An outbreak of African swine fever in small-scale pigs, Gauteng, South Africa, July 2020

Objectives: Since 2012, outbreaks of African swine fever (ASF) in domestic pigs have increased outside of South Africa's ASF control zone. This study describes the epidemiological investigation and findings of an ASF outbreak in a small-scale pig unit in Gauteng Province and makes recommendations to prevent future outbreaks. Methods: PCR testing and molecular analysis were performed on pig tissue samples. Veterinary services conducted epidemiological investigations, forward and backward tracing, and surveillance. Farm management and biosecurity practices were assessed. Quarantine, culling, carcass disposal, and disinfection were implemented. Results: ASF virus genotype I was detected. A concurrent ASF outbreak in neighbouring Mpumalanga Province was identified as a possible source. Inadequate biosecurity measures probably facilitated viral transmission. Potential mechanisms for the introduction of the ASF virus include swill feeding practices, free roaming of pigs, scavenging, illegal slaughter, and trade of pig products within the community. Conclusions: Molecular typing of the ASF virus linked the outbreak to an ongoing ASF outbreak in Mpumalanga Province. Pig enterprises with poor biosecurity practices may face greater risk of ASF introduction. Small-scale pig keepers should be targeted for ASF awareness and education campaigns. Innovative and cost-effective biosecurity solutions are needed in this resource-poor setting. (C) 2021 The Author(s). Published by Elsevier Ltd on behalf of International Society for Infectious Diseases.

Automated summary

An outbreak of African swine fever (ASF) in a small-scale pig unit in Gauteng Province was linked to a neighboring ASF outbreak in Mpumalanga Province through molecular typing. Inadequate biosecurity measures may have facilitated viral transmission, highlighting the importance of targeted ASF awareness and education campaigns for small-scale pig keepers. Innovative and cost-effective biosecurity solutions are needed in resource-limited settings to prevent future outbreaks.