Evidence of canine infections with spotted fever-group rickettsiae in southwestern and east central Indiana
A serosurvey was conducted to determine rickettsial infection rates in dogs from two distinct areas in Indiana. Sera were collected from dogs and tested for the presence of antibodies to R. rickettsii, R. montana, R. rhipicephali, and R. bellii using the micro-immunofluoresence test. Results from this study indicate an association between canine and human rickettsial infections. Dogs in southwestern Indiana were found to have significantly higher rickettsial infection rather than those in east central Indiana. Human RMSF cases have also been reported more frequently from southern Indiana.All rickettsial species were detected at some level, with many dogs reacting to more than one antigen Evidence suggests that R. montana is the predominant rickettsial species in Indiana. In addition, indicative of a more suitable tick habitat, dogs sampled from rural areas were seropositive more frequently than the urban/suburban dogs. This study suggests that dogs are exposed to the same tick population as humans and can serve as indicators of the presence of rickettsial agents. Indiana residents should be aware of the potential for RMSF transmission throughout the state.