Dynamic investigation on the co-infection status of two pathogens in ticks from tourist point in Heilongjiang province / 中华流行病学杂志

ABSTRACT

Objective To monitor the co-infection status of Borrelia burgdorferi sensu lato (R.b.s.1) and spotted fever group Rickettsia (SFGR) in tourist areas of Heilongjiang province.Methods Polymerase chain reaction (PCR) was used to detect the 5S-23S rRNA intergenic spacer of B.b.s.1 and ompA of SFGR in ticks,dynamically collected from tourist areas of Heilongjiang province in 2010.Amplification products from positive ticks were sequenced,and phylogenetic analysis was conducted by Mega 5.0 software package.Results 849 ticks were collected from two tourist points,with the dominant ticks in Tiger Mountain and Jingpo Lake were Ixodes persulcatus and Haemaphysalis concinna.Regarding the Ixodes persulcatus from Tiger Mountain,the infection rates of B.b.s.1 and SFGR were 26.15％ and 10.05％.The infection rate of SFGR was 13.33％ in Haemaphysalis concinna and the B.b.s.1 was tndiscovered in the same ticks from Jingpo Lake.However,the co-infection could only be detected in Ixodes persulcatus of both tourist areas.Surveillance data showed that the major ticks were more likely to be appeared in July at Tiger Mountain and in June at Jingpo Lake.Data from the sequence analysis on B.b.s.1 showed that the B.b.s.1 in tourist areas could be classified into three different genotypes,other than B.garinii and B.afzelii.We first detected B.valaisiana-like group genotype in northeast of China.Results from the sequence analysis of SFGR positive products showed that the two DNA sequences of newly detected agents were completely the same as Rickettsia sp.HL-93 which was detected in Hulin and Rickettsia sp.H820 found in northeast,China.Conclusion The co-infection of B.b.s.1 and SFGR was detected in ticks from the tourist areas of Heilongjiang province,and data from the sequencing of specific fragment showed that various kinds of genotypes existed in this area.However; the rates of co-infectionitis-different according to environment,time and population that contributed to the kinds of and the index of ticks existed in the surveys points,also the infection rate of the ticks was studied.