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 (cox1) and ~400 bp of the NADH dehydrogenase subunit 1 (nad1) 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 cox1 locus (383 bp) revealed three main clusters, one centered around haplotypes H01/H28/H32 and the other around H07/H11. The cox1 haplotypes had a heterogeneous distribution, showing no pattern by geographic region, and high haplotype diversity. The ML trees based on cox1 and nad1 loci showed a similar topology with each other, and with the haplotype networks. Three distinct clusters were observed. Sequences of cox1 and nad1 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.

Highlights

  • The soil-transmitted helminthes (STH) Ascaris lumbricoides and Ascaris suum are parasites of great importance to human and swine health, respectively [1,2]

  • We assessed the genetic diversity of Ascaris lumbricoides / Ascaris suum circulating in humans and pigs, exploring potential zoonotic cycles in endemic areas in Brazil

  • In order to assess the presence of roundworms, we carried out cross-sectional surveys in four municipalities: Santa Isabel do Rio Negro (SIRN-AM); Nossa Senhora de Nazare (NSN-PI) and Teresina (TER-PI); and Cachoeiras de Macacu (CAM-RJ)

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Summary

Introduction

The soil-transmitted helminthes (STH) Ascaris lumbricoides and Ascaris suum are parasites of great importance to human and swine health, respectively [1,2]. A. lumbricoides can cause potentially serious and fatal disease when high parasitic loads are present. In these cases, ascariasis can be associated with intestinal obstruction and perforation, in addition to the migration of adult worms to the bile duct and other organs [3,4]. Infection by roundworms with high parasitic load is dependent on constant reinfection and continuous exposure to the environment contaminated with fecal matter [7]. In many areas in developing countries, the disease persists as an important public health problem, with a high prevalence rate and infection intensity

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