Outbreak investigation and molecular characterization of African horse sickness virus circulating in selected areas of Ethiopia

• Published in: Acta tropica 2013-08, Vol.127 (2), p.91-96
• Main Authors: Ayelet, Gelagay, Derso, Samuel, Jenberie, Shiferaw, Tigre, Worku, Aklilu, Nigatu, Gelaye, Esayas, Asmare, Kassahun
• Format: Article
• Language: English
• Subjects: African horse sickness; African Horse Sickness - epidemiology; African Horse Sickness - virology; African horse sickness virus; African Horse Sickness Virus - genetics; Animals; Data Collection; Disease Outbreaks; Equine; Ethiopia; Ethiopia - epidemiology; Health Knowledge, Attitudes, Practice; Horses; Humans; Molecular Epidemiology; Retrospective Studies; Risk factors; Surveys and Questionnaires; Virus serotype
• ISSN: 0001-706X; 1873-6254
• DOI: 10.1016/j.actatropica.2013.03.018

The study was conducted on African horse sickness disease with the aim of identifying type of serotype found in Ethiopia and determine the associated risk factors for the occurrence of the disease in Ethiopia. The finding revealed that serotype 9 is the only type identified and the disease occurrence is influenced by season, breed of animals and agro-ecology of the country. •The strain 9 was identified from all outbreak samples.•The highest rate of AHS outbreaks were reported during and following main rainy season.•Horse is the mainly affected species equids.•Illubabor, West Shoa, Arsi and Jima are the most highly affected areas in the country. The study was conducted from June 2011 to May 2012 in central, northern and western parts of Ethiopia to investigate and identify circulating serotypes of African horse sickness virus (AHSV). The indigenous knowledge of equine owners about AHS in the study areas was assessed and also the retrospective data of AHS outbreaks for 2011 were analyzed. Whole blood samples were collected for virus isolation and serotyping from diseased horses and mules showing typical signs of the AHS. Virus isolation on Vero cell and detection of AHSV genomes using conventional RT-PCR were conducted. Further molecular characterization and serotyping were done on positive isolates. The questionnaire survey revealed that equine owners do recognize AHS clinically and have a local name that varies in different regions. From the 72 equine owners interviewed about their knowhow of AHS, 48 (66.7%) of respondents were not aware of AHS disease mode of transmission. The retrospective disease report data showed that a total of 208 outbreaks were reported and 3036 cases and 1167 deaths were recorded in 2011. AHS outbreaks were more frequently observed from September to December and the highest number of outbreaks was recorded in October. During the study period totally six outbreaks were investigated and a total of 62 horses and 10 mules were found sick and all the four forms of AHS were observed. Cardiac form accounted for 52.8%, followed by African horse sickness fever form 31.9%, pulmonary form 8.4% and mixed form 6.9%. AHSV-9 was the only serotype circulating in the outbreak areas.