PLoS ONE：莱姆病或可增加巴贝西虫病的传播

  来自耶鲁大学公共卫生学院的研究人员近日在PLoS ONE上刊登文章表示，他们利用数学模型，通过实地调查及实验室研究发现，感染伯氏疏螺旋体引发的莱姆病的小鼠或许也会增加传播田鼠巴贝虫的风险，田鼠巴贝虫是一种引发巴贝西虫病的病原体，而这两种疾病都可以通过黑腿蜱叮咬的方式传播给人类。

  本研究同时也证明了为何人类巴贝西虫病仅仅发生在莱姆病发生的区域，研究者Diuk-Wasser说道，蜱和天然宿主在自然界中常常都是共感染的，因此揭示这些病原体影响宿主的机制及其分布对于开发抑制疾病传播的策略非常关键。研究者发现伯氏疏螺旋体和田鼠巴贝虫在宿主蜱中的感染概率远比想象中要高，这就增加了人类暴露的风险，而且伯氏疏螺旋体和田鼠巴贝虫共感染的蜱叮咬人类后引发的症状更为严重，有时候甚至很难被诊断出来。

  目前95%的莱姆病集中于美国14个州，每年的新发病例将近3万，研究者在相似的区域也发现了巴贝虫病，但95%的巴贝西虫病仍主要集中于美国7个州，即康涅狄格州、马萨诸塞州、新泽西州、纽约州、罗得岛州、明尼苏达州及威斯康星州，每年新增巴贝西虫病大约有1000例。

  当两种疾病使得患者出现部分相同的症状时，巴贝西虫病对免疫力受损的患者具有潜在的致命性，其可以通过输血及蜱叮咬进行传播，是威胁人类健康的一大杀手；本研究中，研究者利用精准化的数学模型可以更好地预测哪些区域具有传播田鼠巴贝虫的风险，且还可以评估新方法是否可以减少伯氏疏螺旋体通过蜱的感染。（转化医学网360zhyx.com）

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Borrelia burgdorferi Promotes the Establishment of Babesia microti in the Northeastern United States
PLoS ONE DOI: 10.1371/journal.pone.0115494
Jessica M. Dunn, Peter J. Krause, Stephen Davis, Edouard G. Vannier, Meagan C. Fitzpatrick, Lindsay Rollend, Alexia A. Belperron, Sarah L. States, Andrew Stacey, Linda K. Bockenstedt, Durland Fish, Maria A. Diuk-Wasser.
Babesia microti and Borrelia burgdorferi, the respective causative agents of human babesiosis and Lyme disease, are maintained in their enzootic cycles by the blacklegged tick (Ixodes scapularis) and use the white-footed mouse (Peromyscus leucopus) as primary reservoir host. The geographic range of both pathogens has expanded in the United States, but the spread of babesiosis has lagged behind that of Lyme disease. Several studies have estimated the basic reproduction number (R0) for B. microti to be below the threshold for persistence (<1), a finding that is inconsistent with the persistence and geographic expansion of this pathogen. We tested the hypothesis that host coinfection with B. burgdorferi increases the likelihood of B. microti transmission and establishment in new areas. We fed I. scapularis larva on P. leucopus mice that had been infected in the laboratory with B. microti and/or B. burgdorferi. We observed that coinfection in mice increases the frequency of B. microti infected ticks. To identify the ecological variables that would increase the probability of B. microti establishment in the field, we integrated our laboratory data with field data on tick burden and feeding activity in an R0 model. Our model predicts that high prevalence of B. burgdorferi infected mice lowers the ecological threshold for B. microti establishment, especially at sites where larval burden on P. leucopus is lower and where larvae feed simultaneously or soon after nymphs infect mice, when most of the transmission enhancement due to coinfection occurs. Our studies suggest that B. burgdorferi contributes to the emergence and expansion of B. microti and provides a model to predict the ecological factors that are sufficient for emergence of B. microti in the wild.