Sero-prevalence and associated risk factors of peste des petits ruminants and contagious caprine pleuro-pneumonia in goats and sheep in the Southern Zone of Tanzania

摘要

A retrospective Sero-prevalence analysis was conducted in 2012 in order to find out whether contagious caprine pleuro-pneumonia (CCPP) and peste des petits ruminants (PPR) had already been introduced in Mtwara and Lindi regions of Southern Tanzania by 2007 and 2009. A total of 477 randomly selected sera from a bank of 3500 small ruminant samples that were collected as part of Rift Valley Fever surveillance of 2007 in Mtwara and Lindi regions were used in this study. Seroconversion was also evaluated in the 504 sera that were collected in 2009 as part of disease outbreak investigations in Tandahimba and Newala districts of Mtwara region. Seroconversions to CCPP and PPR were tested using competitive ELISA. In addition, information on different variables available in the existing surveillance forms gathered during sampling was used in the analysis of risk factors associated with seropositivity to the two diseases. The overall seroprevalence of CCPP for the sera of 2007 and 2009 in goats was 52.1% (n=447) and 35.5% (n=434) respectively; while in sheep the seroprevalence was 36.7% (n=30) and 22.9% (n=70) respectively. Seroconversion to PPR in goats and sheep was 28.7% (n=434) and 35.7% (n=70) respectively based on the sera of 2009. However, no antibodies were detected in the 2007 sera. Mixed infections were detected in 7.4% (n=434) of the goat and 12.9% (n=70) of sheep samples. Significant risk factors associated with seropositivity to CCPP in 2007 included introduction of new animals in flocks (OR=3.94; 95% CI 1.86-8.36; p<0.001) and raising animals in government farms (OR=4.92; 95% CI 1.57-15.76; p=0.02); whereas, seropositivity to CCPP in 2009 increased with introduction of new animals in flocks (OR=18.82; 95% CI 8.06-43.96; p<0.001), raising animals in government farms (OR=4.04; 95% CI 2.69-6.42; p<0.001) and raising animals in Newala district (OR=2.35; 95% CI 1.53-3.62; p<0.001). On the other hand, predictors for seropositivity to PPR in 2009 were introduction of new animals in flocks (OR=2.83; 95% CI 1.73-4.62; p<0.001) and communal grazing of animals (OR=7.60; 95% CI 1.77-32.58; p=0.01). Therefore, these results show that CCPP was already circulating in goats in the southern zone by 2007 and that PPR was probably introduced thereafter. Their presence in this emerging animal keeping area in Tanzania calls for improved surveillance and control systems