Molecular epidemiology of recurrent zoonotic transmission of mpox virus in West Africa.

Nigeria and Cameroon reported their first mpox cases in over three decades in 2017 and 2018 respectively. The outbreak in Nigeria is recognised as an ongoing human epidemic. However, owing to sparse surveillance and genomic data, it is not known whether the increase in cases in Cameroon is driven by zoonotic or sustained human transmission. Notably, the frequency of zoonotic transmission remains unknown in both Cameroon and Nigeria. To address these uncertainties, we investigated the zoonotic transmission dynamics of the mpox virus (MPXV) in Cameroon and Nigeria, with a particular focus on the border regions. We show that in these regions mpox cases are still driven by zoonotic transmission of a newly identified Clade IIb.1. We identify two distinct zoonotic lineages that circulate across the Nigeria-Cameroon border, with evidence of recent and historic cross border dissemination. Our findings support that the complex cross-border forest ecosystems likely hosts shared animal populations that drive cross-border viral spread, which is likely where extant Clade IIb originated. We identify that the closest zoonotic outgroup to the human epidemic circulated in southern Nigeria in October 2013. We also show that the zoonotic precursor lineage circulated in an animal population in southern Nigeria for more than 45 years. This supports findings that southern Nigeria was the origin of the human epidemic. Our study highlights the ongoing MPXV zoonotic transmission in Cameroon and Nigeria, underscoring the continuous risk of MPXV (re)emergence.

Concurrent Clade I and Clade II Monkeypox Virus Circulation, Cameroon, 1979-2022.

During 1979-2022, Cameroon recorded 32 laboratory-confirmed mpox cases among 137 suspected mpox cases identified by the national surveillance network. The highest positivity rate occurred in 2022, indicating potential mpox re-emergence in Cameroon. Both clade I (n = 12) and clade II (n = 18) monkeypox virus (MPXV) were reported, a unique feature of mpox in Cameroon. The overall case-fatality ratio of 2.2% was associated with clade II. We found mpox occurred only in the forested southern part of the country, and MPXV phylogeographic structure revealed a clear geographic separation among concurrent circulating clades. Clade I originated from eastern regions close to neighboring mpox-endemic countries in Central Africa; clade II was prevalent in western regions close to West Africa. Our findings suggest that MPXV re-emerged after a 30-year lapse and might arise from different viral reservoirs unique to ecosystems in eastern and western rainforests of Cameroon.

COVID-19 in a region of Cameroon hit by armed conflict.

Introduction: the emergence of more transmissible SARS-CoV-2 variants like Delta and Omicron have triggered the next wave of COVID-19 in many parts of the world. Here we report a surge in COVID-19 cases and deaths in the Northwest (NW) Region of Cameroon, which is plagued with low immunization coverage and armed conflict. Methods: a cross-sectional study was conducted in September 2021 and data on COVID-19 cases and vaccination were reviewed from the Ministry of Health database from January 1st, 2020 to September 4th, 2021. The security situation of the region was obtained from the districts and regional health managers. Data were analyzed with MS Excel and results presented as trends and proportions. Results: since the onset of COVID-19 pandemic, there is an increasing prevalence in cases in the NW. Between epidemiological week 34-35 of 2021, there was a surge in COVID-19 cases in the NW. More than 70% of all COVID-19 related deaths reported in the country during epidemiological week-35 were recorded in this region. Despite this high mortality, COVID-19 vaccine uptake remains very low in the region. Indeed, just 0.6% of the 962,036-target population 18-years and above are fully immunized after 6-months of vaccination. Conclusion: though the country´s epi-curve does not suggest a third wave currently, the NW is experiencing a steady COVID-19 case surge amid insecurity and the circulation of the Delta variant. There is therefore a need to adopt innovative strategies to improve immunization and strengthen other SARS-CoV-2 preventive measures in this region.