During 1995/1996 parts of South Africa experienced exceptionally
high rainfall. Large numbers of Culicoides midges were seen and an
outbreak of African horse sickness (AHS) followed. In the Onderstepoort
area, near Pretoria in Gauteng, a number of horses died of suspected
AHS. Virus isolation and typing was done from blood and/or organ samples
of 21 suspected cases as well as from 5 zebra which were kept in the
area. Virus was isolated from 14 of the 21 suspected cases but not from
the zebra. The neutralizing antibody response of the zebra to the nine African
horsesickness virus (AHSV) serotypes was determined. Results indicated the highest prevalence of
serotypes 2 and 4 followed by serotypes 1, 6 and 9. Reverse
transcription polymerase chain reaction (RT-PCR) was performed on total
RNA extracted from blood samples of the zebra. AHSV RNA was detected in
three of five zebra by agarose gel electrophoresis analysis of amplicons and in
four of five zebra after Southern blot hybridization using a 32P-labelled
probe. RT-PCR can be used together with serological techniques in
studies of AHS to further clarify the epizootiology of the disease.
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