Argibay, H. D. | bioRxiv Science

bioRxiv2025

Seroprevalence and risk factors for Toxoplasma gondii transmission in wild, domestic and companion animals in urban informal settlements from Salvador, Brazil

Toxoplasma gondii is a globally neglected zoonotic parasite, particularly prevalent in socioeconomically vulnerable areas. Various animal species serve as reservoirs for T. gondii across different regions, including domestic cats, livestock, and a variety of wild and synanthropic animals. In urban areas, especially informal settlements, the close coexistence of humans, domestic animals, and wildlife may influence local transmission dynamics. This study evaluated the seroprevalence and associated risk factors for T. gondii infection in domestic and synanthropic animals from two low-income communities in Salvador, Brazil. A cross-sectional study was conducted in the neighborhoods of Marechal Rondon and Pau da Lima from October 2021 to February 2023. Blood samples were collected from domestic animals (288 dogs, 112 cats, 27 chickens, and six horses) and synanthropic species (54 brown rats and 75 big-eared opossums). Serological tests were performed using an indirect immunofluorescence antibody test. Questionnaires were used to collect environmental, demographic, and socioeconomic data from households where sampling took place. Generalized linear mixed models were applied to identify predictors of exposure. Seroprevalence was highest in chickens (66.7%), followed by dogs (37.2%), rats (24.1%), cats (22.3%), opossums (20%), and horses (16.7%). No significant factors were found to be associated with T. gondii seroprevalence in chickens, horses, rats, or opossums. Nevertheless, in dogs and cats, homemade diets increased the odds of infection by nearly six times compared to commercial feeding. Dogs from Pau da Lima were twice as likely to be infected as those from Marechal Rondon. These findings underscore the importance of promoting safe pet management, improving sanitation, and monitoring sentinel species to mitigate zoonotic risks in urban informal settlements. Author summaryToxoplasma gondii is a parasite that infects humans and animals worldwide, significantly impacting impoverished areas. In this study, we investigated the prevalence and factors associated with T. gondii infection in domestic and urban wildlife from two low-income communities in Salvador (BA, Brazil). We collected blood samples from dogs, cats, chickens, horses, rats, and opossums to test for antibodies against the parasite and analyzed environmental and lifestyle factors that might influence infection risk. Chickens showed the highest infection rates (67%), followed by dogs (37%), rats (24%), cats (22%), opossums (20%), and horses (17%). We found that homemade diets significantly increased the likelihood of infection in dogs and cats compared to commercial pet food. Additionally, dogs from one neighborhood were twice as likely to be infected as those from the other, likely due to environmental conditions. These findings highlight how diet, environment, and urban living conditions affect the spread of T. gondii. By improving sanitation, promoting responsible pet care, and monitoring animals that share human environments, we can reduce the risk of this parasite in vulnerable communities.

ecology↗

bioRxiv2023

Effect of Socio-environmental Factors on Rat Proliferation and Leptospira Transmission in Suburban Areas of Dungun, Terengganu, Malaysia

BackgroundRats play a significant role as important reservoirs in the transmission of neglected zoonotic diseases, such as leptospirosis, particularly in poor urban and suburban communities of Low and Middle-Income Countries. Their proliferation is influenced by poor socio-environmental conditions like poor housing conditions, improper refuse disposal, and open sewer which generally furnish rats with food, water and harborage sources. Several interventions have been targeted against rats, given their public health menace but with no significant success, probably due to insufficient knowledge about context-specific factors influencing their proliferation in poor environments. Methodology/Principal FindingsWe evaluated the effect of different socio-environmental conditions on rat proliferation and the possible outcome on the transmission of Leptospira in suburban environments. We performed ten trapping sessions between April 2021 and January 2022, and captured 89 small mammals from 1385 trapping efforts (specifically, Rattus norvegicus (n = 39), Rattus rattus (n = 27), Rattus exulans (n = 10), Suncus murinus (n = 11), and Tupaia glis (n = 2)), with a 15.7% (n = 14/89) of the captured animals testing positive for Leptospira bacteria using PCR detection. We used a generalized linear model to evaluate the effect of different socio-environmental variables on household rat infestation and reported residences without paved floors, the presence of animals/pets, residence type and residences with vacant lots as variables positively associated with rat proliferation in the study sites. ConclusionRats are widely and differentially distributed in the poor communities of Dungun. Besides R. norvegicus and R. rattus, S. murinus and T. glis could also maintain and encourage pathogenic Leptospira transmission in the study areas. To adequately control rats proliferation and subsequent human zoonoses transmission, it will be critical to advocate and promote appropriate infrastructure and urban services, together with good hygiene practices to reduce rats access to water, food and harborage. Author SummaryRats are important reservoirs in the transmission of urban and suburban leptospirosis, and their proliferation is generally supported by poor socio-environmental conditions. Despite the strong association between poor socio-environmental conditions, rat proliferation and leptospirosis transmission, few studies have characterized their relationships in many poor suburban environments. Therefore, we evaluated the effect of different socio-environmental conditions on rat proliferation and possible effect on leptospirosis transmission in suburban communities of Dungun, Malaysia. We performed rat trapping and captured 89 small mammals from three orders, with a 15.7% (n = 14/89) of the captured animals testing positive for Leptospira bacteria using PCR detection. Using a generalized linear model, we reported residences without paved floors, the presence of animals/pets, residence type and residences with vacant lots as variables that are positively associated with rat proliferation in the study sites. Our findings show that rats are widely distributed in the study sites, and that in addition to R. norvegicus and R. rattus, S. murinus and T. glis could also maintain and transmit pathogenic Leptospira. Given the variables associated with rats proliferation, it is crucial to promote appropriate infrastructure and good hygiene practices to reduce rats access to water, food and harborage and subsequent rodent-borne diseases.

ecology↗