The article reviews the outbreaks and distribution of African swine fever (ASF) in South Africa since the first probable outbreak that occurred in the Koedoesrand Ward in 1926. Retrospective data on the ASF outbreaks in South Africa were obtained from the World Organisation for Animal Health (OIE) disease database and the South African veterinary services annual reports in addition to published articles and online sources. South Africa has experienced many outbreaks that can be divided into 2 time periods: the period before the development of the OIE diseases database (1993) and the period after. More than 141 outbreaks of ASF were reported during the first period. Since the development of OIE disease database, 72 outbreaks directly involving 2968 cases, 2187 dead and 2358 killed pigs mainly in smallholder pig farms were reported. The median number of cases for a given ASF outbreak is 17, but in 50% of outbreaks no pigs were killed for prevention. The most important ASF outbreak was reported in April 2014 in the Greater Zeerust district (North West province) involving 326 cases and 1462 killed pigs. However, the outbreak with highest mortality involving 250 pigs was reported in 2016 (Free State province). According to phylogenetic analysis, nine p72 genotypes (I, III, IV, VII, VIII, XIX, XX, XXI and XXII) have been identified in South Africa. Season-wise, more outbreaks were recorded during summer. It was also observed that the OIE disease database could contain errors that would have been introduced through compiled forms at country level. Spatiotemporal studies on ASF outbreaks in South Africa are therefore required in order to assess statistically and quantitatively the clustering of outbreaks over space and time.

This study was carried out for investigation of an outbreak in Karachi. A disease outbreak in poultry was reported during April, 2000 in Karachi. The main symptoms included respiratory distress, sneezing and gasping. Autopsy of dead birds showed tracheitis, air-sacculitis and involvement of lungs. The morbid material was collected for processing in the laboratory. During the investigation for isolation of pathogenic bacteria or virus, Ornithobacterium rhinotracheale was isolated on 5% sheep blood agar plates in an atmosphere containing 5-10% CO2 at 37 degree C and identified through biochemical and fermentation tests. A Lasota like virus was also isolated from the same material which showed HA activity but was found negative to Avian Influenza virus against known Avian Influenza serum. The isolated virus was sent to Central Veterinary Laboratory, Weybridge, U.K. which confirmed it to be Lasota virus having comparatively high Intracerebral Pathogenicity Index (ICPI) as 0.90. Attempts for the transmission of the disease in susceptible healthy broiler chicks was successful through aerosol route using combination of inoculum of the isolated bacteria and virus. On post-mortem of infected birds air- sacculitis, tracheitis and unilateral pneumonia were noticed. Again ORT and NDV were isolated from the material harvested from these chicks. According to the observations of these experiments, it was concluded that the isolated ORT had a triggering effect on Lasota virus or vice versa. The environmental temperature and other stress factors might have aggravated the disease problem.