Serological and molecular evidence of an endemic presence of mpox and associated risk factors in semi-rural areas of southern Cameroon

The mpox epidemic in Africa is maintained by zoonotic spill-over events and sustained human-to-human transmissions. Our objective in this work was to conduct serological and molecular surveys on the circulation of mpox in Southern Cameroon and associated risk factors. To that end, we conducted cross-sectional surveys and a case investigation between May and August 2025. We screened samples for mpox antibodies and DNA and sequenced PCR-positive samples. Overall, we included 1072 persons (523 women and 549 men) with a median age of 30 years. A total of 122/1072 (11.4%) samples were mpox antibody positive. Seroprevalence was higher in samples collected in August than in May 2025. Risk factors significantly associated with positivity to mpox antibodies were age above 66 years, being widowed, having been bitten at least once by a wild animal and having contact with wildlife. Of the five samples from case investigation, only the index case was PCR-positive (H, 52 years old), confirmed as mpox clade Ia by sequencing (group I). In serology, 2 of the 5 samples of the household (index case and his 13-year-old son) were mpox antibody positive. This pilot work suggests endemic circulation of mpox in the studied semi-rural districts of southern Cameroon.