Below average rainfall across large swathes of South Africa appears to have been a driving factor behind fewer cases of deadly African horse sickness in the year ended August 31.
The nation’s annual report from the Department of Agriculture, Forestry and Fisheries showed it was the best year since 2012.
African horse sickness is caused by a deadly virus that is spread by the Culicoides imicola and C. bolitinos biting midges.
It is seasonally endemic in the northeastern part of South Africa, with seasonal epidemics spreading to the south and west of the country.
The department’s Animal Health Directorate, which produced the report covering the year from September 1, 2014, to August 31 this year, said favourable climatic conditions increased the breeding and spread of the midges. Periods of drought followed by heavy rain were particularly favourable for the insects.
The report noted that large parts of the country had received lower than average rainfall, particularly over large areas of KwaZulu-Natal, Limpopo, North-West, Northern Cape and Western Cape. Very few areas received above average rainfall.
There was a generally low occurence of African horse sickness in the 2015 season, the report said. The peak months were March, April and May.
There are nine serotypes of the virus known to be circulating in South Africa. Six out of the nine were detected by laboratory testing during the year – serotypes 1, 3, 6, 7, 8 and 9.
The report said there were 304 outbreaks in total, based on laboratory and other official reports.
Gauteng Province had the highest number of reported outbreaks, at 165. Northern Cape Province (5), Free State (5) and Western Cape Provinces (1) had the fewest.
The report can be read here.