Detection of DNA of filariae closely related to Mansonella perstansin faecal samples from wild non-human primates from Cameroon and Gabon

Background The Onchocercidae is a family of filarial nematodes with several species of medical or veterinary importance. Microfilariae are found in the blood and/or the dermis and are usually diagnosed in humans by microscopy examination of a blood sample or skin biopsy. The main objectives of this study were to evaluate whether filariae DNA can be detected in faecal samples of wild non-human primates (NHPs), whether the detected parasites were closely related to those infecting humans and whether filarial DNA detection in faeces is associated with co-infections with nematodes (Oesophagostumumsp. andNecator sp.) known to cause blood loss while feeding on the host intestinal mucosa. Methods A total of 315 faecal samples from 6 species of NHPs from Cameroon and Gabon were analysed. PCRs targeted DNA fragments ofcox1 and12SrDNA genes, to detect the presence of filariae, and the internal transcribed spacer 2 (ITS2), to detect the presence ofOesophagostomumsp. andNecatorsp. infections. Results Among the 315 samples analysed, 121 produced sequences with > 90% homology with Onchocercidae reference sequences. However, 63% of the12SrDNA and 78% of thecox1 gene sequences were exploitable for phylogenetic analyses and the amplification of the12SrDNA gene showed less discriminating power than the amplification of thecox1 fragment. Phylogenetic analyses showed that thecox1 sequences obtained from five chimpanzee DNA faecal samples from Gabon and two from Cameroon cluster together withMansonella perstanswith high bootstrap support. Most of the remaining sequences clustered together within the genusMansonella, but the species could not be resolved. Among the NHP species investigated, a significant association between filarial DNA detection andOesophagostomumsp. andNecatorsp. infection was observed only in gorillas. Conclusions To our knowledge, this is the first study reporting DNA fromMansonellaspp. in faecal samples. Our results raise questions about the diversity and abundance of these parasites in wildlife, their role as sylvatic reservoirs and their potential for zoonotic transmission. Future studies should focus on detecting variants circulating in both human and NHPs, and improve the molecular information to resolve or support taxonomy classification based on morphological descriptions