Abstract
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).
Highlights
IntroductionRe-emerging zoonotic infectious diseases cause much human suffering worldwide, in West and Central Africa where major arbovirosis and other zoonotic epidemics keep occurring
Re-emerging zoonotic infectious diseases cause much human suffering worldwide, in West and Central Africa where major arbovirosis and other zoonotic epidemics keep occurring.The recent Ebola virus disease (EVD) epidemics in West Africa (2013–2016) and in the DemocraticRepublic of Congo (DRC) (2018–2020) highlighted that, once an infectious disease takes hold locally, the region and the rest of the world is put at risk [1,2]
Two near complete chikungunya virus (CHIKV) genome sequences were obtained from serum samples of two acutely infected women, one living in Tchali, Pointe Noire, collected on the 20 of March (n. 1, 63 years old) and the other living in Nkoungou, Pointe Noire, collected on the 5 of March (n. 2, age not available)
Summary
Re-emerging zoonotic infectious diseases cause much human suffering worldwide, in West and Central Africa where major arbovirosis and other zoonotic epidemics keep occurring. Republic of Congo (DRC) (2018–2020) highlighted that, once an infectious disease takes hold locally, the region and the rest of the world is put at risk [1,2]. This stresses the need of an effective north-south cooperation and of a ONE-HEALTH approach including human, environmental and animal health sectors, to effectively address recurrent and emergent zoonotic threats. CHIKV isolates from the 2007 Gabon outbreak belonged to the ECSA lineage with the E1-A226V mutation [10], which increases the competence of Ae. albopictus as disease vector [11,12]. PANDORA-ID-NET consortium (https://www.pandora-id.net/), by The Congolese Foundation for Medical Research (FCRM) and by The National Public Health Laboratory (LNSP)
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