Seroprevalence and risk factors of bluetongue virus in domestic cattle, sheep, goats and camels in Africa: a systematic review and meta-analysis

Bluetongue (BT) is a vector-borne disease affecting wild and domestic ruminants in many parts of the world. Although bluetongue virus (BTV) is widespread in ungulates in Africa, available epidemiological information on BT in this continent is limited. This systematic review and meta-analysis aimed to estimate the seroprevalence of BTV and summarize information on associated risk factors in domestic ruminants and camels in Africa. Systematic searches were conducted from the inception of the database to November 2022 on PubMed/MEDLINE, ScienceDirect, Web of Science, and Google/Google Scholar. Forty-four eligible publications were identified, published in the range from 1973 to 2020, and statistically analyzed. The pooled overall seroprevalence of BTV was 45.02% (95% confidence interval [CI]: 36.00-54.00%). The pooled seroprevalence was 49.70% (95% CI: 34.50-65.00%) in cattle, 47.00% (95% CI: 29.90-64.50%) in goats, 40.80% (95% CI: 19.60-63.90%) in camels, and 36.30% (95% CI: 29.00-44.90%) in sheep. The pooled seroprevalence decreased after 1990 and increased again after 2010. The highest pooled overall seroprevalence was found in the southeastern region, and the highest pooled overall seroprevalence was obtained by Competitive Enzyme-Linked Immunosorbent Assay. Finally, the seroprevalence in females (53.30%, 95% CI: 34.80-71.00%) was significantly higher than in males (28.10%, 95% CI: 17.40-40.30%) (<i>p</i> &lt; 0.05). We showed that antibodies against BTV were common in African ruminants and camels. Monitoring the seroprevalence of BTV, as well as systematic and continuous surveillance of the <i>Culicoides</i> population, are encouraged to prevent and control the spread of BT.

蓝舌病（Bluetongue, BT）是一种经媒介传播的疾病，可感染全球多地的野生与家养反刍动物。尽管蓝舌病毒（Bluetongue Virus, BTV）在非洲有蹄类动物中广泛分布，但该大陆关于BT的现有流行病学资料仍较为有限。本系统综述与荟萃分析旨在评估非洲地区家养反刍动物及骆驼的BTV血清阳性率，并总结相关危险因素的研究信息。研究通过系统检索，以各数据库建库时至2022年11月为时间范围，检索了PubMed/MEDLINE、ScienceDirect、Web of Science及Google/Google Scholar等平台。最终纳入44篇符合标准的文献，发表时间跨度为1973年至2020年，并对其进行了统计学分析。BTV的总体合并血清阳性率为45.02%（95%置信区间[CI]：36.00~54.00%）。其中牛的合并血清阳性率为49.70%（95%CI：34.50%~65.00%），山羊为47.00%（95%CI：29.90%~64.50%），骆驼为40.80%（95%CI：19.60%~63.90%），绵羊为36.30%（95%CI：29.00%~44.90%）。合并血清阳性率在1990年后呈下降趋势，2010年后再次回升。总体合并血清阳性率最高的区域为非洲东南部，而检测方法中以竞争性酶联免疫吸附试验（Competitive Enzyme-Linked Immunosorbent Assay）得到的合并阳性率最高。此外，雌性动物的血清阳性率（53.30%，95%CI：34.80%~71.00%）显著高于雄性动物（28.10%，95%CI：17.40%~40.30%）（P<0.05）。本研究证实，BTV抗体在非洲反刍动物与骆驼中普遍存在。为预防和控制BT的传播，建议开展BTV血清阳性率监测，并对库蠓（Culicoides）种群进行系统性、持续性的监测。