Molecular Detection of Spotted Fever Group Rickettsiae and Ehrlichia in Rodents from Anhui Province, China

Background: Rickettsioses are important zoonotic diseases worldwide. Rickettsia are naturally maintained in vertebrate hosts and can emerge or reemerge with serious public health implications. Rodents are important host animals for many rickettsial pathogens. In China, several species of rickettsia have been reported in tick species, and few have been reported in vertebrate host animals, including rodents. Epidemiological studies that investigate natural foci and the role of small mammals in the transmission of zoonoses to humans are still needed. Thus, we investigated the presence of rickettsial agents in rodents from Anhui Province, China. Methods: A total of 143 rodents, including 131 Apodemus agrarius and 12 Niviventer niviventer, were captured alive using cage traps in the fields of four areas in Anhui Province. Tissue samples were collected aseptically from each rodent. DNA samples from rodent tissues were amplified by PCR based on rickettsial genes: the 17-kilodalton antigen gene ( 17-kDa ), 16S rRNA gene (rrs) and citrate synthase gene ( gltA ). Positive amplicons were sequenced and confirmed by BLAST analysis. Phylogenetic analysis was performed by Mega 7.0 software. Results: The overall prevalence rate of rickettsial agents in rodents was 11.9% (17/143). The genes encoding the common rickettsial 17-kDa , gltA , and 16S rRNA were positively detected in 2.1% (3/143), 5.6% (8/143) and 4.2% (6/143) of the rodents, respectively, by nested PCR. The rickettsial agents detected included Rickettsia raoultii, Rickettsia japonica and Ehrlichia chaffeensis according to BLAST and phylogenetic analysis. Conclusion: This study demonstrates the presence of rickettsial agents in rodents captured in Anhui Province, China. Further epidemiological studies should be investigated in arthropod vectors, host animals and humans to estimate the impact of rickettsia infestations among rodents from these areas.