Epidemiological Overview of African Swine Fever in Uganda (2001–2012)

Abstract

African swine fever (ASF) is a contagious viral disease, which can cause up to 100% mortality among domestic pigs. In Uganda there is paucity of information on the epidemiology of the disease, hence a study was carried out to elucidate the patterns of ASF outbreaks. Spatial and temporal analyses were performed with data collected monthly by the district veterinary officers (DVOs) and sent to the central administration at MAAIF from 2001 to 2012. Additionally, risk factors and the associated characteristics related to the disease were assessed based on semistructured questionnaires sent to the DVOs. A total of 388 ASF outbreaks were reported in 59 districts. Of these outbreaks, 201 (51.8%) were reported in districts adjacent to the national parks while 80 (20.6%) were adjacent to international borders. The number of reported ASF outbreaks changed over time and by geographical regions; however, no outbreak was reported in the North-Eastern region. ASF was ranked as second most important disease of pigs, and it occurred mostly during the dry season (P = 0.01). Pig movements due to trade (OR 15.5, CI 4.9–49.1) and restocking (OR 6.6, CI 2.5–17.3) were the major risk factors. ASF control strategies should focus on limiting pig movements in Uganda.

African swine fever: A re-emerging viral disease threatening the global pig industry

“…Virus can persist for prolonged periods in tissues or blood from recovered pigs or following infection with low virulence isolates, which might contribute to virus transmission, disease persistence, sporadic outbreaks and ASFV introduction into disease-free zones ( Penrith and Vosloo, 2009 , Costard et al, 2013 , Gallardo et al, 2015 ). Recent studies in Africa have identified ASFV sequences in apparently healthy pigs in Uganda ( Kalenzi Atuhaire et al, 2013 ) and Kenya ( Thomas et al, 2016 ), suggesting that reduced virulence isolates may be circulating in these regions. There is limited experimental evidence for transmission from persistently infected to naïve animals.…”

Analysis of pig trading networks and practices in Uganda

“…Penrith and Vosloo reported that outbreaks of ASF in new areas of Africa have almost all been associated with movement of domestic pigs and pig products (Penrith and Vosloo 2009). In Uganda, several studies to characterize practices associated with the occurrence and spread of ASF identified the collection of pigs and pig products from farms (Kabuuka et al 2014), distribution of infected pork by traders , pig movements due to restocking and trade (Kalenzi Atuhaire et al 2013;Nantima et al 2015), free range movement of pigs on farms (Nantima et al 2015) and trade of live pigs and pig products (Tejler and Teijler 2012) as risk factors. These studies focused on pig farmers and their perception of trading and pig movements.…”

Regional level risk factors associated with the occurrence of African swine fever in West and East Africa

“…Higher human population density, which was used as the surrogate of trade activity [41, 42], may also facilitate ASF spread. In fact, pig movement and trade activity have been considered as important factors for ASF spread, especially in West Africa where the domestic cycle is dominated [10, 11, 17]. As expected, no wild suids showed a significant relationship with ASF occurrence, suggesting that the sylvatic cycle may not play an important role in ASF transmission at regional scales in West Africa.…”