A broad-range survey of Borrelia burgdorferi sensu lato infection in small mammals in Sino-Burmese border area, Yunnan Province, China

Abstract Background: Lyme disease is caused by Borrelia burgdorferi sensu lato which is usually found in wild and domestic mammals worldwide. In China, Human cases of B. burgdorferi infections have been identified in a wide distribution, but little direct surveillance of potential rodent reservoirs has been performed in Yunnan Province, the tropical region, Sino-Burmese border area, southwestern China. Here we report a thoroughly investigation of B. burgdorferi sensu lato in small mammals collected in 2011 to 2016 in the region.Methods: A nested PCR was done for the 5S-23S rRNA intergenic spacer gene of Borrelia burgdorferi sensu lato. The PCR-positive amplicons were directly sequenced. Sequence analysis was carried out using a FASTA search on the Genbank database, with phylogenetic trees constructed using MEGA software, version 6.06. Statistical Analysis were conducted using SPSS.version 17.0.Results: Totally 57 species, 3659 mammals were captured at 159 sample sites located in 23 counties in Yunnan Province. Thirty species, 146 (3.99%) mammals were tested positive for B. bourgdorferi s.l . by nested PCR based on 5S-23S rRNA intergenic spacer gene. 20 species mammals were first reported infected with B. burgdorferi s.l. Sequence analysis revealed that five genotypes of B. burgdorferi s.l. were detected, including B. afzelii , B. burgdorferi sensu stricto, B. japonica , B. garinii and B. valaisiana.Conclusions: Significant differences in prevalence rates of B. bourgdorferi s.l were observed at varying landscape types and altitudes. Small mammals in forested areas had higher prevalence rates than other landscape types as did small mammals found at altitudes greater than 2500 meters. The 5S-23S rRNA intergenic spacer gene revealed that there were five genotypes of B. burgdorferi s.l. detected, indicating high genetic diversity within this province.