Seroprevalence and associated risk factors of Toxoplasma gondii in sheep and goats of mid-western Nepal with potential risk of human infections

IntroductionToxoplasma gondii is a protozoan that causes zoonotic disease in warm-blooded animals including humans worldwide. We aimed to evaluate the seroprevalence of T. gondii infection and associated risk factors in sheep and goats and analyze risk to farm attendants across three different eco-zones in mid-western Nepal. MethodsWe conducted a cross-sectional study of 368 sheep and goats in three districts representing distinct eco-zones and evaluated the seroprevalence by detecting T. gondii antibodies withan indirect enzyme-linked immunosorbent assay. Chi-square test was used to assess potential risk factors while spearmans rank correlation was used for risk assessment in farm attandants. ResultsThe herd-level and individual animal level seroprevalence of T. gondii infection was 92.8% (n = 64/69) and 61.7% (n = 227/368), respectively. Sheep had higher seroprevalence (81.4%, n = 136/167) than goats (45.3%, n = 91/201). Altitudinal gradient had a weak but positive correlation to the herd seroprevalence (r = 0.38). The high seroprevalence suggests that T. gondii is widespread in the study area and sheep and goats could serve as significant sources of transmission to humans. ConclusionAltitude, age of animal, type of host animal, herd size, rearing system, types of animals reared in a herd, presence of domestic cats and access of cats to water sources were detected as potential risk factors for T. gondii infection in sheep and goats. There is a need for additional epidemiological studies and interventions for appropriate prevention and control strategies for T. gondii infections in sheep, goats, and humans. Author summaryToxoplasmosis, caused by Toxoplasma gondii, is a widespread zoonotic disease that affects a wide range of warm-blooded animals, including humans. We evaluated the seroprevalence of T. gondii infection and its associated risk factors in sheep and goats across three eco-zones in mid-western Nepal. A total of 368 animals from three districts were included in this cross-sectional study. We found a high herd-level seroprevalence of 92.8%, with an overall individual animal seroprevalence of 61.7%. Sheep had a significantly higher seroprevalence (81.4%) compared to goats (45.3%). We also identified several risk factors associated with T. gondii infection, including altitude, animal age, host type, herd size, rearing system, and the presence of domestic cats. In addition, we assessed the behaviors of farm attendants, revealing a moderate correlation with the seroprevalence of T. gondii at the herd level. The high seroprevalence in sheep and goats suggests that these animals may play a key role in the transmission of T. gondii to humans, particularly in rural areas with close livestock-human interactions. The study highlights the need for additional epidemiological research and the development of targeted prevention and control strategies for T. gondii in livestock populations to reduce the risk of zoonotic transmission.