Rodents as reservoirs of human pathogens in Bulgaria

Abstract

Small mammals are reservoirs of various human pathogens. The aim of this work was to investigate infections with human pathogens in rodents trapped in different regions of Bulgaria. A total of 284 rodents were investigated by PCR for detection of the flagellin gene of borreliae within Borrelia burgdorferi sensu lato complex, ankA gene of Anaplasma phagocytophilum and nucleoprotein gene of hantavirus Dobrava - conventional nested RT-PCR and Real Time PCR with TaqMan probe. B. burgdorferi was detected in 64/284 (22.5%) of the investigated rodents by PCR. Of them, 41 samples originated from Apodemus flavicollis, 20 from A. agrarius, and 3 from A. sylvaticus. Overall, 33 of the investigated 284 rodents were infected with Anaplasma phagocytophilum (11.6%) - 11 Apodemus flavicollis (infectivity rate 8.6% of the 128 investigated), 13 Apodemus agrarius (infectivity rate 13.5% of the 96 tested), and 1 Apodemus sylvaticus (infectivity rate 9% of the 11 tested). Hantavirus RNA was detected in 9 of the rodents. Only Dobrava-Belgrade virus but not Puumala or Saaremaa virus was detected. Almost all infected rodents were A. flavicollis (8/9 PCR-positive rodents). Rodents are important reservoirs of human pathogens. In this study, active infection in rodents was confirmed by detection of microorganism's genome. Remarkably, a high number of rodents from genus Apodemus were infected with borreliae. The high rate of detection of A. phagocytophilum in rodents from A. agrarius species suggested that this species might serve as major reservoir of human anaplasmosis in Bulgaria. Mainly infected with hantaviruses were A. flavicollis mice, known as reservoir of Dobrava hantavirus but hantavirus infections were detected also in A. agrarius mice. Medical authorities should be aware of the risk for humans.