Insights into the molecular systematics of Trichuris infecting captive primates based on mitochondrial DNA analysis

Nematodes belonging to the Trichuris genus are prevalent soil-transmitted helminths with a worldwide distribution in mammals, while humans are mainly affected in areas with insufficient sanitation such as in Africa, Asia and South America. Traditionally, whipworms infecting primates are referred to Trichuris trichiura, but recent molecular and morphological evidence suggests that more than one species may be able to infect humans and non-human primates. Here, we analyzed the genetic diversity and phylogeny of Trichuris infecting five different non-human primate species kept in captivity using sequencing of three mitochondrial genes (cox1, rrnL and cob). Phylogenetic analyses of both single and concatenated datasets suggested the presence of two main evolutionary lineages and several highly supported clades likely existing as separate taxa. The first lineage included Trichuris infecting the mantled guereza (Colobus guereza kikuyensis), the chacma baboon (Papio ursinus) and the green monkeys (Chlorocebus spp.), clustering together with Trichuris suis; the second lineage included Trichuris infecting the Japanese macaque (Macaca fuscata) and the hamadryas baboon (Papio hamadryas), clustering together with Trichuris spp. infecting humans. These results were supported by the genetic distance between samples, which suggested that at least two taxa are able to infect macaques, baboons and humans. The present study improves our understanding of the taxonomy and evolutionary relationships among Trichuris spp. infecting primates. It moreover suggests that multiple Trichuris spp. may circulate among host species and that Trichuris in non human primates (NHPs) may be zoonotic. Further studies are important to better understand the epidemiology of Trichuris in primates and for implementing appropriate control and/or conservation measures.