One Health Epidemiology, Associated Risk Factors and Molecular Characterization of Toxoplasma gondii at the Human–Small Ruminants–Cat Interface in Lahore, Pakistan

Toxoplasma gondii (T.gondii) is a food-borne and zoonotic parasite that causes human and animal diseases worldwide.In this study, the epidemiology, factors associated with seropositivity, and molecular characteristics of T. gondii at the human-small ruminants-cat interface have been explored in Lahore, Pakistan, using the One Health perspective.Blood samples were taken from sheep (n=1000), goats (n=1000), and humans (n=200) and tested for anti-T.gondii IgG antibody levels using an indirect enzyme-linked immunosorbent assay (iELISA).A structured questionnaire was used to evaluate the potential risk factors, and selected biochemical parameters were analyzed to evaluate the physiological effects of infection.The presence of the parasite was assessed using microscopy, followed by PCR, sequencing, and phylogenetic analysis of positive samples from 200 cat fecal specimens.The overall seroprevalence of T. gondii was 23.0%, 28.0%, and 27.0% in sheep, goats, and human participants, respectively.Sex, age, reproductive status, and grazing system were associated with seropositivity in small ruminants; cat access to feed was associated with seropositivity in goats, while cat ownership was associated with seropositivity in humans.Biochemical changes in the serum were noted in seropositive small ruminants and humans.Microscopic examination detected T. gondii-like oocysts in 7 (3.5%) of feline fecal samples, with six confirmed via PCR and further analyzed by partial SAG2 gene sequencing.Phylogenetic analysis suggested limited genetic variation among the analysed feline-derived isolates.The results indicate that T. gondii is a ubiquitous parasite in humans, animals, and cats and highlight the importance of the human-small ruminants-cat interface in disease transmission.The present study contributes to the implementation of integrated One Health surveillance and control strategies to minimize the impact of toxoplasmosis and safeguard public and animal health.