Chagas Disease in Dogs: Is It Transmissible to Humans?

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Chagas disease (also known as American trypanosomiasis) is a parasitic vector-borne disease. This disease is found mainly in Central and South America and in the southern United States. The parasite is a flagellated protozoan named Trypanosoma cruzi (T. cruzi) that can infect over 100 species of mammals and cause heart disease. The vector is a reduviid or Triatominae insect also known as a "kissing bug" or "assassin bug." About 300,000 people are diagnosed in the U.S. with Chagas disease; most are due to infections acquired outside of the United States (immigrants and travelers). Worldwide estimates range from about 7.5 to 15 million infected individuals.

The parasites are often referred to as "viruses," but this is incorrect. The parasites are flagellated protozoans (T. cruzi) that have a complicated life cycle (see for example, reference one) and are transmitted to mammals and humans by the bite of the vector, the "kissing bug." The development of Chagas disease in dogs is similar to the development of Chagas disease in humans. Some dogs may not develop any clinical symptoms until entering a chronic phase of the disease, which may be several years after initial infection. The clinical signs in dogs during the acute phase are fever, anorexia, lethargy, swollen lymph nodes, and an enlarged liver or enlarged spleen. After the acute phase, there may be a latent phase that is asymptomatic and may last for several years. The chronic phase usually begins with right-sided heart failure that may develop into chronic myocarditis. Arrhythmias of the heart may develop and result in sudden death of the dog.