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

Abstract Purpose This study investigated the seropositivity, isolation and virulence of Toxoplasma gondii in slaughtered domestic ruminants in Gondar city, Northwest Ethiopia. Methods 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, and isolation of viable T. gondii, from seropositive ruminants, was also performed in white albino mice. Results The overall occurrence of T. gondii infection was 55.8%. The occurrence of T. gondii antibodies in cattle, goats and sheep was 59.3%, 58%, and 51.1%, respectively. Toxoplasma gondii antibodies prevalence was significantly higher in females (χ2 = 4.55, p < 0.033) and adults of sheep (χ2 = 7.57, p < 0.006). Similarly, in cattle, old groups (χ2 = 7.81, p < 0.005) and cross-breeds (χ2 = 6.30, p < 0.012) have presented association with presence of T. gondii antibodies. However, in goats, no association was observed either with sex or age groups. In bioassayed mice, the overall viable T. gondii isolates were 38.5% and the parasites were isolated from samples of sheep (8/16), cattle (3/14) and goats (4/9), and most of these isolates (87.2%) were avirulent. Conclusion The high occurrence of T. gondii antibodies 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.