Knowledge, attitudes and practices analysis, prevalence and molecular detection of Neospora caninum and Toxoplasma gondii in livestock in the Khomas region of Namibia

Abstract

This study chiefly focussed on the Khomas region of Namibia, and the research areas were: (1) the knowledge, attitudes and practices regarding neosporosis and toxoplasmosis among livestock farmers in the Khomas region and animal health practitioners in the whole country; (2) the seroprevalence and associated risk factors of Neospora caninum in cattle; (3) the seroprevalence and associated risk factors of Toxoplasma gondii in sheep and goats; (4) molecular investigation of N. caninum DNA in cattle and, (5) the molecular detection of T. gondii in sheep and goats in abattoir samples. Only 15.9% (10/63) of the livestock farmers had heard about neosporosis or toxoplasmosis or knew how animals get infected (p<0.0001). Five per cent (3/63) of the farmers knew the risks associated with keeping dogs and cats concerning neosporosis and toxoplasmosis, respectively (p<0.0001). None of the animal health practitioners (n=51) routinely requested N. caninum or T. gondii laboratory tests in cases of cattle, sheep or goat abortions. Although all animal health practitioners indicated they routinely interacted with livestock farmers, none regularly discussed neosporosis or toxoplasmosis. Five point seven per cent (42/736) of the bovine sera were seropositive to N. caninum. Eight of the 32 establishments had at least one positive animal, giving a herd-level seroprevalence of 25%. There was no significant association between N. caninum seropositivity in cattle and the presence of dogs, jackals, history of abortions, farm size, and the number of cattle or average annual rainfall. The establishments with moderate to high numbers of Feliformia were 9.8 times more likely to be seropositive to N. caninum than those with none to low levels of the former (p=0.0245). Overall, 3.68% (11/299) of the sheep sera were seropositive to T. gondii, 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 seropositive to T. gondii, and 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 flocklevel 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. 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 exposed to T. gondii infection than goats and that the T. gondii seroprevalence level in the Khomas region was very low compared to other countries. One hundred and ninety-nine bovine abattoir samples were collected from different animals, comprising 110 brain samples and 75 heart muscle samples. In addition, there were 14 whole blood samples from N. caninum seropositive cattle. The collected samples were tested using a conventional PCR targeting the pNc5 gene. All the samples tested were negative. The authors concluded that the negative results could be due to the low prevalence of N. caninum infection caused by adverse weather conditions and that a future study targeting aborted fetuses over a more extended period could yield positive results. The T. gondii molecular study analysed 174 brain and heart tissue samples from sheep and goats for the presence of T. gondii DNA using nested PCR targeting the B1 gene. The tissue samples were obtained from animals at abattoirs designated for human consumption. The study found that 16.7% of the samples tested positive for T. gondii DNA, with a higher prevalence in sheep (17.4%) than in goats (7.7%). Eight of the 29 positive samples were successfully sequenced using the Sanger method. All isolates identified were closely related to T. gondii type III genotype, exhibiting alignment scores ranging from 96.44% to 100%. This study emphasizes the public health hazards of consuming undercooked sheep and goat meat and highlights the pressing need to introduce control measures to mitigate human exposure.