Global meta-analysis on Babesia infections in human population: prevalence, distribution and species diversity

Human babesiosis is an emerging tick-borne protozoan zoonosis caused by parasites of the genus Babesia and transmitted by ixodid ticks. It was thought to be a public health problem mainly for the immunocompromised, however the increasing numbers of documented cases among immunocompetent individuals is a call for concern. In this systematic review and meta-analysis, we reported from 22 countries and 69 studies, an overall pooled estimate (PE) of 2.23% (95% CI: 1.46–3.39) for Babesia infections in humans. PEs for all sub-groups varied significantly (p Babesia species and targeted population ranged between 0.43% (95% CI: 0.41–0.44) and 7.41% (95% CI: 0.53–54.48). Babesia microti recorded the widest geographic distribution and was the predominant specie reported in North America while B. divergens was predominantly reported in Europe. Eight Babesia species; B. bigemina, B. bovis, B. crassa-like, B. divergens, B. duncani, B. microti, B. odocoilei and B. venatorum were reported in humans from different parts of the world with the highest prevalence in Europe, lower middle income countries and among individuals with history of tick bite and other tick-borne diseases. To control the increasing trend of this emerging public health threat, tick control in human settlements, the use of protective clothing by occupationally exposed people and the screening of transfusion blood in endemic countries are recommended. Abbreviations AJOL: African Journals OnLine, CI: Confidence interval, CIL: Country income level, df: Degree of freedom, HIC: Higher-income countries, HQ: High quality, I2: Inverse variance index, IFAT: Indirect fluorescent antibody test, ITBTBD: Individuals with tick-bite and tick-borne diseases, JBI: Joanna Briggs Institute, LIC: Lower-income countries, LMIC: Lower middle-income countries, MQ: Medium quality, NA: Not applicable, N/America: North America, OEI: Occupational exposed individuals, OR: Odds ratio, PE: Pooled estimates, PCR: Polymerase chain reaction, Prev: Prevalence, PRISMA: Preferred Reporting System for Systematic Reviews and Meta-Analyses, Q: Cochran’s heterogeneity statistic, QA: Quality assessment, Q-p: Cochran’s p-value, qPCR: Quantitative polymerase chain reaction, S/America: South America, Seq: Sequencing, UMIC: Upper middle-income countries, USA: United States of America人类巴贝虫病是一种新发的蜱传原生动物人畜共患病，由巴贝虫属（Babesia）寄生虫引发，并通过硬蜱（ixodid ticks）传播。此前该病被认为主要仅对免疫功能低下人群构成公共卫生威胁，但如今免疫功能正常个体中确诊病例数不断增加，这一现象需引起高度关注。本项系统评价与荟萃分析纳入22个国家的69项研究，结果显示人类巴贝虫感染的总体合并估算值（pooled estimate, PE）为2.23%（95%置信区间：1.46~3.39）。所有亚组的合并估算值均存在显著差异（p<0.001，I²=98.2%）；按巴贝虫虫种与目标人群分层的感染率估算值区间为0.43%（95%CI：0.41~0.44）至7.41%（95%CI：0.53~54.48）。微小巴贝虫（Babesia microti）的地理分布范围最广，为北美地区检出的优势虫种；而分歧巴贝虫（B. divergens）则是欧洲的优势报告虫种。全球范围内已有8种巴贝虫属寄生虫可感染人类，分别为双芽巴贝虫（B. bigemina）、牛巴贝虫（B. bovis）、克氏巴贝虫样株（B. crassa-like）、分歧巴贝虫（B. divergens）、邓肯巴贝虫（B. duncani）、微小巴贝虫（B. microti）、鹿巴贝虫（B. odocoilei）以及狩猎巴贝虫（B. venatorum）；其感染率在欧洲、中低收入国家以及有蜱叮咬史或其他蜱传疾病史的人群中最高。为遏制这一新发公共卫生威胁的上升趋势，建议在人类聚居区开展蜱虫防控、职业暴露人群穿戴防护衣物，以及在流行地区对供血血液进行筛查。 缩写说明： AJOL：非洲在线期刊（African Journals OnLine） CI：置信区间（Confidence interval） CIL：国家收入层级（Country income level） df：自由度（Degree of freedom） HIC：高收入国家（Higher-income countries） HQ：高质量（High quality） I²：逆方差指数（Inverse variance index） IFAT：间接荧光抗体试验（Indirect fluorescent antibody test） ITBTBD：有蜱叮咬史及蜱传疾病史人群（Individuals with tick-bite and tick-borne diseases） JBI：乔安娜·布里格斯研究所（Joanna Briggs Institute） LIC：低收入国家（Lower-income countries） LMIC：中低收入国家（Lower middle-income countries） MQ：中等质量（Medium quality） NA：不适用（Not applicable） N.America：北美洲（North America） OEI：职业暴露人群（Occupational exposed individuals） OR：比值比（Odds ratio） PE：合并估算值（Pooled estimates） PCR：聚合酶链式反应（Polymerase chain reaction） Prev：感染率（Prevalence） PRISMA：系统评价与荟萃分析首选报告条目（Preferred Reporting System for Systematic Reviews and Meta-Analyses） Q：科克兰异质性统计量（Cochran’s heterogeneity statistic） QA：质量评估（Quality assessment） Q-p：科克兰p值（Cochran’s p-value） qPCR：定量聚合酶链式反应（Quantitative polymerase chain reaction） S.America：南美洲（South America） Seq：测序（Sequencing） UMIC：上中收入国家（Upper middle-income countries） USA：美利坚合众国（United States of America）