Detection of African swine fever virus in the tissues of asymptomatic pigs in smallholder farming systems along the Kenya-Uganda border: implications for transmission in endemic areas and ASF surveillance in East Africa.

The persistence of African swine fever virus (ASFV) in endemic areas, with small-scale but regular outbreaks in domestic pigs, is not well understood. ASFV has not been detected using conventional diagnosis in these pigs or adjacent populations of resistant African wild pigs, that could act as potential carriers during the outbreaks. However, such data are crucial for the design of evidence-based control strategies. We conducted cross-sectional (1107 pigs) and longitudinal (100 pigs) monitoring of ASFV prevalence in local pigs in Kenya and Uganda. The horizontal survey revealed no evidence of ASFV in the serum or blood using either conventional or real-time PCR. One pig consistently tested positive using ELISA, but negative using PCR assays on blood. Interestingly, the isotype of the antibodies from this animal were strongly IgA biased relative to control domestic pigs and warthogs, suggesting a role for mucosal immunity. The tissues from this pig were positive by PCR following post-mortem. Internal organ tissues of 44 healthy pigs (28 sentinel pigs and 16 pigs from slaughter slabs) were tested with four different PCR assays; 15.9 % were positive for ASFV suggesting that healthy pigs carrying ASFV exist in the swine population in the study area. P72 and p54 genotyping of ASFV revealed very limited diversity: all were classified in genotype IX at both loci, as were virtually all viruses causing recent ASF outbreaks in the region. Our study suggests that carrier pigs may play a role in ASF disease outbreaks, although the triggers for outbreaks remain unclear and require further investigation. This study significantly increases scientific knowledge of the epidemiology of ASF in the field in Africa, which will contribute to the design of effective surveillance and control strategies.

Pig traders' networks on the Kenya-Uganda border highlight potential for mitigation of African swine fever virus transmission and improved ASF disease risk management.

We applied social network analysis to pig trader networks on the Kenya-Uganda border. Social network analysis is a recently developed tool, which is useful for understanding value chains and improving disease control policies. We interviewed a sample of 33 traders about their experiences with trade and African swine fever (ASF), analyzed the networks they generated in purchasing pigs and selling pork and their potential contribution to modulating dissemination of the ASF virus (ASFV). The majority of the traders were aware of clinical signs of ASF and the risk of trade transmitting ASFV. Most said they avoided buying pigs from ASF outbreak villages or sick pigs but their experiences also indicated that inadvertent purchase was relatively common. Traders had early knowledge of outbreaks since they were contacted by farmers who had heard rumours and wanted to sell their pigs to avoid the risk of them dying. Individual traders bought pigs in up to nine villages, and up to six traders operated in a village. Although each trade typically spanned less than 5km, networks of the various traders, comprising movements of pigs from source villages to slaughter slabs/sites and retail outlets, and movement of pork to villages where it was consumed, linked up indirectly across the 100km×50km study area and revealed several trade pathways across the Kenya-Uganda border. ASF could potentially spread across this area and beyond through sequential pig and pork transactions. Regulation of the pig and pork trade was minimal in practice. The risk of ASFV being spread by traders was compounded by their use of poorly constructed slaughter slabs/sites with open drainage, ineffective or non-existent meat inspection services, lack of provision for biosecurity in the value chain, and sales of pork to customers who were unaware of the risks to their own pigs from contact with ASF infected pork. More effective regulation is warranted. However, limitations on government capacity, together with the strong self-interest that established traders have in reducing the disruption and financial losses that outbreaks cause, highlight the importance of governments and traders co-developing an approach to ASF control. Formation of trader organizations or common interest groups warrants government support as an important step in engaging traders in developing and implementing effective approaches to reduce the risk of ASF outbreaks.

Enhancing knowledge and awareness of biosecurity practices for control of African swine fever among smallholder pig farmers in four districts along the Kenya-Uganda border.

A study was undertaken along the Kenya-Uganda border in four districts of Tororo and Busia (Uganda) and Busia and Teso (Kenya) to understand smallholder farmers' knowledge, practices and awareness of biosecurity measures. Information was collected by administering questionnaires to 645 randomly selected pig households in the study area. In addition, focus group discussions were carried out in 12 villages involving 248 people using a standardized list of questions. The outcome suggested that there was a very low level of awareness of biosecurity practices amongst smallholder farmers. We conclude that adoption of specific biosecurity practices by smallholder farmers is feasible but requires institutional support. There is a clear requirement for government authorities to sensitize farmers using approaches that allow active participation of farmers in the design, planning and implementation of biosecurity practices to enable enhanced adoption.

Social network analysis provides insights into African swine fever epidemiology.

Pig movements play a significant role in the spread of economically important infectious diseases such as the African swine fever. Characterization of movement networks between pig farms and through other types of farm and household enterprises that are involved in pig value chains can provide useful information on the role that different participants in the networks play in pathogen transmission. Analysis of social networks that underpin these pig movements can reveal pathways that are important in the transmission of disease, trade in commodities, the dissemination of information and the influence of behavioural norms. We assessed pig movements among pig keeping households within West Kenya and East Uganda and across the shared Kenya-Uganda border in the study region, to gain insight into within-country and trans-boundary pig movements. Villages were sampled using a randomized cluster design. Data were collected through interviews in 2012 and 2013 from 683 smallholder pig-keeping households in 34 villages. NodeXL software was used to describe pig movement networks at village level. The pig movement and trade networks were localized and based on close social networks involving family ties, friendships and relationships with neighbours. Pig movement network modularity ranged from 0.2 to 0.5 and exhibited good community structure within the network implying an easy flow of knowledge and adoption of new attitudes and beliefs, but also promoting an enhanced rate of disease transmission. The average path length of 5 defined using NodeXL, indicated that disease could easily reach every node in a cluster. Cross-border boar service between Uganda and Kenya was also recorded. Unmonitored trade in both directions was prevalent. While most pig transactions in the absence of disease, were at a small scale (<5km) and characterized by regular agistment, most pig sales during ASF outbreaks were to traders or other farmers from outside the sellers' village at a range of >10km. The close social relationships between actors in pig movement networks indicate the potential for possible interventions to develop shared norms and mutually accepted protocols amongst smallholder pig keepers to better manage the risk of ASF introduction and transmission.

Risk factors associated with occurrence of African swine fever outbreaks in smallholder pig farms in four districts along the Uganda-Kenya border.

A cross-sectional survey was carried out to assess risk factors associated with occurrence of African swine fever (ASF) outbreaks in smallholder pig farms in four districts along Kenya-Uganda border. Information was collected by administering questionnaires to 642 randomly selected pig households in the study area. The study showed that the major risk factors that influenced ASF occurrence were purchase of pigs in the previous year (p < 0.000) and feeding of pigs with swill (p < 0.024). By employing cluster analysis, three clusters of pig production types were identified based on production characteristics that were found to differ significantly between districts. The most vulnerable cluster to ASF was households with the highest reported number of ASF outbreaks and composed of those that practiced free range at least some of the time. The majority of the households in this cluster were from Busia district in Uganda. On the other hand, the least vulnerable cluster to ASF composed of households that had the least number of pig purchases, minimal swill feeding, and less treatment for internal and external parasites. The largest proportion of households in this cluster was from Busia district Kenya. The study recommended the need to sensitize farmers to adopt proper biosecurity practices such as total confinement of pigs, treatment of swill, isolation of newly purchased pigs for at least 2 weeks, and provision of incentives for farmers to report suspected outbreaks to authorities and rapid confirmation of outbreaks.

Facilitating complementary inputs and scoping economies in the joint supply of health and environmental services in Aboriginal central Australia.

Two concerns of national relevance in central Australia are the continuing decline in Aboriginal health status relative to the rest of the Australian population, and the loss of environmental services. We draw on literature from a number of disciplines to show that not only are these two concerns interrelated but that dealing with them is inextricably connected through consideration of the psychosocial determinants of health. Involvement by Aboriginal people in land management can promote the joint supply of environmental and health services. We show that Aboriginal control of land management can result in economies through the joint supply of environmental and health services. However, because Aboriginal people derive little benefit from the provision of public goods generated through land management, they have little incentive to provide a socially optimal supply of these goods. The policy issue for government is the selection of the appropriate policy tools to facilitate the involvement of Aboriginal people in land management and the optimal supply of health and environmental services. The cost-effectiveness plane is used to provide a simple framework to guide the selection of an appropriate policy tool.

Genomic polymorphism at the interferon-induced helicase (IFIH1) locus contributes to Graves' disease susceptibility.

CONTEXT: A recent large-scale analysis of nonsynonymous coding polymorphisms showed strong evidence that an alanine to threonine amino acid change at codon 946 of the interferon-induced helicase (IFIH1) gene (SNP ID rs1990760) was associated with type 1 diabetes. Previous investigations have also demonstrated that an intronic polymorphism (termed PD1.3; SNP ID rs11568821) in the programmed cell death (PDCD1) gene was associated with systemic lupus erythematosus and rheumatoid arthritis. OBJECTIVE: We sought to replicate these genetic associations in Graves' disease and autoimmune Addison's disease patient cohorts. PATIENTS AND METHODS: A total of 602 Graves' disease subjects, 214 Addison's disease subjects, and 446 healthy controls were genotyped for the IFIH1 and PDCD1 single-nucleotide polymorphisms using mass spectrometer analysis of primer extension products (Sequenom). RESULTS: The alanine-carrying allele at the IFIH1 codon 946 polymorphism was present in 796 of 1204 (66%) Graves' disease patient alleles compared with 508 of 892 (57%) control subject alleles [odds ratio 1.47 (5-95% confidence interval, 1.23-1.76); P = 1.9 x 10(-5)]. In contrast, there was no association of alleles at this marker in autoimmune Addison's disease. Neither was there evidence for association in either patient cohort at the PD1.3 polymorphism. CONCLUSIONS: We confirm a significant contribution of the Ala946Thr IFIH1 polymorphism to organ-specific autoimmune diseases, extending the range of conditions associated with this variant to include Graves' disease. This polymorphism may also contribute to several other autoimmune disorders.