Poxvirus and Rabies Branch, Centers for Disease Control and Prevention, Atlanta, Georgia, USA.
Epidemic Intelligence Service, Centers for Disease Control and Prevention, Atlanta, Georgia, USA.
J Infect Dis. 2022 Apr 19;225(8):1367-1376. doi: 10.1093/infdis/jiaa559.
The largest West African monkeypox outbreak began September 2017, in Nigeria. Four individuals traveling from Nigeria to the United Kingdom (n = 2), Israel (n = 1), and Singapore (n = 1) became the first human monkeypox cases exported from Africa, and a related nosocomial transmission event in the United Kingdom became the first confirmed human-to-human monkeypox transmission event outside of Africa.
Epidemiological and molecular data for exported and Nigerian cases were analyzed jointly to better understand the exportations in the temporal and geographic context of the outbreak.
Isolates from all travelers and a Bayelsa case shared a most recent common ancestor and traveled to Bayelsa, Delta, or Rivers states. Genetic variation for this cluster was lower than would be expected from a random sampling of genomes from this outbreak, but data did not support direct links between travelers.
Monophyly of exportation cases and the Bayelsa sample, along with the intermediate levels of genetic variation, suggest a small pool of related isolates is the likely source for the exported infections. This may be the result of the level of genetic variation present in monkeypox isolates circulating within the contiguous region of Bayelsa, Delta, and Rivers states, or another more restricted, yet unidentified source pool.
2017 年 9 月，尼日利亚爆发了西半球最大规模的猴痘疫情。有 4 名曾前往尼日利亚的旅行者分别前往英国（2 例）、以色列（1 例）和新加坡（1 例），他们成为首批从非洲输出的人类猴痘病例，而英国的一起相关医院内传播事件则成为非洲以外首例经证实的人际间猴痘传播事件。
对输出病例和尼日利亚病例的流行病学和分子数据进行联合分析，以便更好地在疫情的时间和地理背景下了解这些输出病例。
所有旅行者和一例贝宁城病例的分离株拥有一个最近的共同祖先，并前往贝宁城、三角洲或里弗斯州。该聚类的遗传变异低于从此次疫情中随机抽样基因组的预期水平，但数据并不支持旅行者之间存在直接联系。
输出病例和贝宁城样本的单系性，以及中等水平的遗传变异，表明相关分离株的小池可能是这些输出感染的来源。这可能是由于贝宁城、三角洲和里弗斯州毗邻地区循环的猴痘分离株中存在的遗传变异水平，或者是另一个更受限但尚未确定的来源池所致。
