Serum samples of 930 sheep were tested by ELISA to assess the prevalence of anti-Toxoplasma gondii antibodies and to identify risk factors associated with the presence of toxoplasmosis in two regions of Rio Grande do Norte (Northeast Brazil), with different climatic conditions. The overall estimated prevalence was 22.1%, with 26.3% and 17.8% positive sheep in Leste Potiguar and Central Potiguar regions, respectively. Among the positive sheep, 18.1% had low-avidity IgG antibodies, suggesting the occurrence of recent toxoplasmosis. The risk factors for toxoplasmosis in sheep were: presence of cats (odds ratio (OR) = 1.55; confidence interval (CI) 95% = 1.11–2.16), age of the animals, with adults presenting a greater chance of infection (OR = 2.44; CI 95% = 1.58–3.75), and the use of running water (OR = 1.61; CI 95% = 1.25–2.09), characterizing the existence of transmission by sporulated oocysts of T. gondii in the environment.

Toxoplasmosis is caused by Toxoplasma gondii, which is the main causative agent of abortion in small ruminants. Goats are among the animals that are most susceptible to this protozoon, and the disease that it causes leads to significant economic losses and has implications for public health, since presence of the parasite in products of goat origin is one of the main sources of human infection. Because of the significant economic impact, there is an urgent need to study the prevalence of T. gondii infection among goats in Sertão do Cabugi, which is the largest goat-producing region in Rio Grande do Norte. In the present study, the ELISA assay was used to test 244 serum samples from nine farms, located in four different municipalities in the Sertão do Cabugi region, which is an important goat-rearing region. The results showed that the prevalence of anti-T. gondii antibodies was 47.1% and that there was a significant association between positivity and the variables of age (≥ 34 months), location (Lajes, Angicos and Afonso Bezerra) and farm (all the farms). The avidity test was applied to all the 115 ELISA-positive samples to distinguish between acute and chronic infection. One hundred and three samples (89.6%) displayed high-avidity antibodies, thus indicating that most of the animals presented chronic infection, with a consequent great impact on the development of the goat production system and a risk to human health.Keywords: Toxoplasma gondii infection, goats, avidity ELISA, anti-T. gondii antibodies, risk factors. ResumoA toxoplasmose é causada pelo Toxoplasma gondii, principal agente causador de aborto em pequenos ruminantes. Os caprinos são uns dos animais mais suscetíveis a esse protozoário, levando a perdas econômicas significativas e implicações para a saúde pública, uma vez que a presença do parasito em produtos de origem caprina é uma das principais fontes de infecção humana. Devido ao impacto econômico significativo torna-se urgente estudar a prevalência da infecção, pelo T. gondii, entre caprinos do Sertão do Cabugi, a maior região produtora de caprinos no Rio Grande do Norte. O presente estudo utilizou o ELISA para testar 244 amostras de soro de 9 fazendas, situadas em 4 diferentes cidades na região do Sertão do Cabugi; uma importante região de criação de cabras. Os resultados mostraram uma prevalência de 47,1% para anticorpos anti-T. gondii e uma significativa associação entre a positividade e as variáveis idade (≥ 34 meses), localização (Lajes, Angicos e Afonso Bezerra e propriedade (todas as fazendas). O teste de avidez foi aplicado a todas as 115 amostras positivas pelo ELISA para discriminar entre infecção aguda e crônica. Cento e três amostras (89,6%) apresentaram anticorpos de alta avidez; indicando que a maioria dos animais estavam em infecção crônica, gerando um grande impacto sobre o desenvolvimento do sistema de produção em cabras e um risco para a saúde humana.Palavras-chave: Infecção por Toxoplasma gondii, caprinos, ELISA de avidez, anticorpos anti-T.gondii, fatores de risco.