RISK ASSESSMENT AND MANAGEMENT FOR PESTE DES PETITES RUMINANTS (PPR) IN SUDAN

Abstract

Peste des Petits Ruminants (PPR) is a highly contagious viral disease of small ruminants with a confirmed circulation in other species such as camels. PPR is one of the most important economical diseases in Sudan. In the present research some of the potential risk factors associated with PPR were investigated using a cross- sectional and case- control studies, and then a preliminary qualitative assessment for PPR risk in exported sheep was carried out to determine a risk- based control measures. The thesis is composed of three studies, the first one is a seroprevalence and risk factors of Peste des Petits Ruminants (PPR) were studied in unvaccinated sheep and goats in Sudan. A total of 480 sera samples were collected from the sheep (n=261) and goats (n=219) of Sennar, Gedarif, River Nile, and North Kordofan states during May, June, and October 2012 and February 2013, respectively. The sera were tested for the presence of antibodies against PPR using competitive Enzyme Linked Immunosorbent Assay. The overall seroprevalence of PPR was recorded as 45.6% (n=219/480); whereas, 57.2% in Sennar, 46.2% in Gedarif, 34.9% in River Nile and 39.8% in North Kordofan. A total of 14 risk factors were investigated using structured questionnaire, of which 9 were found to be associated with PPR seroprevalence (p≤0.05). Among the localities, Abozabad located in North Kordofan had the highest prevalence (91.7%) of PPR followed by Barbar in River Nile. PPR seroprevalence was higher in pastoralists, animals housed in scarp fences, females, and Kwahla sheep. In addition, PPR was higher in the states that had high rainfall and wind-speed. The associated 9 factors were further analyzed multivariably by logistic regression, and finally 5 of them (states, localities, husbandry system, gender, and age) were found to be associated with PPR seroprevalence (p≤0.05). The second is a case- control study for PPR outbreaks to investigates some environmental and management risk factors in Sudan in the period from 2008 to 2012. One hundred and fourteen Localities from 14 states out of 15 were divided into cases (n= 47) and controls (n= 67) according to the PPR outbreak history; cases are localities with PPR outbreaks through the five years of the study while controls are the localities which haven’t reported any outbreak during the study period. Data about seven risk factors were collected and analysed using SPSS software, the factors are; ecological zone, annual rainfall, wildlife density, location at border with a foreign country, vaccination coverage against PPR, Sheep and goats population and State area. In the univariate analysis Odds Ratios (OR) were calculated using mantel Haenszel test and three factors were found to have a significant association with the occurrence of PPR outbreaks; being a locality in a state at the country borders (OR = 2.942, p-value= .019), or locality in Low rainfall ecological zone (OR = 2.134, P-value=.052) and the factor of having large size population of small ruminant (OR = 1.591, p- value=.251). These potential risk factors were entered into a multivariate analysis using logistic regression and only the factor of being at the border with a foreign country was found to be significantly associated with PPR occurrence (P- value = .027). The third study is a preliminary qualitative risk assessment for PPRV spread among sheep exports value chain using the OIE frame work for import risk analysis with some adjustments as to fit with an assessment for an endemic disease, together with value chain analysis designed by FAO for disease management. The overall estimated risk for PPR spread in sheep exports value chain was found to be Low. The PPR release risk in sheep value chain, XV which represent the probabilities of PPRV existence in sheep herds prior to send to livestock markets, within markets, in addition to the virus probabilities to spread in the internal quarantine, and was found to be Medium, which means that the risky event is likely to occur more than once in the next three years. The exposure risk which represent the probability of PPRV to spread among the sheep herds selected for exportation and it is depending on the contact with an infected sheep or fomites within the transporting trucks to the terminal quarantine or / and in the terminal quarantine or / and in the fomites of the transporting ship to the importing country. In this study the exposure risk was assessed to be very low (V Low), that means the risk of PPRV spread is rare (the risky event may occur in exceptional circumstances). Finally research conclusions were summarized in the end of the chapters and according to the findings of chapter four and the studied risk factors; control and prevention measures were recommended.