Analysis of Risk Factors Associated with Seroprevalence of Neospora caninum in Dairy Animals from Khartoum State, Sudan

Abstract

A cross-sectional study was conducted between October 2012 and April 2014 to determine the sero-prevalence and the main risk factors associated with the N. caninum infection in dairy cattle and co-herded camels, sheep and goats in dairy farms from the Khartoum State. A total of 906 serum samples from 645 dairy cows, 61 camels, 100 sheep and 100 goats were examined for specific N. caninum IgG antibodies using Competitive Enzyme Linked Immunosorbent Assay (cELISA) Diagnostic kits (VMRD). The overall seroprevalence of N. caninum at herd and individual levels were 32.2% (56/174) and 8.8% (80/906) respectively. The highest percent inhibition (pi) recorded was 93% with mean of 38.7�12.3 and 39.3�13.9 at herd and individual level respectively. Possible association of the N. caninum infection with the investigated risk factors was analyzed by univariate analysis and variables significant at p?0.25 were included in multivariate logistic regression models. The results showed that, There were no significant (p>0.05) differences in the seroprevalence of N. caninum among the regions and the different animal species. The univariate analysis included production system, source of concentrate, keeping dogs, other diseases (Toxoplasmosis) as risk factors associated with cELISA positive status of N. caninum infection. Region, herd size, herd type, source of fodder, brucellosis and stray dogs were not significant risk factors (p>0.05). The multivariate analysis indicated only production system (Intensive, p=0.019) and source of concentrate (Readymade, p=0.007) as the statistically significant (p<0.05) risk factors of being Neospora cELISA positive. The study also reported occurrence of abortion (72.4%), repeat breeding (76.3%), and stillbirth (18.4%) during interview with the owners of the investigated dairy herds. Interestingly, 18.2% of the aborted dams have repeated abortions. In conclusion, the authors believe that, the results of this study may provide a comprehensive data explaining the association of the main possible risk factors with N. caninum seropositivity in dairy animals. Research on abortifacients agents such as Neospora, Brucella, Toxoplasma and Listeria collectively is recommended to evaluate their individual role in the severe economical losses in dairy farm industry and for control strategy.