Genomic characterization of rare Salmonella enterica serovars in free-ranging African primates from the Democratic Republic of the Congo

Salmonella enterica infections remain a major global public health concern. In tropical ecosystems of Central Africa, where interactions among wildlife, humans, and the environment are frequent, the role of non-human primates (NHPs) in the ecology of Salmonella remains poorly documented. Between December 2023 and July 2025, 630 fecal samples from free-ranging NHPs and 221 human stool samples from adjacent health zones were investigated in the Mabali Forest Reserve, Democratic Republic of the Congo. An integrated approach combining qPCR screening, bacterial isolation, phenotypic identification, detection of the Vi capsular antigen, antimicrobial susceptibility testing, and whole-genome sequencing was used to detect and characterize Salmonella enterica. Among the 569 NHP samples screened, 17 (3%) were positive for Salmonella, yielding seven isolates belonging to three rare serovars, Abadina (predominant), Ipeko, and Hvittingfoss. Antimicrobial susceptibility testing did not identify resistance among the isolates for the agents with applicable interpretive criteria. Although the narG qPCR assay yielded positive results for several isolates, whole-genome sequencing identified all recovered strains as non-typhoidal serovars, highlighting the importance of confirming molecular screening results with genomic approaches when investigating wildlife-associated Salmonella. No S. enterica DNA was detected in human samples. These findings expand current knowledge of the diversity of rare S. enterica serovars detected in free-ranging African NHPs and provide baseline data for future investigations of Salmonella ecology in Central African ecosystems. They also support the value of integrated One Health surveillance combining culture-based methods and whole-genome sequencing to characterize wildlife-associated Salmonella. Clinical Trial Registration Number Not applicable.