The Republic of Congo (RoC) declared a chikungunya (CHIK) outbreak on 9 February 2019. We conducted a ONE-Human-Animal HEALTH epidemiological, virological and entomological investigation. Methods: We collected national surveillance and epidemiological data. CHIK diagnosis was based on RT-PCR and CHIKV-specific antibodies. Full CHIKV genome sequences were obtained by Sanger and MinION approaches and Bayesian tree phylogenetic analysis was performed. Mosquito larvae and 215 adult mosquitoes were collected in different villages of Kouilou and Pointe-Noire districts and estimates of Aedes (Ae.) mosquitos’ CHIKV-infectious bites obtained. We found two new CHIKV sequences of the East/Central/South African (ECSA) lineage, clustering with the recent enzootic sub-clade 2, showing the A226V mutation. The RoC 2019 CHIKV strain has two novel mutations, E2-T126M and E2-H351N. Phylogenetic suggests a common origin from 2016 Angola strain, from which it diverged around 1989 (95% HPD 1985–1994). The infectious bite pattern was similar for 2017, 2018 and early 2019. One Ae. albopictus pool was RT-PCR positive. The 2019 RoC CHIKV strain seems to be recently introduced or be endemic in sylvatic cycle. Distinct from the contemporary Indian CHIKV isolates and in contrast to the original Central-African strains (transmitted by Ae. aegypti), it carries the A226V mutation, indicating an independent adaptive mutation in response to vector replacement (Ae. albopictus vs Ae. aegypti).

中文翻译：

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刚果共和国基孔肯雅热疫情，2019年-南北多学科工作组调查的流行病学，病毒学和昆虫学发现。

刚果共和国（RoC）于2019年2月9日宣布爆发基孔肯雅热（CHIK）。我们进行了一次人畜健康的流行病学，病毒学和昆虫学调查。方法： 我们收集了国家监测和流行病学数据。CHIK诊断基于RT-PCR和CHIKV特异性抗体。通过Sanger和MinION方法获得了完整的CHIKV基因组序列，并进行了贝叶斯树系统发育分析。在Kouilou和Pointe-Noire地区的不同村庄收集了蚊子幼虫和215只成年蚊子，并估计了伊蚊（Aedes）的CHIKV感染叮咬。我们发现了东部/中部/南非（ECSA）谱系的两个新的CHIKV序列，它们与最近的昆虫亚进化支2聚集，显示了A226V突变。RoC 2019 CHIKV菌株具有两个新突变E2-T126M和E2-H351N。系统发育学表明，其起源于2016年的安哥拉菌株，在1989年左右与之分离（95％的HPD 1985–1994）。2017年的传染性叮咬模式相似，阂。白化病库为RT-PCR阳性。2019 RoC CHIKV菌株似乎是最近引入的或在sylvatic周期中是地方性的。从当代印度CHIKV分离并在对比原始中部非洲株（通过发送的不同的埃及伊蚊），它携带A226V突变，表明响应于向量替换一个独立的适应性突变（白纹伊蚊VS埃及伊蚊） 。