Prevalence of infection with Francisella tularensis, Borrelia burgdorferi sensu lato and Anaplasma phagocytophilum in rodents from an endemic focus of tularemia in Bulgaria.

The prevalence of Francisella tularensis, Borrelia burgdorferi and Anaplasma phagocytophilum in rodents is a determinant for their role in maintaining pathogens in the environment. A total of 169 rodents, trapped in an endemic focus of tularemia, were examined by PCR to asses the frequency of infection with the etiological agents of tularemia, Lyme borreliosis and human granulocytic anaplasmosis. The overall prevalence of F. tularensis was 22 %. In 6 % of the black rats, F. tularensis was identified in coinfection with B. burgdorferi and in 3 % in coinfection with A. phagocytophilum. B. burgdorferi and A. phagocytophilum were detected in 26 % and 8 % of the trapped rodents. Results obtained show the existence of an active natural focus of tularemia. The high level of coinfections indicated that the endemic focus is mixed and generates risk for multiple infections in humans. Further investigations are needed to reveal interactions between the pathogens in the infected animals.