Phylogenetic Evidence That Two Distinct Trichuris Genotypes Infect both Humans and Non-Human Primates

Abstract

Although there has been extensive debate about whether Trichuris suis and Trichuris trichiura are separate species, only one species of the whipworm T. trichiura has been considered to infect humans and non-human primates. In order to investigate potential cross infection of Trichuris sp. between baboons and humans in the Cape Peninsula, South Africa, we sequenced the ITS1-5.8S-ITS2 region of adult Trichuris sp. worms isolated from five baboons from three different troops, namely the Cape Peninsula troop, Groot Olifantsbos troop and Da Gama Park troop. This region was also sequenced from T. trichiura isolated from a human patient from central Africa (Cameroon) for comparison. By combining this dataset with Genbank records for Trichuris isolated from other humans, non-human primates and pigs from several different countries in Europe, Asia, and Africa, we confirmed the identification of two distinct Trichuris genotypes that infect primates. Trichuris sp. isolated from the Peninsula baboons fell into two distinct clades that were found to also infect human patients from Cameroon, Uganda and Jamaica (named the CP-GOB clade) and China, Thailand, the Czech Republic, and Uganda (named the DG clade), respectively. The divergence of these Trichuris clades is ancient and precedes the diversification of T. suis which clustered closely to the CP-GOB clade. The identification of two distinct Trichuris genotypes infecting both humans and non-human primates is important for the ongoing treatment of Trichuris which is estimated to infect 600 million people worldwide. Currently baboons in the Cape Peninsula, which visit urban areas, provide a constant risk of infection to local communities. A reduction in spatial overlap between humans and baboons is thus an important measure to reduce both cross-transmission and zoonoses of helminthes in Southern Africa.

Molecular Testing for Clinical Diagnosis and Epidemiological Investigations of Intestinal Parasitic Infections

“…Combining ITS1-5.8S-ITS2 sequences from adult Trichuris sp. worms isolated from baboons with GenBank records for Trichuris isolated from other humans, other nonhuman primates, and pigs revealed two distinct Trichuris genotypes separated from T. suis infect- ing baboons and human patients from Cameroon (315). The zoonotic potential of T. suis and different Trichuris genotypes is yet not fully understood, and further studies on these sympatric Trichuris infections are needed.…”

Genetic heterogeneity and phylogeny of Trichuris spp. from captive non-human primates based on ribosomal DNA sequence data

“…c o m / l o c a t e / m e e g i d et al, 2012), species boundary is not easy to define. In addition, recent molecular studies have described two distinct Trichuris genotypes infecting both humans and NHP (Ravasi et al, 2012;Liu et al, 2013), without clearly defining whether Trichuris sp. reported in captive and wild NHP are one or more different species.…”

“…Trichuriasis is considered a Neglected Tropical Disease (NTD) by WHO, widespread in tropical and sub-tropical regions, especially in developing countries (Bethony et al, 2011;Hotez et al, 2012). The genus Trichuris includes around one hundred recognized species (Yamaguti, 1961), but only three, Trichuris trichiura, Trichuris suis and Trichuris vulpis, are considered zoonotic, representing a potential threat to human health (Ravasi et al, 2012). However, due to morphological and biological similarities, traditional specific identification based on morphology of both eggs and adult worms is not reliable and molecular tools would be highly recommended for this purpose.…”

Ecology and Epidemiology of Nematode Infection in Japanese Macaques:

“…The conclusion was that nonhuman primates were not a reservoir for human infection and therefore did not represent an important risk factor for human oesophagostomiasis (van Lieshout et al 2005). Nonetheless, studies clearly demonstrating cases in which human and nonhuman primates do indeed pose an infection risk for each other are beginning to surface (Ravasi et al 2012;Ghai et al 2014), so models capable of capturing transmission dynamics incorporating human and multiple nonhuman primate hosts remain necessary.…”