How many species of whipworms do we share? Whipworms from man and other primates form two phylogenetic lineages

Abstract

Abstract:The whipworms, i.e. parasitic nematodes of the genus Trichuris Roederer, 1761, infect a variety of mammals. Apparently low diversity of primate-infecting species of Trichuris strongly contrasts with the high number of species described in other mammalian hosts. The present study addresses the diversity of whipworms in captive and free-ranging primates and humans by analysing nuclear (18S rRNA, ITS2) and mitochondrial (cox1) DNA. Phylogenetic analyses revealed that primate whipworms form two independent lineages: (i) the Trichuris trichiura (Linnaeus, 1771) clade comprised of genetically almost identical whipworms from human and other primates, which suggests the ability of T. trichiura to infect a broader range of primates; (ii) a clade containing primarily Trichuris suis Schrank, 1788, where isolates from human and various primates formed a sister group to isolates from pigs; the former isolates thus may represent of more species of Trichuris in primates including humans. The analysis of cox1 has shown the polyphyly of the genera Trichuris and Capillaria, Zeder, 1800. High sequence similarity of the T. trichiura isolates from humans and other primates suggests their zoonotic potential, although the extent of transmission between human and other non-human primates remains questionable and requires further study.

Two new species of Trichuris (Nematoda: Trichuridae) collected from endemic murines of Indonesia

“…Actually, occurrence of such host-shift events in Trichuris evolution has been suggested by molecular phylogenetic studies (cf. Callejón et al, 2015;Doležalová et al, 2015).…”

Prospects on the Application of DNA Barcoding on Soil-Transmitted Helminths in Children

“…60 However, in addition to the difficulty in obtaining adult worms from animals (e.g., primates), well-preserved mature nematodes are required for morphological study. 61 Hence, misidentification of the parasitic worm could result in misleading zoonotic potential of that particular parasitic worm (e.g., whipworms 61 ). Fortunately, DNA barcoding may overcome this taxonomic impediment (i.e., cryptic species).…”

“…25 However, COI gene is still not considered suitable to address phylogenetic relationships among Trichuris species because COI analysis revealed that isolates of Capillaria were found in the same clade as Trichuris. 61 This may be due to the lack of Trichuris sequences in the database. 61 For roundworms, 59 Ascaris worms were collected from 4 villages in Unguja (Africa) and the diversity of Ascaris worms based on DNA barcodes was found to be higher in Africa (15 distinct haplotypes in 59 Ascaris worms 65 compared with China [19 distinct haplotypes in 723 Ascaris worms collected from humans and pigs 66 ]).…”

“…61 This may be due to the lack of Trichuris sequences in the database. 61 For roundworms, 59 Ascaris worms were collected from 4 villages in Unguja (Africa) and the diversity of Ascaris worms based on DNA barcodes was found to be higher in Africa (15 distinct haplotypes in 59 Ascaris worms 65 compared with China [19 distinct haplotypes in 723 Ascaris worms collected from humans and pigs 66 ]). Based on DNA barcodes, one Ascaris species was commonly found in both humans and pigs, suggesting the zoonotic potential of Ascaris.…”

“…Despite the growing popularity of DNA barcoding and its reliability in species identification, the study of STHs using DNA barcoding is limited and results in the paucity of STH sequences in the gene bank database, especially T. trichiura. 61 The keywords, "Ancylostoma duodenale," "Ascaris lumbricoides," "Necator americanus," "Trichuris trichiura," and "COI" were used to search for publicly available COI sequences of STHs in two gene banks (i.e., NCBI and BOLD) on November 24, 2016. There were 21 COI sequences of A. duodenale, 65 COI sequences of A. lumbricoides, 64 COI sequences of N. americanus, and 7 COI sequences of T. trichiura available in NCBI, whereas there was only 1 COI sequence of A. duodenale, 1 COI sequence of A. lumbricoides, 1 COI sequence of N. americanus, and no COI sequence of T. trichiura available in the BOLD (►Table 1).…”