Prevalence and Genetic Diversity of Parasites in Humans and Pet Dogs in Rural Areas of Los Ríos Region, Southern Chile

Parasitic infections pose a significant global health burden, affecting millions of people worldwide. Despite their importance, studies integrating human and animal parasitology to understand transmission pathways are scarce. This study, conducted between August 2022 and April 2023, aimed to investigate the prevalence of parasites in humans and domestic dogs in the Los Rios Region, southern Chile, and explore the risk factors associated with parasitism. A total of 291 human participants provided fecal and blood samples for parasitological and serological analyses, while 92 fecal samples from owned dogs were analyzed. The detection of intestinal parasites employed microscopy and molecular techniques, including next-generation sequencing (NGS). Anti-<i>Toxocara canis</i> and anti-<i>Echinococcus granulosus</i> antibodies in humans were assessed using ELISA. Socioeconomic surveys explored the risk factors associated with parasitism. The results showed a parasite prevalence of 39% in humans and 40% in dogs. Anti-<i>Toxocara canis</i> IgG antibodies were detected in 28.2% of humans. Zoonotic subtypes of <i>Giardia duodenalis</i> and <i>Blastocystis</i> sp. were identified. Thus, the results of our study indicate a high prevalence of intestinal and extraintestinal parasites in the human population of our region. Furthermore, our findings underscore the significant risk of zoonotic transmission of parasites from companion animals. This study contributes to the understanding of parasite transmission dynamics in southern Chile and has implications for public health policy and practice. The results emphasize the importance of considering the connection between human, animal, and environmental health to develop effective control strategies and mitigate the impact of parasitic infections.