Thomson, G R, Tambi, E N, Hargreaves, S K, Leyland T J, Catley A P, van’t Klooster, G G M & Penrith, M-L, (2004). International trade in livestock and livestock products: The need for a commodity-based approach. The Veterinary Record (2004) 155,429-433
Summary
International animal health standards designed to facilitate safe trade in livestock and livestock products are set by the Office International des Epizooties (OIE) under the Sanitary and Phytosanitary Agreement of the World Trade Organization (WTO) and documented in the OIE’s Terrestrial Animal Health Code (the Code). A core principle of the Code is the need for countries to eradicate important transboundary animal diseases (TADs) to reduce the risk of exporting disease to trading partners. International food safety standards are set by the Codex Alimentarius Commission, administered jointly by the World Health Organization and the Food and Agriculture Organization.The goal of global eradication of most TADs is unachievable for the foreseeable future, other than in the case of rinderpest, and this prevents many countries from engaging in international trade under WTO rules, especially developing nations. An alternative commodity-based approach is proposed to the formulation of international animal health and food safety standards based on the fact that different commodities pose very different risks when it comes to spread of human and animal pathogens. Therefore, the risk mitigation strategies required are equally commodity dependent. We conclude that more focused commodity standards would improve access to international markets for all countries, especially those in the developing world. For this objective to be realized, credible and independent certification is required.
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Penrith , M-L, Thomson G R, Bastos, A D S, Phiri O C, Lubisi B A, Du Plessis E C, Macome, F, Pinto F, Botha B & Esterhuysen J, (in press). An investigation into natural resistance to African swine fever in domestic pigs from an endemic area in southern Africa. OIE Scientific and technical Review.
Summary
A population of domestic pigs in northern Moçambique with increased resistance to the pathogenic effects of African swine fever (ASF) virus was identified by the high prevalence of circulating antibodies to ASF virus. An attempt was made to establish whether the resistance in this population was heritable. Some of these pigs were acquired and transported to a quarantine facility and allowed to breed naturally. Offspring of the resistant pigs were transferred to a high security facility where they were challenged with two ASF viruses, one of which was isolated from the population of pigs from which the Mocambiquan pigs were derived and the other a genetically closely-related virus from Madagascar. All but one of the 105 offspring challenged developed acute ASF and died. It therefore appears that the resistance demonstrated by these pigs is not inherited by their offspring, or could not be expressed under the conditions of the experiment. The question remains therefore as to the mechanism whereby pigs in the population from which the experimental pigs were derived co-existed with virulent ASF viruses.

Bastos, A D S, Penrith M-L, Crucière C, Edrich J L, Hutchings G, Roger, F, Couacy-Hymann, E & Thomson G R, 2003. Genotyping field strains of African swine fever virus by partial p72 gene characterization. Archives of Virology, 148, 693-706.
Summary
A PCR sequencing method was developed which permits detection and characterization of African swine fever virus (ASFV) variants within 5 and 48h, respectively, of receipt of a clinical specimen. Amplification of a 478 bp fragment corresponding to the C-terminal end of the p72 gene confirms virus presence with gene characterization being achieved by nucleotide sequence determination and phylogenetic analysis. The method was applied to 55 viruses including those representative of the major ASF lineages identified previously by restriction fragment length polymorphism (RFLP) analysis. Results confirmed that the p72 method identifies the same major viral groupings. Characterization of additional viruses of diverse geographical, species and temporal origin using the PCR-based method indicated the presence of 10 major ASF genotypes on the African continent, the largest of which comprised a group of genetically homogeneous viruses recovered from outbreaks in Europe, South America, the Caribbean and West Africa (the ESAC-WA genotype). In contrast viruses from southern and eastern African countries were heterogeneous with multiple genotypes being present within individual countries. This study provides a rapid and accurate method of determining the genotype of field and outbreak strains of ASF and is therefore useful for molecular epidemiological clarification of ASF.

Thomson G R, Vosloo W & Bastos A D S, (2003). Foot and mouth disease in wildlife. Virus Research, 91, 145-161.
No published summary. Thomson G, Dungu B, Tounkara K, Vosloo W, Bastos A. & Bidjeh K, 2003. Suitability of currently available vaccines for controlling the major transboundary diseases that afflict sub-Saharan Africa. In: Vaccines for List A and Emerging Animal Diseases. Brown, F. & Roth, J. (eds), 114, 229-241. Karger: Basel.
No published summary.

Bastos A D S., Haydon D T, Sangare O, Boshoff C I, Edrich J L & Thomson G R (2003). The implications of viral diversity within the SAT-2 serotype for control of foot-and-mouth disease in sub-Saharan Africa. Journal of General Virology, 84, 1595-1606.
Summary
SAT 2 is the serotype most often associated with outbreaks of foot-and-mouth disease (FMD) in livestock in southern and western Africa and is the only SAT type to have been recorded outside the African continent in the last decade. Its epidemiology is complicated by the presence of African buffalo (Syncerus caffer), which play an important role in virus maintenance and transmission. To assess the level of genetic complexity of this serotype among viruses associated with both domestic livestock and wildlife, complete VP1 gene sequences for 53 viruses from 17 countries and three different host species were analysed. Phylogenetic analysis revealed eleven virus lineages, differing from each other by at least 20% in pairwise nucleotide comparisons, four of which fall within the southern African region, two in West Africa and the remaining 5 in central and East Africa. No evidence of recombination between these lineages was detected, and thus we conclude that these are independently evolving virus lineages which occur primarily in discrete geographical localities in accordance with the FMD virus topotype concept. Applied to the whole phylogeny, rates of nucleotide substitution are significantly different between topotypes, but most individual topotypes evolve in accordance with a molecular clock at an average rate of approximately 0.002 substitutions per site per year. This study provides an indication of the intratypic complexity of the SAT 2 serotype at the continental level and emphasizes the value of molecular characterization of diverse FMD field strains for tracing the origin of outbreaks.

Thomson G R, Bengis R G & Brown C (2001). Picornaviruses. In: Infectious Diseases of Wild Mammals, 3rd Edn., E.S. Williams & I.K. Barker (eds.), pp 119-130, Iowa University Press: Ames, USA.
No summary published.

Scott Wilson Resource Consultants, 2000. Environmental impact assessment of the veterinary fences in Ngamiland. Six volume report plus a summary report for the Government of Botswana. Study jointly funded by the Department for International Development (UK) and the Government of Botswana.Full publication lists available on request