High Trypanosoma cruzi infection prevalence associated with minimal cardiac pathology among wild carnivores in central Texas

Abstract

Infection with the zoonotic vector-borne protozoal parasite Trypanosoma cruzi causes Chagas disease in humans and dogs throughout the Americas. Despite the recognized importance of various wildlife species for perpetuating Trypanosoma cruzi in nature, relatively little is known about the development of cardiac disease in infected wildlife. Using a cross-sectional study design, we collected cardiac tissue and blood from hunter-donated wildlife carcasses- including raccoon (Procyon lotor), coyote (Canis latrans), gray fox (Urocyon cinereoargenteus), and bobcat (Lynx rufus) – from central Texas, a region with established populations of infected triatomine vectors and increasing diagnoses of Chagas disease in domestic dogs. Based on PCR analysis, we found that 2 bobcats (14.3%), 12 coyotes (14.3%), 8 foxes (13.8%), and 49 raccoons (70.0%) were positive for T. cruzi in at least one sample (right ventricle, apex, and/or blood clot). Although a histologic survey of right ventricles showed that 21.1% of 19 PCR-positive hearts were characterized by mild lymphoplasmocytic infiltration, no other lesions and no amastigotes were observed in any histologic section. DNA sequencing of the TcSC5D gene revealed that raccoons were infected with T. cruzi strain TcIV, and a single racoon harbored a TcI/TcIV mixed infection. Relative to other wildlife species tested here, our data suggest that raccoons may be important reservoirs of TcIV in Texas and a source of infection for indigenous triatomine bugs. The overall high level of infection in this wildlife community likely reflects high levels of vector contact, including ingestion of bugs. Although the relationship between the sylvatic cycle of T. cruzi transmission and human disease risk in the United States has yet to be defined, our data suggest that hunters and wildlife professionals should take precautions to avoid direct contact with potentially infected wildlife tissues.

Risk factors and select cardiac characteristics in dogs naturally infected withTrypanosoma cruzipresenting to a teaching hospital in Texas

“…Older dogs have a higher prevalence of T. cruzi infection than younger dogs, likely because older dogs have had more opportunities for exposure. 5,8,14,49 In our study population, infected dogs were significantly younger (mean = 5.9 years; P = .006) than negative dogs (mean = 7.4 years). Dogs presenting to a teaching hospital could be more likely to have clinical disease.…”

“…2,7,8,36,37,[42][43][44][45][46] The high prevalence of dogs infected with T. cruzi likely demonstrates an established enzootic transmission cycle, as Texas harbors the highest species diversity of triatomine vectors that can transmit T. cruzi and a diversity of wildlife reservoirs. 2,5,47 The South Texas Plains ecoregion had the highest percent of infected dogs (47%), whereas the next highest region was the Edwards Plateau (32%). There is a greater than expected density of Triatoma gerstaeckeri in south central Texas, which is where we found the highest percent of infected dogs.…”

Widespread Trypanosoma cruzi infection in government working dogs along the Texas-Mexico border: Discordant serology, parasite genotyping and associated vectors

“…The parasite is transmitted by infected hematophagous triatomine insects, commonly known as ‘kissing bugs’. Chagas disease is estimated to infect nearly 6 million people throughout Latin America, and occurs across the southern US in enzootic cycles [ 1 , 2 ], where raccoons and other wildlife serve as reservoirs [ 2 , 3 ]. In many areas of Latin America, such as in the Gran Chaco ecosystem, domestic dogs are an important reservoir of T .…”

Prevalence and Seroprevalence of Trypanosoma cruzi Infection in a Military Population in Texas

“…Statistical modeling estimates that one case of vectorial transmission requires 900–4,000 contacts with an infected triatomine. 27 Second, triatomines opportunistically feed on a variety of vertebrate species—many of which are present on JBSA and have tested positive for T. cruzi infection in south-central Texas 28 , 29 —offering competitive, nonhuman blood meal sources. Third, species-specific vector competency may vary based on environmental distribution, flying and dispersal capacity, inclination to invade human dwellings, and feeding and defecation patterns.…”