RESUMO
The Mexican free-tailed bat (Tadarida brasiliensis) is one of the most abundant mammals in North America. Mexican free-tailed bats have a wide geographic range stretching from northern South America to the western United States. Bats are theorized to be the original hosts for Trypanosoma cruzi -the causative agent of Chagas disease- and can serve as a source of infection to triatomine insect vectors that feed upon them. Chagas disease is a neglected tropical disease across the Americas where triatomines are present, including the southern United States, where Texas reports this highest number of locally-acquired human cases. To learn more about the role of bats in the ecology of Chagas disease in Texas, we surveyed a colony of Mexican free-tailed bats from Brazos County, Texas, for T. cruzi using carcasses salvaged after an extreme weather event. A total of 283 Mexican free-tailed bats collected in February 2021 were dissected and DNA from the hearts and kidneys was used for T. cruzi detection via qPCR. None of the bat hearts or kidneys tested positive for T. cruzi; this sample size affords 95% confidence that the true prevalence of T. cruzi in this population does not exceed 1%. Future sampling of multiple bat species as well as migrant and resident colonies of Mexican free-tailed bats across different times of the year over a broader geographic range would be useful in learning more about the role of bats in the ecology of Chagas disease in Texas.
Assuntos
Doença de Chagas , Quirópteros , Trypanosoma cruzi , Animais , Quirópteros/parasitologia , Texas/epidemiologia , Trypanosoma cruzi/isolamento & purificação , Doença de Chagas/veterinária , Doença de Chagas/epidemiologia , Doença de Chagas/parasitologia , Masculino , FemininoRESUMO
BACKGROUND: Chagas disease is increasingly recognized in the southern U.S., where triatomine vectors transmit Trypanosoma cruzi among wildlife and domestic dogs with occasional vector spillover to humans. As in humans, clinical outcome in dogs is variable, ranging from acute death to asymptomatic infections or chronic heart disease. In order to characterize cardiac manifestations of T. cruzi infections, we tracked a cohort of naturally-infected dogs and a matched cohort of uninfected dogs. We hypothesized that selected measures of cardiac disease (abnormal rate, abnormal rhythm, and elevated cardiac troponin I (cTnI; a biomarker of cardiac injury)) would occur more commonly in infected than uninfected dogs matched by age, breed, sex and location. In addition to the clearly positive and negative dogs, we specifically tracked dogs with discordant test results across three independent serological assays to gather clinical data that might elucidate the infection status of these animals and inform the utility of the different testing approaches. RESULTS: We placed an ambulatory ECG monitor (Holter) on 48 government working dogs and analyzed 39 successful recordings that met length and quality criteria from 17 T. cruzi-infected, 18 uninfected dogs and 4 dogs with discordant results. Overall, 76.5% of positive, 100.0% of discordant, and 11.1% of negative dogs showed > 1 ECG abnormality (p < 0.0001), and positive and discordant dogs had a higher mean number of different types of ECG abnormalities than negative dogs (p < 0.001-0.014). The most common cardiac abnormalities included supraventricular and ventricular arrhythmias and atrioventricular block. Positive dogs had higher serum concentrations of cTnI than both negative dogs (p = 0.044) and discordant dogs (p = 0.06). Based on dog handler reports, nearly all (4/5; 80%) dogs with reported performance decline or fatigue were T. cruzi-infected dogs. CONCLUSIONS: Further understanding cardiac manifestations in dogs naturally infected with T. cruzi is critical for prognostication, establishing a baseline for drug and vaccine studies, and better understanding of zoonotic risk.
Assuntos
Doença de Chagas/veterinária , Doenças do Cão/parasitologia , Cardiopatias/veterinária , Animais , Arritmias Cardíacas/complicações , Arritmias Cardíacas/veterinária , Doença de Chagas/complicações , Doença de Chagas/epidemiologia , Doenças do Cão/epidemiologia , Cães , Eletrocardiografia Ambulatorial/veterinária , Feminino , Masculino , Testes Sorológicos/veterinária , Texas/epidemiologia , Troponina I/sangue , Trypanosoma cruzi/isolamento & purificaçãoRESUMO
National parks attract millions of visitors each year. Park visitors, employees, and pets are at risk of infection with various zoonotic pathogens, including Trypanosoma cruzi, causative agent of Chagas disease. Big Bend National Park is located along the Texas-Mexico border in a region with endemic triatomine insects- vectors of T. cruzi- yet the degree to which the parasite is transmitted in this region is unknown. We collected triatomines for T. cruzi detection and discrete typing unit (DTU) determination, and conducted blood meal analyses to determine recent hosts. As an index of domestic/peridomestic transmission, we tested residential dogs in the Park for exposure to T. cruzi. From 2015 to 2017, 461 triatomines of three species-Triatoma rubida, Triatoma gerstaeckeri, and Triatoma protracta-were collected in and around the Park. Adult triatomine encounters peaked in June of each year (52.8% of collections). We detected an overall infection prevalence of 23.1% in adult triatomines (n = 320) and 4.2% in nymph triatomines (n = 24). DTU TcI was the only T. cruzi strain detected. Of 89 triatomines subjected to blood meal analyses, vertebrate host DNA was successfully amplified from 42 (47.2%); blood meal sources included humans, domestic animals, and avian and mammalian wildlife species. Tested dogs were considered positive if reactive on at least two independent serologic assays; we found 28.6% seroprevalence in 14 dogs. These findings reveal interactions between infected triatomines, humans, dogs, and wildlife in and around Big Bend National Park, with potential risk of human disease.