Peste Des Petits Ruminants(PPR) introduction into Northern Zambia via live Goat consignments: A risk assessment study

Abstract

Peste des petits ruminants (PPR) was recently reported in Zambia’s neighbouring countries of Tanzania, Democratic Republic of Congo (DRC) and Angola. This situation presents a threat of illegal and legal trade-related incursions of the disease into Zambia. To determine the likelihood of this event, qualitative and quantitative risk assessments were performed using the OIE risk analysis framework, evaluating the risk of introducing PPRV into northern Zambia from Tanzania via live goat trade. The assessment was based on data collected during a four week mission to Tanzania and three districts in northern Zambia. Information was also obtained from published and grey literature, and online searches. Using a binary outcome Markov Chain model, the risk of PPRV introduction into northern Zambia was qualitatively evaluated as a function of the product of the probability of hazard (PPRV) release, exposure of susceptible hosts and the consequences of spread beyond the index case. These elements were assessed using the following parameters: prevalence of infection, volume of trade, competitive enzyme linked immunosorbent assay (C-ELISA) and quarantine screening missing an infected animal, capacity of the PPRV to survive in transit, and the virus potential for infection. The magnitude of the consequences was derived from the probability of transmission and spread and the impact of PPR introduction and establishment. Taking into account the combination of the above parameters, the probability of occurrence of PPR into northern Zambia was rated as “high”. The economic consequences of potential transmission and spread of PPR was also rated as “high.” Finally, the overall risk of introducing PPR into northern Zambia from Tanzania at the time of the assessment was rated “high.” At 95% level of confidence, the quantitative assessment revealed that the annual risk of introducing PPR from Tanzania into Zambia through importation of at least one infected live goat from an annual consignment of 4612 animals from Tanzania was evaluated to be approximately 1 or 100%. Therefore, the probability that PPRV will be introduced in Zambia through importation of live goats from Tanzania is high. It can therefore be concluded that import of goats and sheep be prohibited until efficient and adequate measures to reduce the risk have been put in place and verification procedures be effected to ensure safe implementation. The sensitivity analysis, revealed that the prevalence of PPR in goats in Tanzania was the major contributor to the ultimate risk. Therefore importing goats from the disease free areas could significantly reduce the risk. Since Zambia has not yet reported PPR disease, it is also possible that small ruminants in the study area are naïve to the disease and as such are prone to infection once exposed. This is shown in the sensitivity test where the spread of the disease will be high and causing huge financial loses. A few points for risk management options such as quarantine, vaccination and emergence preparedness are discussed.