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

Abstract

This study aimed to determine the seroprevalence levels of T. 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, respectively, were collected from 22 farming establishments. An IDEXX Toxotest Ab®, a commercial ELISA kit, was used to test 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 0.29% (1/345) of the goat sera were positive, and only one of the 19 goat flocks had at least one positive animal giving a herd-level prevalence of 5.26%. 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 seropositive cases. Eight risk factors were evaluated, including the total number of goats, total number of sheep, farm size, average rainfall, level of Feliformia, history of abortions and the presence of domesticated cats and strays. Seropositivity to T. gondii was positively associated with the total number of sheep at the farming establishment, history of abortions and farm size (p < 0.05), but not goats. The study concluded that sheep were probably more susceptible to toxoplasmosis than goats and that the T. gondii seroprevalence level in the Khomas region was very low compared to other countries.