Drivers and risk factors for circulating African swine fever virus in Uganda, 2012-2013

We explored observed risk factors and drivers of infection possibly associated with African swine fever (ASF) epidemiology in Uganda. Representative sub-populations of pig farms and statistics were used in a case-control model. Indiscriminate disposal of pig viscera and waste materials after slaughter, including on open refuse dumps, farm-gate buyers collecting pigs and pig products from within a farm, and retention of survivor pigs were plausible risk factors. Wire mesh-protected windows in pig houses were found to be protective against ASF infection. Sighting engorged ticks on pigs, the presence of a lock for each pig pen and/or a gate at the farm entrance were significantly associated with infection/noninfection; possible explanations were offered. Strict adherence to planned within-farm and communitybased biosecurity, and avoidance of identified risk factors is recommended to reduce infection. Training for small-scale and emerging farmers should involve multidimensional and multidisciplinary approaches to reduce human-related risky behaviours driving infection.National Agricultural Research Organization (NARO) (4760UG) and the Department of Production Animal Studies and the Faculty of Veterinary Science, Onderstepoort, Pretoria, South Africa.http://www.elsevier.com/locate/rvsc2015-10-31hb201

Retrospective multi-locus sequence analysis of African swine fever viruses by “PACT” confirms co-circulation of multiple outbreak strains in Uganda

This article belongs to the Special Issue titled 'African Swine Fever Virus Transmission and Control: The Role of Wild and Domestic Suids'.SUPPORTING INFORMATION: FILE S1: Supplementary Materials: The following supporting information can be downloaded at: https://www.mdpi.com/article/10.3390/ani14010071/s1, Figures S1–S4: Figure S1: Agarose gel electrophoresis of p72-PCR products amplified with P1 and P2 OIE p72 screening primers (Lane m: 100 bp ladder; lane N: Negative control; lane P: Positive control; lanes 10, 36, 46, 48, 52, 58 and 59; Positive amplicons (n = 7)); Figure S2: Agarose gel electrophoresis of p54 [A], CVR-ORF [C], p72 [P] and Tk [T] gene cycle sequenced products using modified reaction conditions and demonstrating improved TK gene amplification (Lanes L = 100 bp ladder; N = Negative control; A1, P1, P6, T1, T2, T3, T4, T6 and T7 are positive amplicons from purified DNA products. The figure showed that agarose gel bands for positive cycle sequenced products are evident in lanes in A1, P1, P6, T1, T2, T3, T4, T6 and T7. Figure 3 shows the second PCR results in lanes A2, A6, A7, C1, C2, C5, C6, C7, P1, P2, P5, P6, P7, T2, T5, T6 and T7); Figure S3: Agarose gel electrophoresis of p54 [A], CVR-ORF [C], p72 [P] and Tk [T] gene products (Lanes L = 100 bp ladder; N = Negative control; A2, A6, A7, C1, C2, C5, C6, C7, P1, P2, P5, P6, P7, T2,T5, T6 and T7 are positive amplicons from purified DNA products); Figure S4: Agarose gel electrophoresis of TK gene-PCR products amplified with TK-1 + TK-Rev primers (Lane L = 100 bp ladder; N = Negative control; P1= Positive control; 2, 15 and 17 are new Tk gene positive amplicons).DATA AVAILABILITY STATEMENT : All supporting data used in this research are freely available as Supplementary Materials or at the UPeTD (https://repository.up.ac.za/handle/2263/31741, accessed on 15 December 2023). All sequence data are available in the manuscript with their Accession numbers.African swine fever (ASF) is a haemorrhagic fever of swine that severely constrains pig production, globally. In Uganda, at least 388 outbreaks of ASF were documented from 2001 to 2012. We undertook a retrospective serological and molecular survey of ASF virus (ASFV) using banked samples collected from seven districts (Pallisa, Lira, Abim, Nebbi, Kabarole, Kibaale, and Mukono) of Uganda. Six assays (ELISA for antibody detection, diagnostic p72 gene PCR and genomic amplification, and sequencing of four gene regions (p72 [P], p54 [A], CVR of the 9RL-ORF [C], and TK [T]), hereinafter referred to as P-A-C-T (PACT)) were evaluated. Antibodies to ASFV were detected in the Abim district (6/25; 24.0%), and the remainder of the serum samples were negative (187/193; 96.9%). For the tissue samples, ASFV detection by assay was 8.47% for P, 6.78% for A, 8.47% for C, and 16.95% for T. The diagnostic PCR (p72 gene) detected seven positive animals from four districts, whereas the TK assay detected ten positives from all seven districts. In addition to the superior detection capability of TK, two virus variants were discernible, whereas CVR recovered three variants, and p72 and p54 sequencing each identified a single variant belonging to genotype IX. Our results indicate that dependence on serology alone underestimates ASF positivity in any infected region, that multi-locus sequence analysis provides better estimates of outbreak strain diversity, and that the TK assay is superior to the WOAH-prescribed conventional p72 diagnostic PCR, and warrants further investigation.The National Agricultural Research Organization, Uganda, through Government of Uganda; The World Bank-ATAAS scholarship; The University of Pretoria Postgraduate scholarship; NRF incentive funding; the National Research Foundation (NRF)https://www.mdpi.com/journal/animalsProduction Animal StudiesVeterinary Tropical DiseasesZoology and EntomologySDG-03:Good heatlh and well-bein

Drivers and risk factors for circulating African swine fever virus in Uganda, 2012–2013

We explored observed risk factors and drivers of infection possibly associated with African swine fever (ASF) epidemiology in Uganda. Representative sub-populations of pig farms and statistics were used in a case-control model. Indiscriminate disposal of pig viscera and waste materials after slaughter, including on open refuse dumps, farm-gate buyers collecting pigs and pig products from within a farm, and retention of survivor pigs were plausible risk factors. Wire mesh-protected windows in pig houses were found to be protective against ASF infection. Sighting engorged ticks on pigs, the presence of a lock for each pig pen and/or a gate at the farm entrance were significantly associated with infection/noninfection; possible explanations were offered. Strict adherence to planned within-farm and communitybased biosecurity, and avoidance of identified risk factors is recommended to reduce infection. Training for small-scale and emerging farmers should involve multidimensional and multidisciplinary approaches to reduce human-related risky behaviours driving infection.National Agricultural Research Organization (NARO) (4760UG) and the Department of Production Animal Studies and the Faculty of Veterinary Science, Onderstepoort, Pretoria, South Africa.http://www.elsevier.com/locate/rvsc2015-10-31hb201