Browsing by Author "gebrezgabher, Weldegebrial"

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    Serological and participatory epidemiological study of Camelpox and field evaluation of vaccine in gabi rasu zone, Afar region, ethiopia
    (Addis Ababauniversity, 2015-06) gebrezgabher, Weldegebrial; Ayelet, Gelagay (PhD)
    Camelpox virus (CMLV) causes a smallpox-like illness in a unique host, the camel. Although the disease is enzootic in almost all regions where camel husbandry is practiced, and is responsible for severe economic losses, its epidemiology has not extensively investigated. Thus, sero- and participatory- epidemiological investigation of the disease was carried out in Gabi Rasu zone using cross sectional study design to determine its seroprevalence and associated risk factors as well as using seasonal calendar to identify its seasonal occurrences. In addition camelpox vaccine, the only available vaccine for the species of animal in Ethiopia, was evaluated under field condition by seroconversion using the before and after with control experimental study design. The study was conducted in two selected districts of Gabi Rasu zone, from November 2014 to May 2015. Out of 384 camel sera samples tested by virus neutralization test, 74 were seropositive for camelpox, giving an overall seroprevalence of 19.3% (95% CI= 15.3-23.2%) in the study area. A seroprevalence of 21.6 (95% CI= 16.0-27.2) and 16.7 (95% CI=11.2-22.1) were recorded in Amibara and Awash Fentale districts, respectively. At least one seropositive camel was detected from 25 herds among 30 examined giving 83.3% (95% CI = 70.0-96.6) herd level prevalence. Univariable and multivariable logistic regression analysis of the assumed risk factors showed that age of the camel was the only risk factor associated with the occurrence of serpositivity to camelpox. The results indicated that camelpox seroprevalence was significantly higher in adult (24.4%, 95% CI= 18.4-30.4) than young age group (13.9%, 95% CI= 8.9-18.8) with a 2 fold greater odds of occurrence. The small-scale vaccine evaluation trial indicated that, vaccination of camels with the live attenuated camelpox vaccine resulted in a significantly higher seroconvesrion rate compared to unvaccinated camels. However, among 58 vaccinated camels with pre-vaccination seronegative results, 32 found seropositive at postvaccination serum analysis using VNT, indicating low (55.2%) seroconversion rate. Various explanations have suggested for the failure of post vaccination seroconversion on 44.8% vaccinated camels. Interview of pastoralists has revealed that camelpox is one x of the most common camel diseases in the area. The disease was reported commonly to occur during the minor (Sugum) and major (Kerma) rainy seasons by informant groups. In conclusion camelpox seems to be endemic in Gabi Rasu zone with seasonal occurrence during rainy season. Therefore, considering the economical significance of the disease, vaccination of young camels along side training of pastoralists for improved management strategies could have a significant importance in diminishing the virus from circulation. However, further extensive studies that lead to conclusive results on the efficacy of the vaccine under evaluation are recommended. Key words: Afar, Camelpox, Participatory Epidemiology, Risk Factors, Seroprevalence, VNT