Prevalence and molecular identification of Borrelia spirochetes in Ixodes granulatus ticks collected from Rattus losea on Kinmen Island of Taiwan.

Li-Lian Chao,Li-Ling Liu,Chien-Ming Shih

doi:10.1186/1756-3305-5-167

Abstract

BackgroundIxodes granulatus is widely distributed in various countries of Southeast Asia and Taiwan. Although this tick species is presumed to be the vector for the enzoonotic transmission of Borrelia spirochetes in the Taiwan area, the prevalence of infection and genetic diversity of Borrelia spirochetes harbored by this tick species need to be further determined.MethodsDNA extraction was performed from individual tick specimens collected from Rattus losea on Kinmen Island of Taiwan. Borrelia infection in I. granulatus ticks was detected by performing a specific PCR assay based on the 5S-23S intergenic spacer amplicon gene of B. burgdorferi sensu lato. The genetic identities of detected spirochetes were identified by gene sequencing and phylogenetic analysis.ResultsBorrelia infection was detected in nymph, male, and female stages of Ixodes granulatus ticks with an infection rate of 42.9%, 36%, and 52.7%, respectively. Genospecies identification reveals that B. valaisiana is the main genotype (70.7%) as compared to the genotype of B. burgdorferi sensu stricto (15.4%). Phylogenetic analysis revealed that these detected spirochetes were genetically affiliated to the genospecies B. valaisiana and B. burgdorferi sensu stricto, with a high sequence homology within the genospecies of B. valaisiana (95.8 to 100%) and B. burgdorferi sensu stricto (97.2 to 100%), respectively.ConclusionsThis study highlights the significance of high prevalence and genetic diversity of Borrelia spirochetes in I. granulatus ticks collected from Rattus losea on Kinmen Island of Taiwan. Intraspecific analysis also revealed that B. valaisiana species detected in Kinmen Island can be easily distinguished from the European group of B. valaisiana and other genospecies of Borrelia spirochetes. This may imply an enzoonotic cycle between I. granulatus ticks and rodent hosts that maintains Borrelia spirochetes in Kinmen Island as well as Southeast Asia.

Highlights

Ixodes granulatus is widely distributed in various countries of Southeast Asia and Taiwan
polymerase chain reaction (PCR) detection of Borrelia infection in I. granulatus ticks To verify the existence of Borrelia spirochetes in I. granulatus ticks removed from rodents of Kinmen Island
Results indicate that Borrelia infections were detected in 52.7% (69/131) of females, 36% (9/25) of males, and 42.9% (45/105) of nymphs of I. granulatus ticks (Table 2)

Summary

Introduction

Ixodes granulatus is widely distributed in various countries of Southeast Asia and Taiwan. This tick species is presumed to be the vector for the enzoonotic transmission of Borrelia spirochetes in the Taiwan area, the prevalence of infection and genetic diversity of Borrelia spirochetes harbored by this tick species need to be further determined. The hard tick of I. granulatus was presumed to be the tick vector for the enzoonotic transmission of Borrelia spirochetes in the Taiwan area [21], the prevalence of infection and genetic diversity of Borrelia spirochetes harbored by this tick species in Kinmen Island needs to be further defined

Methods

Results

Discussion

Conclusion