Bioassay of Toxoplasma Gondii from Apparently Healthy Pigs Slaughtered in Addis Ababa Abattoir, Ethiopia

Toxoplasmosis is an infectious disease caused by the protozoan parasite Toxoplasma gondii that infects a wide range of animals, including man and birds. The objective of the study was to isolate T. gondii in pigs slaughtered at the Addis Ababa abattoir. A total of 290 sera were examined for T. gondii antibodies (IgG) using the Direct Agglutination Test (DAT) of which 111 pigs (38.28%; 95% confidence interval [CI]: 32.65%-44.14%) were seropositive. Hearts of fifty seropositive pigs and two pooled pig heart samples (portion of 4 pig hearts per pool) were used for the study. For the isolation of T. gondii, 50 g heart tissue was ground, digested with acid-pepsin and inoculated intraperitoneally into mice (5 mice/sample). Viable T. gondii was isolated from hearts of 24 of 50 (48%; 95% CI: 33.7%-62.6%) seropositive pigs and from the two pooled seronegative pig hearts. All isolates were asymptomatic except one isolate from Bishoftu which was lethal for mice on day 28 post-inoculation. There was a perfect agreement (k=0.85) between DAT and microscopic cyst detection in mice. The study suggests that pork containing viable T. gondii is released onto markets for consumers. Therefore, enforcing hygienic measures, public education, provision of rendering facilities and further studies deserve consideration. This is the first report of isolation of viable T. gondii from pigs in Ethiopia.