TVMA - Tennessee Veterinary Medical Association

Chagas’ Disease in Tennessee Dogs


TVMA members in 30 Tennessee counties collected more than 800 canine serum samples as part of a Tennessee Department of Health study of Chagas’ disease, July–October 2008. The parasite Trypanosoma cruzi is the etiological agent of Chagas’ disease or American trypanosomiasis.  Though endemic in Latin America and the southeastern United States, autochthonous human cases are rarely seen in the US.  T. cruzi, transmitted by triatomine insects (kissing bugs), causes disease and fatality in both humans and animals .  This parasite is shed in the insect’s feces which is often left behind on the victim’s skin after a kissing bug’s blood meal. Transmission can occur when the human or animal unknowingly scratches or rubs the parasite into a wound, an eye, or the mouth.



In this study, researchers at the Tennessee Department of Health measured seroprevalence of T. cruzi in dogs from five of the eight level III ecoregions in the state.  Preliminary results from this study among dogs demonstrated antibody seroprevalence of 6.4% (55/860).  Seroprevalence had previously been reported for several wildlife species including opossums, wood rats, raccoons, armadillos, and coyotes.  

Indirect immunofluorescence assays (IFA) were used to measure the presence of antibodies to T. cruzi, followed by statistical analyses to identify factors affecting infection.  Older dogs were more likely than younger dogs to be positive for T. cruzi antibodies, likely resulting from a longer period of time to have been exposed to the kissing bugs. Similarly, outdoor dogs were more likely than indoor dogs to have T. cruzi antibodies. While kissing bugs can and do enter homes, dogs living outdoors are more likely to come into contact with these insects.  

In dogs, clinical symptoms can include an enlarged heart, lethargy, anorexia, ascites, cardiac conduction disturbances, and respiratory difficulties.   In severe chronic cases, death may occur.

Thanks to the enthusiastic participation of practitioners throughout the state, we now have a better understanding of the epidemiology of Chagas’ Disease in companion animals in Tennessee. As this disease continues to emerge in the U.S., veterinarians should consider Chagas disease as a differential diagnosis for compatible illness.

For more information about Chagas Disease, see http://www.cfsph.iastate.edu/Factsheets/pdfs/trypanosomiasis_american.pdf Specific questions about this study can be directed to Dr. Abelardo Moncayo at abelardo.moncayo@state.tn.us .

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