American Trypanosomiasis (Chagas Disease) in dogs

Trypanosomiasis is caused by the protozoan T. cruzi. A small number of cases have been reported, principally in the southwestern United States, Texas, and California. Raccoons, opossums, armadillos, rats, cats, and dogs serve as the principal reservoirs.

Dogs (and humans) acquire the disease from a family of insects called kissing bugs, so named because they come out of cracks at night and bite the face of sleepers. Infection occurs through contamination of the bug bites by the insects’ feces. Another source of infection in dogs is feeding on a host (such as a raccoon) that harbors encysted larvae in its tissues.

Signs include fever, weakness, enlargement of the lymph nodes and spleen, and inflammation of the spinal cord and brain. Trypanosomiasis attacks the heart muscle, causing myocarditis with heart arrhythmias. This can lead to collapse and death. Another complication of myocarditis is congestive heart failure one to three years later.

The diagnosis is made by identifying the protozoan in blood smears. Serology tests also are available.

Treatment: Experimental drugs have been used, but the response is poor.

Public health considerations: Because this often fatal disease can be transmitted to humans through intermediate hosts, euthanizing the animal is recommended. It is essential to take the utmost precautions when handling infected animals, as well as their blood and discharges.