Evaluation of the mpox surveillance system in Cameroon from 2018 to 2022: a laboratory cross-sectional study.

BACKGROUND: Formal assessment of a surveillance system's features and its ability to achieve objectives is crucial for disease control and prevention. Since the implementation of the mpox surveillance system in Cameroon, no evaluation has been conducted. METHODS: In a cross-sectional study, we assessed the performance of the mpox surveillance system in accordance with the Centers for Disease Control and Prevention (CDC) and World Health Organization (WHO) guidelines. We collected mpox surveillance data from 2018 to 2022 and conducted a survey with key stakeholders of the surveillance program. The survey results were summarized. The rates of complete reporting and mpox detection, as well as the time lag between the different stages of surveillance were analyzed using R version 4.1. RESULTS: The mpox detection rate was 21.6% (29/134) over the five years under review. Surveillance indicators revealed that a combination of sample types, including vesicles, crust, and blood, was associated with higher case confirmation. Overall, the mpox surveillance system was effective. Weaknesses in terms of simplicity were identified. Most components of the assessed system failed to meet the timeliness and data quality goals, except for the laboratory component, which was commendable. The lack of a computerized shared database and the system's non-sustainability were a course of concern. CONCLUSIONS: Despite all identified bottlenecks in the mpox surveillance system in Cameroon, it was found to meet it stipulated goals. Recommendations are made for training on surveillance system features, particularly at the facility/field level. Therefore, there is a crucial need to globally improve the mpox surveillance system in Cameroon for better disease control.

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.