Investigation of African swine fever outbreaks in pigs outside the controlled areas of South Africa, 2012-2017.

Leana Janse Van Rensburg,Mary-Louise Penrith,Juanita Van Heerden,Thapelo Rametse,Eric M C Etter,Livio E Heath

doi:10.4102/jsava.v91i0.1997

Abstract

South Africa historically experienced sporadic African swine fever (ASF) outbreaks in domestic pigs in the northern parts of the country. This was subsequently indicated to be because of spillover from the sylvatic cycle of ASF between warthog and tampans (soft ticks) in the area. South Africa declared this area an ASF-controlled area in 1935, and the area is still controlled in terms of the Animal Diseases Act, 1984 (Act 35 of 1984). Two main epidemics of ASF in domestic pigs were identified outside of the South African ASF-controlled area. The first occurred in 2012 with outbreaks in Gauteng and Mpumalanga provinces, and the second occurred in 2016–2017 with outbreaks in the North West, Free State and Northern Cape provinces. These were the first ASF epidemics in South Africa associated with transmission of the disease via a domestic cycle. This study found that the spread of ASF in these epidemics was mainly via auctions, swill feeding and scavenging. These three aspects need to be addressed in terms of awareness and education on the disease including implementation of biosecurity measures in order to prevent future ASF outbreaks in South Africa. Specific biosecurity measures should be implemented in the semi-commercial sector to prevent ASF-infected pigs and pig products from being moved to naïve pigs and therefore spreading the disease.

Highlights

African swine fever (ASF) in domestic pigs is a devastating disease and one of the main limitations for pig production in sub-Saharan Africa (Fasina et al 2012; Penrith 2009)
The minutes of the meetings held by the ASF Veterinary Operational Committee, as well as communication between the South African Pork Producers’ Organisation (SAPPO) and DAFF relating to the ASF outbreaks, were utilised for supplementary information
This was the first widespread outbreak of ASF outside of the ASF-controlled area, as well as the first series of outbreaks of ASF that resulted from a domestic cycle, even though the original source of the outbreaks according to back-tracing was likely spillover from the sylvatic cycle within the ASF endemic area of South Africa

Summary

Introduction

African swine fever (ASF) in domestic pigs is a devastating disease and one of the main limitations for pig production in sub-Saharan Africa (Fasina et al 2012; Penrith 2009) This haemorrhagic disease usually has a very high mortality rate, and currently no vaccine is available as a means of prevention, nor is there any means of treatment (Bastos, Fasina & King 2014; Costard et al 2009; Penrith & Vosloo 2009). This, combined with the ASF virus (ASFV) stability and persistence in meat products that have not been processed sufficiently to inactivate the virus, has led to the dissemination of the disease along transport and trading routes (Bastos et al 2014). This potential for rapid spread of the disease makes it imperative that the disease be promptly diagnosed and control measures enforced to prevent the disastrous economic and social consequences of outbreaks (Chenais et al 2017; Etter et al 2011)

Objectives

Methods

Results

Discussion

Conclusion