Molecular and morphologic characterization of Trichuris trichiura infecting free-roaming African vervets (Chlorocebus aethiops sabaeus) on the Caribbean Island of St. Kitts

Abstract

Human trichuriasis is an important disease caused by the soil-transmitted helminth Trichuris trichiura, which typically affects human populations in low socioeconomic situations. Natural hosts of T. trichiura include humans and certain non-human primates (NHPs), giving rise to concerns that NHPs could serve as zoonotic reservoirs of T. trichiura in locations where humans and NHPs exist in proximity. Free-roaming vervets (Chlorocebus aethiops sabaeus), introduced from Africa to the Caribbean island of St. Kitts represent cause for concern given their propensity to roam within urban environments. To investigate the potential role of vervets as reservoirs of human trichuriasis, we sought to genotype T. trichiura collected from St. Kitts vervets and compare their genotypes to those observed previously from humans and other primates. Thirty-two adult T. trichiura and 17 fecal samples containing T. trichiura eggs collected from St. Kitts vervets were subjected to molecular analysis, involving deep sequencing of PCR amplicons targeting the 18S ribosomal DNA hypervariable regions I and IV (HVR-I & HVR-IV), and a fragment of the mitochondrial genome spanning part of the small subunit ribosomal RNA gene, the valine transfer RNA gene, and the large subunit rDNA. Morphometric analysis of adult worms demonstrated consistency with previous studies on T. trichiura from primate hosts. Phylogenetic analysis showed that T. trichiura from St. Kitts vervets belong to a clade that had recently been implicated in human infections and had also been detected in ancient human latrines in Europe. This observation supports that St. Kitts vervets might represent reservoirs for human infection. Author summary: This paper seeks to start to answer the question of whether vervet monkeys on the Caribbean island of St. Kitts can transmit Trichuris trichiura to the human population. This is especially of interest since we know that some humans on the island are affected by trichuriasis, and that the monkeys co-occur with the human population in time and space. This overlap may afford an opportunity for zoonotic transmission to occur. To investigate this, we utilized a series of PCR reactions targeting several Trichuris genes and amplified these genes from Trichuris worms and eggs isolated from this vervet population. We sequenced the amplicons using next generation sequencing technology and compared the genotypes identified to those seen previously in humans and other primates. We found that the types of T. trichiura in St Kitts vervets genetically matched some types observed previously in humans, supporting that the monkeys could serve as a reservoir for human infections. More evidence will need to be gathered to assess the human-infecting potential of T. trichiura from St Kitts vervets, including the collection of T. trichiura from humans on St. Kitts to ascertain if those genotypes are a match for those described from vervets.

Original publication: PLOS Neglected Tropical Diseases (2026-07-16). Source. Source DOI: 10.1371/journal.pntd.0014539.