title: African swine fever outbreak on a medium-sized farm in Uganda: biosecurity breaches and within-farm virus contamination.
abstract: In Uganda, a low-income country in east Africa, African swine fever (ASF) is endemic with yearly outbreaks. In the prevailing smallholder subsistence farming systems, farm biosecurity is largely non-existent. Outbreaks of ASF, particularly in smallholder farms, often go unreported, creating significant epidemiological knowledge gaps. The continuous circulation of ASF in smallholder settings also creates biosecurity challenges for larger farms. In this study, an on-going outbreak of ASF in an endemic area was investigated on farm level, including analyses of on-farm environmental virus contamination. The study was carried out on a medium-sized pig farm with 35 adult pigs and 103 piglets or growers at the onset of the outbreak. Within 3 months, all pigs had died or were slaughtered. The study included interviews with farm representatives as well as biological and environmental sampling. ASF was confirmed by the presence of ASF virus (ASFV) genomic material in biological (blood, serum) and environmental (soil, water, feed, manure) samples by real-time PCR. The ASFV-positive biological samples confirmed the clinical assessment and were consistent with known virus characteristics. Most environmental samples were found to be positive. Assessment of farm biosecurity, interviews, and the results from the biological and environmental samples revealed that breaches and non-compliance with biosecurity protocols most likely led to the introduction and within-farm spread of the virus. The information derived from this study provides valuable insight regarding the implementation of biosecurity measures, particularly in endemic areas.
authors.affiliation: National Veterinary Institute, Uppsala, Sweden. erika.chenais@sva.se.|Swedish University of Agricultural Sciences, Uppsala, Sweden. erika.chenais@sva.se.
authors.forename: Erika
authors.identifier: http://orcid.org/0000-0002-2601-1256
authors.initials: E
authors.lastname: Chenais
authors.affiliation: Swedish University of Agricultural Sciences, Uppsala, Sweden.
authors.forename: Susanna
authors.initials: S
authors.lastname: Sternberg-Lewerin
authors.affiliation: Swedish University of Agricultural Sciences, Uppsala, Sweden.
authors.forename: Sofia
authors.initials: S
authors.lastname: Boqvist
authors.affiliation: National Veterinary Institute, Uppsala, Sweden.
authors.forename: Lihong
authors.initials: L
authors.lastname: Liu
authors.forename: Neil
authors.initials: N
authors.lastname: LeBlanc
authors.affiliation: Directorate of Production and Marketing, Gulu District Local Government, Gulu, Uganda.
authors.forename: Tonny
authors.initials: T
authors.lastname: Aliro
authors.affiliation: Makerere University, Kampala, Uganda.
authors.forename: Charles
authors.initials: C
authors.lastname: Masembe
authors.affiliation: National Veterinary Institute, Uppsala, Sweden.|Swedish University of Agricultural Sciences, Uppsala, Sweden.
authors.forename: Karl
authors.initials: K
authors.lastname: Ståhl
mesh_terms: D000357:African Swine Fever / Q000453:epidemiology* / Q000517:prevention & control / Q000635:transmission / Q000821:virology; D000358:African Swine Fever Virus / Q000302:isolation & purification*; D000822:Animal Husbandry; D000818:Animals; D004196:Disease Outbreaks / Q000662:veterinary*; D000072480:Farms; D005260:Female; D008297:Male; D012637:Security Measures; D013552:Swine; D014454:Uganda / Q000453:epidemiology
keywords: Environmental contamination; Environmental sampling; Farm biosecurity; Infectious disease outbreak; Smallholders