A Quantitative Risk Assessment of Introducing Peste des Petits Ruminants (PPR) into Malawi Through Importation of Live Small Ruminants from Tanzania
The trade of small ruminants and their products requires reliable data on the risk of spreading livestock diseases such as peste des petits ruminants (PPR). Despite many transmission pathways for the PPR virus, there are increasing fears that the virus may be introduced into Malawi through the importation of live small ruminants such as sheep and goats. A quantitative risk assessment model was formulated to establish the scenarios that could lead to the introduction and sustenance of the PPR virus through the importation of live small ruminants from Tanzania. The @RISK software was used with Monte Carlo simulation at 10,000 iterations. The probability of introducing one PPR infected small ruminant through the importation of live small ruminants was estimated to be less than 0.006 at 95% confidence interval. A critical pathway analysis showed that the risk of introducing PPR virus into Malawi through this route would be largely affected by the probability of selecting an infected animal at the farm of origin in Tanzania. The variability/uncertainty associated with this probability was found to be 0.69. Assuming an expected annual importation of 250 to 1000 (most likely = 500) live small ruminants, the expected number of PPR infected live small ruminants would range from 0 to 14 (mean = 1.2) per year.