Toxocariasis, caused by Toxocara spp. nematodes, is among the top 5 neglected parasitic diseases worldwide; however, no comprehensive study to date has serologically compared infections in people and their dogs and environmentally contaminated soil or sand of mainland and island locations. Accordingly, this study aimed to assess the seroprevalence of anti- Toxocara antibodies in traditional human seashore populations, the presence of eggs in dogs' feces and hair, and the presence of eggs in environmental samples from islands compared to the adjacent mainland of southern Brazil. Overall, 212/328 (64.6%) people were positive for Toxocara spp. antibodies, including 125/190 (65.8%) island and 87/138 (63.0%) mainland residents. For dog samples, 12/115 (10.43%) were positive for the presence of Toxocara spp. eggs, all from dogs living in islands, and 22/104 (21.15%) dog hair samples contained eggs of Toxocara spp. Environmental contamination with Toxocara spp. eggs was observed in 50/130 (38.46%) samples from all sampled sites. No significant association was found between risk factors (age, sex, educational level, monthly income, owning dogs or cats, ingestion of treated water, and consumption of raw or uncooked meat) and Toxocara spp. seropositivity. The present study is the first concurrent report on people, their dogs, and environmental contamination of Toxocara spp. The high prevalence we observed in the seashore populations of both in island and mainland areas may be caused by exposure to contaminated sand and climatic factors favoring frequent exposure to Toxocara spp. In conclusion, seashore lifestyle and living conditions of both island and mainland areas may have predisposed higher contact with infected pets and contaminated soil, favoring the high prevalence of toxocariasis.

The present study aimed to experimentally assess Nile tilapia as potential paratenic host of Toxocara spp. A total of 15 Nile tilapia (Oreochromis niloticus) were fed with 300 embryonated Toxocara canis eggs by oral gavage, while five others of the control group received distilled water. The fish were individually analyzed at 16, 24, 48, 72, and 240 h after inoculation. Water contamination was assessed, and tissue migration by liver, gastrointestinal tract (GIT), eyes, and central nervous system. A murine model was used as the paratenic host for egg infectivity assessment. Eggs and larvae were found in plastic tank water and fish GIT, ranging from 23 to 86% per fish. Eggs and larvae were recovered from the tank water (76.3%) and fish GIT (23.7%). The counting of eggs and larvae observed was negatively correlated with number of eggs and larvae in the water tank (rho = −0.698, p = 0.003). Shedding of embryonated eggs was first detected at 16 and up to 240 h, with significant egg and larvae yield decrease on water-shedding (p = 0.001) and in the GIT (p = 0.007). Although no T. canis larva was recovered in fish tissues, egg infectivity after fish GIT transit was experimentally confirmed by mice assessment. In conclusion, despite shedding viable embryonated eggs through the gastrointestinal tract, tilapias may not play a role as a suitable paratenic hosts for Toxocara spp., posing low risk of zoonotic transmission by fish meat consumption.

Strongyloides stercoralis, a pathogenic roundworm, is considered endemic in several tropical and subtropical areas worldwide. Indigenous populations have the highest soil-transmitted helminthiases-related mortality rates, but the prevalence and risk factors associated with S. stercoralis in Brazilian indigenous populations have not been established. Thus, the present study aimed to assess the seroprevalence and associated risk factors for S. stercoralis in indigenous communities and the healthcare professionals serving them in Brazil. Indigenous populations living in nine communities and healthcare professionals were tested for anti- S. stercoralis antibodies by ELISA. A questionnaire was used to assess socio-epidemiological information. Associated risk factors for seropositivity were tested by chi-square or Fisher’s exact tests, using bivariate analyses and multivariate logistic regression. Overall, 174/463 (37.6%; CI 95%: 33.3–42.1) indigenous persons and 77/147 (52.4%; 95% CI: 44.3–60.3) healthcare professionals were seropositive for anti- S. stercoralis antibodies. Seropositivity among the two groups was statistically significant (p = 0.0016; OR = 0.547; 95% CI: 0.376–0.796) and revealed that healthcare professionals were 1.83 times more likely to be seropositive. The multivariate analysis showed that being male or being adult were also risk factors, while having a septic tank as a sanitary facility represented a protective factor for S. stercoralis exposure in indigenous persons. None of the variables evaluated were associated with S. stercoralis exposure in the professional group. The study herein has reported a high seroprevalence to Strongyloides stercoralis in indigenous communities of Brazil and healthcare professionals, warning for potential public health concerns of strongyloidiasis in such populations.

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