Animal husbandry practices and livestock movements are some of the main factors that increase the risk of disease introduction and spread. This knowledge is particularly relevant in transboundary areas to anticipate and prevent the introduction of transboundary animal diseases. In South Africa, the management of some notifiable livestock diseases is based on the establishment of disease control zones in line with the recommendations of the World Animal Health Organization (OIE). Movement between these zones is controlled by local, provincial, and national veterinary authorities. Because disease occurrence and spread is a dynamic process, it is important to ensure that infected livestock are not exported from areas delineated as disease protection or control zones. In this study, 254 pig farmers were interviewed to gather information on the local socio-economic importance of pig farming, the pig husbandry methods employed and the movement of pigs within and outside the African swine fever (ASF) control zone from Northern Kwa Zulu Natal. In addition, blood samples taken from 174 domestic pig of those farms were tested for ASF antibodies. Social network analysis of data collected showed an extensive trade network without the involvement of intermediaries and sporadic exchanges with neighbouring communities, including some located in Mozambique and Eswatini. The maximum distance travelled for selling pigs was 495 km. Husbandry methods (free ranging pigs, throwing away carcass offal and slaughtering remains at homesteads) implemented by the farmers, predominantly single women, increased the risks of disease introduction and transmission. Considering the importance of subsistence pig farming in the study area, especially to women, and despite the absence of ASF antibodies in sampled pigs, it is highly relevant to educate the community and raise awareness on the risk implications of uncontrolled trade in pigs and poor husbandry practices in transboundary disease introduction and transmission.

Pig outdoor farming is gaining popularity and commercial success in the EU and its expansion, together with an increasingly abundance of wild boar populations facilitates interactions between domestic and wild suids. In the Southern French Department of Ardèche, several episodes of mass mortalities due to infection with an enteropathogenic strain of Escherichia coli, causing oedema disease (OD) were reported in wild boar populations between 2013 and 2016. In order to investigate a potential link between those events and the frequency of interactions between wild boar and domestic pigs, we analysed regional vegetation and hunting bag data and implemented a semi-structured questionnaire survey among a total of 30 outdoor pig farmers and 30 hunters distributed inside and outside the identified area of OD emergence. One third of interviewed farmers (11/30) had experienced intrusions of wild boars in domestic pig premises during the previous year. Similarly, 23% of interviewed hunters reported interactions between wild boar and feral free ranging pigs in recent years and 60% reported the observation of free ranging pigs with a phenotypic feature of Vietnamese pot-bellied pigs (55%). Our analysis identified that the OD emergence area gathered several factors that could facilitate interactions between wild and domestic suids including a predominance of forested vegetation, a higher estimated wild boar density, weaker levels of farm biosecurity and a higher level of reported intrusions or interactions with wild boar in pig farms. Despite our sample was limited, our study suggests that the occurrence and dissemination of wild domestic suid interactions in this region might be higher than expected and sufficient to facilitate the circulation of shared pathogens between wild and domestic suids. Similar studies in this and other rural regions in the EU are recommended, in order to identify risk areas and anticipate preparedness for the emergence and circulation of shared swine pathogens.

In Southern Africa, the African Swine Fever (ASF) sylvatic cycle presents a permanent threat for the development of the pig farming industry. Warthogs (Phacochoerus africanus) and bushpigs (Potamochoerus larvatus), wild reservoirs of ASF are present in Ndumo Game Reserve (NGR), located in Northern KwaZulu Natal Province in South Africa and within 30 km of the locations of endemic ASF outbreaks in Mozambique where sylvatic disease transmission has been implicated. To assess if wild suids represent a risk of ASF virus spillover to domestic pigs in the neighbouring community, transect counts and fence patrols were conducted and camera traps were deployed in NGR to estimate wild suid abundance and incursions outside NGR boundaries. We searched for Ornithodoros ticks in 35 warthog burrows distributed across different NGR areas. Pig farmers (n=254) surrounding Mathenjwa Community were interviewed to gather information on interactions between domestic and wild suids and the occurrence of ASF. We conclude that NGR has established populations of bushpigs and warthogs, estimated at 5 and 3-5 individuals/km2 respectively. Both species move out of the reserve regularly (15.4 warthogs/day and 6.35 bushpigs/day), with a significant increase of movements during the dry season. Some farmers observed warthogs and bushpigs as far as 8 and 19 km from the reserve respectively, but no direct wild-domestic suids interactions nor any ASF outbreaks were reported. In addition, no soft ticks were found among the 35 warthog burrows. The absence of ticks in warthog burrows from NGR and the absence of reported outbreaks and familiarity with ASF in the surrounding farming area, suggest that a sylvatic cycle of ASF is at present unlikely in NGR. However, further research should be undertaken to confirm this by surveying a larger number of warthog burrows and monitoring potential antibodies in warthogs from NGR and domestic pigs in the neighbouring community.