Seroprevalence and associated risk factors for Toxoplasma gondii infection of goats and sheep in the Khomas region of Namibia

This study aimed to determine the seroprevalence levels of Toxoplasma gondii in small ruminants (goats and sheep) and the associated risk factors in the Khomas region of Namibia. A total of 299 and 345 sheep and goat sera from 22 farming establishments were tested, respectively. An IDEXX Toxotest Ab((R)), a commercial ELISA kit, was used to screen for IgG antibodies to T. gondii. Overall, 3.68% (11/299) of the sheep sera were positive, and 61.54% (8/13) of the sheep flocks tested had at least one positive animal. Only one of the 345 goat sera from 19 flocks was positive, giving animal-level and herd-level prevalences of 0.29% and 5.26%, respectively. Sheep flocks had significantly greater animal-level and flock-level prevalences than goats (p < 0.05) and were 13.14 times more likely to be seropositive (OR = 13.14; CI 95%: 1.686-102.382) than goat flocks. A questionnaire was also administered to identify any putative risk factors associated with seropositivity. Eight risk factors were evaluated, including the total number of goats, total number of sheep, farm size, average rainfall, presence of wild Felidae (African lions, caracals, cheetahs and leopards), presence of domesticated and stray cats and history of abortions in the flocks. Seropositivity to T. gondii in sheep was positively associated with the total number at the farming establishment, history of abortions and farm size (p < 0.05), but not with goats. The study determined that sheep in the Khomas region were probably more exposed to T. gondii infection than goats. It also found T. gondii seroprevalences that were much lower than those in similar studies from other countries in the sub-region and elsewhere.