Molecular analysis of human- and pig-derivedAscarisin Honduras

Abstract

Ascaris sp. is a soil-transmitted helminth (STH) significantly affecting the health of human and swine populations. Health inequities and poverty, with resulting deficiencies in water, sanitation and hygiene, are directly associated with Ascaris lumbricoides prevalence in humans. Resource constraints also lead to small-scale livestock production under unsanitary conditions. Free-ranging pigs, for instance, are exposed to a number of infectious agents, among which Ascaris suum is one of the most common. Under these conditions, close proximity between people and pigs can result in cross-contamination; that is, pigs harbouring human Ascaris and vice versa. Moreover, the potential interbreeding between these two Ascaris species has been demonstrated. The present study analysed Ascaris worms obtained from children and pigs in Honduras. Adult worms were collected from stool samples of children after pharmacological treatment, and from pigs' intestines after slaughter for commercial purposes at a local abattoir. A nuclear ribosomal internal transcribed spacer (ITS) region was amplified by polymerase chain reaction (PCR) and digested with a restriction enzyme in order to separate putative human- and pig-derived Ascaris isolates. PCR products were also sequenced, and cladograms were constructed. All parasites isolated from children showed the typical human-derived genotype of Ascaris, whereas 91% of parasites from pigs showed the expected pig-derived genotype. Cross-infections between hosts were not demonstrated in this study. Nine per cent of pig-derived worms showed a restriction band pattern highly suggestive of a hybrid human-pig Ascaris genotype. These results contribute to the understanding of ascariasis epidemiology and its zoonotic potential in a highly endemic region.

Absence of mutations associated with resistance to benzimidazole in the beta-tubulin gene of Ascaris suum

“…Worms were thoroughly washed with a saline solution and stored at room temperature in 70% (v/v) ethanol until further use. DNA was purified using a previously described method 13 . Two separate PCR reactions were carried out to analyze three codons of the β-tubulin gene.…”

“…Of the 50 adult Ascaris worms collected from 17 pigs, six (12%) had previously been classified as putative hybrids (or heterozygotes) between pig-and human-derived Ascaris through a PCR-RFLP approach of the nuclear internal transcribed spacer (ITS) ribosomal region 13 . The remaining 46 worms were classified as pig-derived Ascaris (Ascaris suum).…”

Genotyping of Ascaris spp. infecting humans and pigs in Italy, Slovakia and Colombia

“…Previous studies focused on endemic countries reported diverse patterns of genotypes, such as high level of cross-infections with A. suum in humans in China (Zhou et al, 2012); 9% of hybrids in pig-derived worms in Honduras (Palma et al, 2019); the absence of crosstransmission and the presence of A. lumbricoides in people and A. suum in pigs in Ecuador and Honduras (Sparks et al, 2015); very low percentage of A. suum in human samples from Zanzibar (Sparks et al, 2015), and pig-associated genotype in all samples from pigs and mainly human-associated genotype in samples from humans in Thailand, the Lao PDR, and Myanmar (Sadaow et al, 2018). The latter pattern is similar to the genotype distribution found in the present study in Colombia, here representative for the endemic countries.…”

“…Therefore, several studies have been conducted in countries such as Italy, Honduras, Brazil, Ecuador, Zanzibar, Myanmar, Thailand, and China (Cavallero et al, 2013;Monteiro et al, 2019;Palma et al, 2019;Sadaow et al, 2018;Sparks et al, 2015;Zhou et al, 2018), aiming to evaluate the amount and nature of genetic diversity of Ascaris spp. circulating in humans and pigs, and to explore their zoonotic potential and cross-transmission.…”

Mobility and feeding habits of semi-confined domestic pig groups in a rural locality endemic to cysticercosis

“…In contrast, rustically reared pigs are housed in a pigsty, usually a roofed, dirtfloor structure; other less well-delimited areas, with or without walls, are sometimes used as pigsties. Pig feed may consist of grains and food waste, but rustically reared pigs obtain most of their diet by foraging through the village or its surroundings (Linares-Ibáñez et al, 2011;Thomas et al, 2013;Palma et al, 2017).…”