Toxoplasma gondii infection in slaughtered domestic ruminants in Northwest Ethiopia: seropositivity, bioassay and virulence assessment

Abstract This study investigated the seropositivity, isolation and virulence of Toxoplasma gondii in slaughtered domestic ruminants in Gondar city, Northwest Ethiopia. Three hundred thirty-five blood samples (135 sheep, 50 goats and 150 cattle) were collected from slaughterhouses. Antibodies against T. gondii were assayed using a commercial Toxo-Latex agglutination test. Tissue digestion was also conducted on 39 heart muscles of seropositive animals using the pepsin enzyme. The isolation of viable T. gondii from seropositive ruminants was also performed in white albino mice. The overall seroprevalence of T. gondii infection was found to be 55.8%. The species-wise prevalence of T. gondii seropositivity in cattle, goats and sheep was 59.3%, 58%, and 51.1%, respectively. From observed risk factors, sex (p < 0.033) and age of the sheep (p < 0.006) showed a significant association with T. gondii seropositivity. Similarly, in cattle, age (p < 0.005) and breed (p < 0.012) showed a statistically significant association with seropositivity of anti-T. gondii antibodies. In bioassayed mice, the overall viable T. gondii isolates were 38.5% and most of these isolates (87.18%) were avirulent. In conclusion, the high prevalence of T. gondii antibody and a high proportion of viable T. gondii observed in this study indicated the prevalent nature of the parasite and its zoonotic importance in the study areas where slaughtered domestic ruminants serve as an important human protein source. Education of the public about routes of T. gondii transmission and control methods is imperative to prevent T. gondii transmission.