Background A peri-urban outbreak of Rift Valley fever virus (RVFV) among dairy cattle from May through August 2018 in northern Tanzania was detected through testing samples from prospective livestock abortion surveillance. We sought to identify concurrent human infections, their phylogeny, and epidemiologic characteristics in a cohort of febrile patients enrolled from 2016-2019 at hospitals serving the epizootic area. Methods From September 2016 through May 2019, we conducted a prospective cohort study that enrolled febrile patients hospitalized at two hospitals in Moshi, Tanzania. Archived serum, plasma, or whole blood samples were retrospectively tested for RVFV by PCR. Human samples positive for RVFV were sequenced and compared to RVFV sequences obtained from cattle through a prospective livestock abortion study. Phylogenetic analysis was performed on complete RVFV genomes. Results Among 656 human participants, we detected RVFV RNA in four (0.6%), including one death with hepatic necrosis and other end-organ damage at autopsy. Humans infected with RVFV were enrolled from June through August 2018, and all resided in or near urban areas. Phylogenetic analysis of human and cattle RVFV sequences demonstrated that most clustered to lineage B, a lineage previously described in East Africa. A lineage E strain clustering with lineages in Angola was also identified in cattle. Conclusion We provide evidence that an apparently small RVFV outbreak among dairy cattle in northern Tanzania was associated with concurrent severe and fatal infections among humans. Our findings highlight the unidentified scale and diversity of inter-epizootic RVFV transmission, including near and within an urban area.

中文翻译：

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坦桑尼亚北部人类和奶牛暴发裂谷热的流行病学和基因组学特征


背景 2018 年 5 月至 8 月，坦桑尼亚北部奶牛中爆发了裂谷热病毒 （RVFV） 的城郊疫情，通过检测来自潜在牲畜流产监测的样本。我们试图在 2016-2019 年在动物流行区医院招募的一组发热患者中确定并发的人类感染、其系统发育和流行病学特征。方法 从 2016 年 9 月到 2019 年 5 月，我们进行了一项前瞻性队列研究，招募了在坦桑尼亚莫希的两家医院住院的发热患者。通过 PCR 回顾性检测存档的血清、血浆或全血样本的 RVFV。对 RVFV 阳性的人类样本进行测序，并与通过前瞻性牲畜流产研究从牛获得的 RVFV 序列进行比较。对完整的 RVFV 基因组进行系统发育分析。结果 在 656 名人类参与者中，我们在 4 名 （0.6%） 中检测到 RVFV RNA，包括 1 名尸检时因肝坏死和其他终末器官损伤而死亡。2018 年 6 月至 8 月期间，感染了 RVFV 的人类入组，他们都居住在城市地区或附近。人类和牛 RVFV 序列的系统发育分析表明，大多数聚集在谱系 B 上，这是之前在东非描述的谱系。在牛中也发现了与安哥拉谱系聚集的谱系 E 菌株。结论 我们提供的证据表明，坦桑尼亚北部奶牛中明显较小的 RVFV 爆发与人类并发的严重和致命感染有关。我们的研究结果强调了动物流行性 RVFV 传播的未知规模和多样性，包括城市地区附近和内部。