Veterinary Epidemiology

Permanent URI for this collection

http://etd.aau.edu.et/handle/123456789/112

Browse

Browsing Veterinary Epidemiology by Subject "African horse sickness virus"

Now showing 1 - 1 of 1
  • No Thumbnail Available
    Item
    Outbreak Investigation and Molecular Epidemiology of African Horse Sickness Virus Circulating in Central, Eastern and Southern Parts of Ethiopia
    (Addis Ababa University, 2011-06) Nigatu Aklilu; Yilkal Asfaw; Esayas Gelaye; Gelagay Ayelet
    This study was conducted from September 2009 to December 20 lOin central, eastem and western patts of Ethiopia to investigate and identify circulating serotypes of African horse sickness virus (AHSV). A total of ten outbreaks were investigated in the study period. Samples collected for virus isolation and identification were whole blood in ethylene diamine tetra-acetic acid (EDTA) from diseased horses and mules, and tissues from freshly dead horses. AHSV isolation on Vero ce ll line and detection of AHSV genomes using conventional RT-PCR were archived in the National Veterinary Institute (NY!) molecular laboratory, Debre Zeit, Ethiopia. Samples were sent for further viral isolation, identification, sequencing and phylogenetic analyses in the Non-vesicular Laboratories of Institute of Animal Health (!AH), Pirbright, United Kingdom (UK). A total of 336 sera were collected from apparently healthy equids that were either unvaccinated or have vaccination history of before three years in Cheat and Tikur Inchini districts and subjected to a serological test using a commercialized blocking enzyme linked immunosorbent assay (ELISA) kit. A questionnaire survey was administered to 178 equine owners and retrospective data of outbreaks for three years obtained from Animal and Plant Health Regulatory Directorate (APHRD) in the Ministry of Agriculture (MoA) were analyzed to see the national picture and seasonality of outbreaks. A total of 48 horses died of African horse sickness (AHS) during the outbreaks. Ada'a district was the major outbreak site where the outbreak involved a number of towns and villages. A total of 81 horses and 3 mules were affected and 46 (54.8%) of them demonstrated cardiac form of the disease while the rest 30 (35.7%), 6 (7. 1%), 2 (2.4%) were affected by horse sickness, pulmonary and mixed forms of AHS, respectively. Multiple serotypes of AHSVs were identified from the submitted samples by quantitative real-time RT-PCR and sequencing. AHSV-4, AHSV-6, AHSV-8 and AHSV-9 serotypes were identified. Identification of A HSV -4, AHSV -6 and AJ-ISV -8 are reported for the first time in Ethiopia. AJ-ISV -9 was the dominant serotype circulating in the outbreak areas. Serotypes identified from the outbreaks were phylogenetically compared with the reference stains in IAH, Pirbright, UK. A total of 147 (43.8%) of the sampled equids were found seropositive for antibodies against AHSV. The respective seropositivity of equids in Cheat and Tikur Lnchini districts were 49.4% and 37.8% (p= 0.032). Statistically significant difference was not observed between risk factors of species, age and sex (p > 0.05). From the total 178 respondents 71 (40%) of them indicated that their indigenous knowledge on the disease, its transmission and control measures is unsatisfactory while the rest (60%) were aware of the disease. Local names used for AJ-IS were 'Derbetu ' or 'Dibe Ferda ' in Tikur Inchini and 'Horyo' in Cheta. Locally known equi ne flies were 'Bombisa ' in Tikur lnchini and 'Gemo' and 'Yubo' in Cheta. A total of 482 outbreaks were recorded retrospectively from Oromia (80.1 %), Amhara (10.6%), Southern Nati on Nationalities and People 's Regional State (SNNPRS) (7.7%) and the rest from Tigray, Dire Dawa and Afar regional states. AHS outbreaks were more frequently observed fi·OI11 September to December and the highest number of outbreaks was reported in 2008. Generally, the identification of multiple serotypes in the Crrnent study indicated increased risk and devastating outbreaks of AHS is a possibility. The production of polyvalent vaccine which confers protection against the identified serotypes and prophylactic vaccination of horses and mules are recommended. Key words: African horse sickness virus, equine, Ethiopia, outbreak, RT-PCR, serotype.