play Important Role in Chagas Disease

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Chagas disease is caused by a parasite called Trypanosoma cruzi (T.cruzi) and affects about 10 to 12 million people in Latin America, killing about 15,000 a year. Public health officials working to combat the infectious disease have found that malnourished dogs among the rural poor are an important target to control T. cruzi transmission.

Trypanosoma cruzi is transmitted between animals by the triatomine insect or “kissing bug”, which sucks the blood of mammals. The bug can then transmit the disease to humans. Dogs are 14 times more effective at spreading Chagas disease than humans.

Dogs are easily accessible to the bugs, says disease ecologist Uriel Kitron, chair of environmental studies at Emory University who has researched Chagas disease in northern Argentina for 10 years, because they lie on porches or against the nooks and crannies of mud-brick dwellings.

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Kitron’s work is included in a June 24 special supplement of Nature.

Chagas disease begins as an acute infection that can subside on its own. Symptoms include a mild swelling at the site of the infection. In one out of three cases, however, the infection persists and can go unnoticed for decades, until it causes complications such as heart failure, malformation of the intestines, and sudden cardiac death. Currently available medications are highly toxic and often ineffective.

Chagas disease primarily occurs in rural areas of Mexico, Central America and South America but human migration has moved Chagas disease around the globe. Because the disease can be spread by blood transfusion, blood banks in the US must now screen donors for T. cruzi.

The current strategy for controlling Chagas disease is to spray insecticide. An alternative may be to identify dogs at highest risk and provide them with insecticide collars instead, according to Kitron.

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