Genetic diversity of Ascaris spp. infecting humans and pigs in distinct Brazilian regions, as revealed by mitochondrial DNA

Abstract

In this study, we assessed the genetic diversity of Ascaris lumbricoides / Ascaris suum circulating in humans and pigs, exploring potential zoonotic cycles in endemic areas in Brazil. We carried out cross-sectional surveys in four municipalities: Santa Isabel do Rio Negro (SIRN-AM) (n = 328); Nossa Senhora de Nazaré (NSN-PI) and Teresina (TER-PI) (n = 605 and n = 297, respectively); and Cachoeiras de Macacu (CAM-RJ) (n = 543). We also studied 61 fecal samples/adult worms obtained from pigs (n = 53 in NSN-PI and n = 8 in TER-PI). A ~450 bp fragment of the Ascaris cytochrome c oxidase subunit 1 ( cox 1) and ~400 bp of the NADH dehydrogenase subunit 1 ( nad 1) were amplified and sequenced. Maximum-likelihood (ML) tree and Median-joining (MJ) haplotype network analyses were performed. We also performed scanning electron micrographs of adult specimens. Positivity rates were 93/328 (28.4%) in SIRN-AM, 6/297 (2.0%) in TER-PI, 0/605 (0%) in NSN-PI, and 6/543 (1.1%) in CAM-RJ. In NSN-PI it reached 11/53 (20.7%) in pigs. The MJ network based on cox 1 locus (383 bp) revealed three main clusters, one centered around haplotypes H01/H28/H32 and the other around H07/H11. The cox 1 haplotypes had a heterogeneous distribution, showing no pattern by geographic region, and high haplotype diversity. The ML trees based on cox 1 and nad 1 loci showed a similar topology with each other, and with the haplotype networks. Three distinct clusters were observed. Sequences of cox 1 and nad 1 from humans and animals were distributed throughout the tree and it was not possible to differentiate specimens of human and swine origin. Ascaris populations obtained from humans and swine in different Brazilian regions are not discriminable through the genetic markers used, which indicates the potential for zoonotic transmission and the need for better control of these infections in swine herds, mainly when created in a peridomestic environment.

Molecular evidence of hybridization between pig and human Ascaris indicates an interbred species complex infecting humans

“…Population genetic studies of A. lumbricoides have drawn varying conclusions about whether zoonotic transmission is frequent ( Anderson and Jaenike, 1997 ; Dutto and Petrosillo, 2013 ; Nejsum et al, 2012 ; Nejsum et al, 2005a ). Some studies have shown that cross-species transmission occurs between pigs and humans living in close proximity ( Anderson, 1995 ; Betson et al, 2014 ; Miller et al, 2015 ; Monteiro et al, 2019 ; Nejsum et al, 2005b ; Peng and Criscione, 2012 ; Sadaow et al, 2018 ; Takata, 1951 ; Zhu et al, 1999 ). This is especially common in non-endemic regions, probably because zoonotic transmission is less likely to be identified in areas where human-to-human transmission is common.…”

Immune serum–activated human macrophages coordinate with eosinophils to immobilize Ascaris suum larvae

“…Further insight for the identification of correlates of protection could be provided by the study of humoral and cellular mechanisms that confer protection in animal models A. suum is the infectious agent of porcine ascariasis, which substantial and is closely related to the human helminth A. lumbricoides. Both parasites show striking similarities in their morphology, biology and genetics with both exhibiting anthropozoonotic potential (9)(10)(11). Accordingly, it has been suggested that the two parasites actually belong to the same species (12), with A. suum representing an excellent model to study the common human nematode.…”

Saúde-Doença E Morte Em Indígenas: Reflexões Do Suicídio

“…Escolheu-se aleatoriamente dois grupos de parasitos, Ascaris lumbricoides e os ancilostomídeos, para questionar especifi camente sobre seus ciclos de vida e formas No entanto, faz-se imprescindível enfatizar sobre o potencial zoonótico de Ascaris sp., principalmente relacionando aos cuidados na criação de suínos (MONTEIRO et al, 2019). À medida que conhecem sobre esse parasito, promovem a redução na transmissão, reinfecção e incentivam a família a comportamentos saudáveis.…”