Molecular Epidemiological Investigation Of Babesia Microti In Some Small Rodents And Captive Monkey Populations In China

Babesiosis,an animal parasitosis that appears in large parts of the world,is an emerging tick-transmitted zoonosis.This study was designed to estimate the presence of Babesia microti among small rodents in Yunnan Province,where human cases have been reported.However,the distribution of Babesia in endemic region was largely unknown.In this study,1672 small wild rodents were cataloged,comprising 4 orders,in 9 areas in the western Yunnan province from 2009 to 2011.Babesia microti DNA was detected by polymerase-chain-reaction(PCR)in 4.3%(72/1672)of the rodents.The most frequently infested species included Crocidura lasiura,Berylmys bowersi,Niviventer fulvescens,Tupaia belangeri,and Apodemus chevrieri.Rodents in forest and shrub had significantly higher infection rates.Furthermore,the Lanping(20/115,17.4%),Lianghe(11/141,7.8%)and Teng chong regions(18/286,6.3%)exhibited the highest rates.Moreover,three B.microti variants were identified,including Yunnan-1(GenBank accession number KC147722)in 49 rodents,Yunnan-2(GenBank accession number KC147723)in 13 rodents and Yunnan-3(GenBank accession number KC147724)in 10 rodents.Genetic comparisons revealed that Babesia demonstrated highest similarity to those found in Kobe and Otsu-type in Japan.A variety of rodent species might be involved in enzootic maintenance and transmission of B.microti,suggesting further serological investigations in humans are warranted.Additionally,few Babesia species had been proved that they could infect humans and increased risk of causing human disease.Its wide distribution should be gaining intense attention.As we know,the relationship between non-human primates and human is close.Therefore,non-human primates play an indispensable role in leading and supporting life science research,biotechnology innovation and the development of biological medicine industry.In this study,Babesia microti DNA was detected by PCR in 38(5.97%)of 636 Old World monkey species(Macaca fascicularis and Macaca mulatta)in Chinese mainland.The positive rates of B.microti in Macaca fascicularis and Macaca mulatta was 3.2% and 8.53% respectively.However,the infection of B.microti in Old World monkeys in China's mainland had no relationship with gender and age(P>0.05).Moreover,18 S rRNA gene of 7 randomly selected isolates were sequenced and compared with sequences obtained from GenBank.The results showed that the sequences of the selected isolates had 98 % homologous identities with that of B.microti isolate MM-1(EU168705),with only 11-bp mutations were observed,indicating a close relationship between these isolates.The results of present study demonstrated that B.microti can infect monkeys.However,whether serve as reservoir hosts for B.microti needs to be further elucidated.In conclusion,a variety of rodent species were found to be involved in the enzootic maintenance and transmission of B.microti.Future investigations are warranted to determine the potential risk of infection in local residents.The most common mode of infection was through tick bites,supporting the need for further investigation into ticks as the important carriers of B.microti.Furthermore,The results of present study demonstrated that B.microti can infect monkeys.However,whether macaques serve as reservoir hosts for B.microti needs to be further elucidated.