Seroprevalence, distribution and risk factor for peste des petits ruminants (PPR) in Algeria

Peste des petit ruminants (PPR) is a highly contagious and infectious viral disease of small ruminants with severe socio-economic implications. The disease was first reported in the Southern part of Algeria in 2011 and by February 2012 it has reached the central part of the country. Estimating national prevalence, distribution and identification of risk factors remains a key component in understanding the epidemiology and control of the disease. The present study was carried out between January and June 2014, to include a detailed description of flock and within-flock seroprevalence and risk association between PPR seropositivity and various flock management factors in Algeria. A total of 150 flocks randomly sampled across the country were investigated and 4552 serum samples were collected from 3336 sheep and 1216 goats, respectively. C-ELISA was used to detect the presence of antibodies in small ruminant animals as an indicator of PPRV exposure. The results showed an overall true flock seroprevalence of 30.45% [95% CI 23.76-37.14] with a mean of the true within-flock prevalence as 29.87% ± 2.11. The mean of the true within-flock prevalence in mixed flocks (12.93% ± 1.85) was however found to be significantly higher than sheep flocks (5.74% ± 1.06). Also the mean of the true within-flock prevalence was found to be significantly higher in adult (35.36% ± 3.13) compared to young animals (21.83% ± 2.47) and in females (33.11% ± 2.87) compared to males (22.14% ± 2.31). The univariate analysis revealed that PPR overall flock seroprevalence was significantly higher (P < 0.20) in large flock (50.61%) than in small flock (33.33%), in mixed flock (56.7%) than in sheep flock (35.35%) and in the flocks that had contact with other flocks (46.5%) compared to those who had not (30.6%). However the differences among studied regions and grazing system were not statistically significant. For the risk factor analysis, univariate analysis of variables followed by a multiple logistic regression identified mixed flocks [OR = 2.64, 95% CI 1.30-5.38; P = 0.007] and contact with other flocks [OR = 2.27, 95% CI 0.99-5.21; P = 0.053] as risk factors in the spread of the disease. In conclusion, this study revealed a high seroprevalence of PPR in Algerian small ruminants, therefore the establishment of early warning systems and comprehensive implementation of control measures are advocated to improve animal welfare and reduce economic losses.