METHODS: From 2005-2008, serum samples from 706 raccoons (Procyon lotor) from 10 counties and 860 canine serum samples from 31 counties in Tennessee were tested for antibodies reactive with T. cruzi using the indirect fluorescent antibody assay. During this time, seven kissing bugs were collected and tested.
RESULTS: Two hundred six (29.2%) raccoon samples were seropositive, with 9 counties yielding positive samples (range 14.6–63.6%). Significantly more raccoons from rural habitats (35.1%) were found positive for T. cruzi exposure than were those from suburban habitats (23.1%, P < 0.001). Land cover class was not associated with seropositivity status (P = 0.441), even though deciduous forest was the most common site from where raccoons were trapped and the most common site of positive raccoons in rural areas (42%). Interestingly, age was positively associated with seropositivity. Raccoons older than 1 yr (adults) were 40.1% seropositive compared to 12.2% of those less than 1 yr (juveniles; P < 0.001). In addition, we report a seroprevalence of 6.4% among 860 canines from 31 counties and 5 ecoregions throughout Tennessee. Statistically significant associations between seropositivity and age, weight, and outdoor living were noted. Four out of seven (57.1%) of kissing bugs tested by PCR were positive for T. cruzi. Trypanosoma cruzi in the 4 positive kissing bugs samples appear to be type IIa when a portion of the MSH2 gene was sequenced.
CONCLUSIONS: This study contributes to understanding the dynamics of T. cruzi exposure within raccoon populations in Tennessee. The importance of habitat (rural vs. suburban) and microhabitat (dens) in risk of exposure to these populations is also discussed. Greater attention should be given to possible T. cruzi transmission in Tennessee and veterinarians should consider Chagas’ disease as a differential diagnosis with compatible signs. Given the widespread seropositivity of wildlife and canines to T. cruzi, the diagnosis of autochthonous transmission and finding of T. cruzi infected kissing bugs in Tennessee, we made Chagas disease a reportable disease our state in 2010.