Cross-infection of <Ascaris> spp. in humans and pigs from a Guarani indigenous village in southern Brazil

BackgroundAscaris lumbricoides and Ascaris suum are nematode parasites that infect millions of people and pigs worldwide, respectively. Reports of cross-infection between the two host species has stimulated molecular epidemiological studies of the Ascaris genus. In this study, we evaluated the dynamics of Ascaris transmission between Guarani indigenous schoolchildren, pigs, and the environment of a village in the state of Parana, southern Brazil. Methodology/Principal findingsParasitological and molecular analyses of fecal samples from humans and pigs, and soil samples from the village were carried out. Eggs of Ascaris spp. were observed in 8.4% (7/83) of human samples, 44.4% (8/18) of pig samples, and 8.9% (6/68) of soil samples. PCR amplification of the ITS-1 locus of the rDNA gene in samples that were positive in the parasitological examination revealed cross-infection by the two species, A. lumbricoides and A. suum, in human and swine hosts. The soil, which was contaminated by both human and swine feces, also contained eggs of the two Ascaris species, thus constituting a source of Ascaris infection for both hosts. DNA from both nematode species, individually and mixed, was detected in samples from both hosts and the soil. Conclusions/SignificanceThe results of this study indicate that more effective control measures, aimed at the correct disposal of both human and animal feces, should be implemented. Author SummaryDespite the control measures implemented in Brazilian Indigenous Lands, the prevalence of intestinal parasites continues to vary from moderate to high in its inhabitants. On the other hand, the number of indigenous people residing in Brazil has been increasing in last decades, including the South region of the country, where a much smaller proportion of indigenous people reside compared to the North region. Ascaris lumbricoides and Ascaris suum are the most prevalent helminth parasites in humans and pigs, respectively. The possibility of cross-infection by Ascaris spp. between humans and pigs has been analyzed in order to propose more effective control measures. In this research, we use parasitological and molecular methods to verify the presence of these parasites in fecal samples from schoolchildren and pigs, in addition to soil samples, from a Guarani indigenous village in the state of Parana, southern Brazil. Genetic material from both individual and associated nematode species was detected in host and soil samples, indicating cross-transmission in these populations. Control measures aimed at the correct disposal of human and animal feces must be implemented in order to minimize damage to health and prevent new infections.