Mary-Louise Penrith

African swine fever virus eradication in Africa

African swine fever was reported in domestic pigs in 26 African countries during the period 2009-2011. The virus exists in an ancient sylvatic cycle between warthogs (Phacochoerus africanus) and argasid ticks of the Ornithodoros moubata complex in many of the countries reporting outbreaks and in two further countries in the region. Eradication of the virus from the countries in eastern and southern Africa where the classic sylvatic cycle occurs is clearly not an option. However, the virus has become endemic in domestic pigs in 20 countries and the great majority of outbreaks in recent decades, even in some countries where the sylvatic cycle occurs, have been associated with movement of infected pigs and pig meat. Pig production and marketing and ASF control in Africa have been examined in order to identify risk factors for the maintenance and spread of ASF. These include large pig populations, traditional free-range husbandry systems, lack of biosecurity in semi-intensive and intensive husbandry systems, lack of organisation in both pig production and pig marketing that results in lack of incentives for investment in pig farming, and ineffective management of ASF. Most of these factors are linked to poverty, yet pigs are recognised as a livestock species that can be used to improve livelihoods and contribute significantly to food security. The changes needed and how they might be implemented in order to reduce the risk of ASF to pig producers in Africa and to the rest of the world are explored.

Classical swine fever (Hog cholera) : review of aspects relevant to control

Classical swine fever (CSF) has the ability to spread over large distances when human intervention such as illegal swill feeding facilitates its movement. This was apparent during 2005 when CSF appeared in South Africa (SA) after an absence of 87 years. In this review, various newly published developments in terms of the diagnosis of the disease and vaccination are described and applied to situations similar to SA. The role of wildlife such as feral pigs and European wild boar in the dissemination and maintenance of CSF virus are discussed, and the dearth of knowledge on the potential of other wild pig species prevalent on southern Africa noted. The modes of spread and control measures to prevent introduction as well as during outbreaks are discussed.

Balancing Livestock Production and Wildlife Conservation in and around Southern Africa's Transfrontier Conservation Areas

Biodiversity conservation, of which the transfrontier conservation area movement is an integral part, and more effective livestock production/trade are pivotal to future rural development in southern Africa. For that reason, it is imperative to effectively ameliorate the obstacles that have impeded progress towards the coexistence of these two sectors for more than half a century. Transboundary animal diseases, foot and mouth disease in particular, have been and continue to be the most important of these obstacles. Fortunately, new developments in international sanitary standards applicable to trade in commodities and products derived from animals are beginning to make a solution possible. However, while progress in principle has been achieved, practical implementation remains problematic for technical reasons, exacerbated by inconsistent attitudes towards acceptance of non-traditional international trade standards. This paper describes the background to this situation, progress that has been achieved in the recent past and remaining difficulties that need to be overcome to advance towards achievement of balanced rural development in southern Africa.

Intra- and inter-genotypic size variation in the central variable region of the 9RL open reading frame of diverse African swine fever viruses.

African swine fever (ASF) viruses are characterised by numerous p72 genotypes, but by low levels of intra-genotypic variation, particularly in domestic pig associated genotypes. As it is precisely these viral lineages that are involved in outbreaks of the disease it is imperative that alternative, more informative gene regions be identified which are suitable for intra-genotypic resolution of relationships. To this end, the central variable region (CVR) of the 9RL open reading frame of diverse ASF viruses was amplified and product sizes scored and compared within and between genotypes. Results indicate that although product sizes are not genotype restricted, there is a high degree of intra-genotypic size variation particularly within the homogeneous p72 genotypes. Within one such genotype, the ESACWA virus genotype, 12 size-discrete CVR products were identified, four corresponding to viruses of west African origin and eight to viruses from countries where the disease is exotic, namely Europe, South America and the Caribbean. The high degree of size heterogeneity in the CVR of this genotype is significant and attests to the usefulness of the CVR gene marker in elucidating the epidemiology of African swine fever.

Has culling been properly assessed as a valid and justified control intervention measure for zoonotic diseases

In their PLoS Neglected Tropical Diseases research article “A Pilot Study for Control of Hyperendemic Cystic Hydatid Disease in China,” Zhang et al. [1] describe a research project conducted from 1987 to 1994 in Xinjiang, a multiethnic and multireligious province in western China. The study aimed to assess the efficacy and cost-effectiveness of applying monthly praziquantel treatment to dogs on the prevalence of hydatid disease in sheep. As a part of the study a large number of dogs were caught and killed. The approach described in the paper leaves the reader with a number of dilemmas regarding ethics, validity of the research, and research ethical questions. Culling animals has been used in many parts of the world as a highly effective way to control and eliminate various infectious diseases of both veterinary and human health importance [2]. Enforcement has been a necessary component as many animal owners do not necessarily agree to this utilitarian approach at the expense of their animal, especially if the animal is not apparently ill or suffering. Regardless of enforcement, if market-level compensation is not paid to owners of animals compulsorily slaughtered, illegal movements may occur and the disease can spread faster and last longer as a result [3]. It is therefore also very clearly stated in the FAO manual on procedures for disease eradication by stamping out [2] that although often culling is the most cost-effective strategy, several social, economic, and other factors need to be evaluated before stamping out can be selected. These factors include “whether or not slaughter of infected animals is likely to gain community acceptance on religious, ethnic, animal welfare and other social and economic grounds” [2]. The fact that the impact of the stamping-out approach on livestock and companion animal owners goes far beyond financial loss is often overlooked [4]. In order to justify culling of animals as part of a control strategy, substantial evidence for its necessity is needed. Making evidence-based decisions requires, first and foremost, valid and justified research, which is essential to obtain the best available approximation to the truth [5] and requires that the outcome can be assessed objectively, that the data obtained can be generalized, and that the research can be reproduced. Strict categorization of test and outcome variables is essential to assess any effect. Thus to assess the effect of culling will require a study design in which animals are randomly allocated into cases and controls, whereas biased culling of haphazardly caught animals cannot be regarded as valid research. For valid research to be justified, it must be conducted in a way that respects and protects, and it must use relevant subjects who share risks and benefits without bias, as described in the International Ethical Guidelines for Biomedical Research Involving Human Subjects [6]. Since preventive measures for zoonotic diseases are made to safeguard humans rather than the animals, there is a strong argument for the justified research approach to evaluate them. Research assessing effectiveness of zoonotic disease control programmes must also adhere to these principles, and each measure should be assessed independently in a justified manner. Before introducing culling as a component in a control programme for zoonotic (or other) diseases, a risk analysis should be undertaken that considers the different options [7]. This should include a comprehensive assessment of the impact and acceptability of the proposed measures in the target communities. Application of universal standard recommendations is not a viable option, as cultural and religious beliefs differ throughout the world and call for local adaptations.

Eradication of transboundary animal diseases : can the rinderpest success story be repeated?

A matrix system was developed to aid in the evaluation of the technical amenability to eradication, through mass vaccination, of transboundary animal diseases (TADs). The system involved evaluation of three basic criteria - disease management efficiency, surveillance and epidemiological factors - each in turn comprised of a number of elements (17 in all). On that basis, 25 TADs that have occurred or do occur in southern Africa and for which vaccines are available, in addition to rinderpest (incorporated as a yardstick because it has been eradicated worldwide), were ranked. Cluster analysis was also applied using the same criteria to the 26 diseases, creating division into three groups. One cluster contained only diseases transmitted by arthropods (e.g. African horse sickness and Rift Valley fever) and considered difficult to eradicate because technologies for managing parasitic arthropods on a large scale are unavailable, while a second cluster contained diseases that have been widely considered to be eradicable [rinderpest, canine rabies, the Eurasian serotypes of foot and mouth disease virus (O, A, C & Asia 1) and peste des petits ruminants] as well classical swine fever, Newcastle disease and lumpy skin disease. The third cluster contained all the other TADs evaluated with the implication that these constitute TADs that would be more difficult to eradicate. However, it is acknowledged that the scores assigned in the course of this study may be biased. The point is that the system proposed offers an objective method for assessment of the technical eradicability of TADs; the rankings and groupings derived during this study are less important than the provision of a systematic approach for further development and evaluation.

A Preliminary Molecular Phylogeny of the Namib Desert Darkling Beetles (Tenebrionidae)

A systematic classification of Namib Desert darkling beetles (Coleoptera: Tenebrionidae) based on morphological characters is complicated as strong selection pressures exerted by desert conditions have led to a suite of convergent morphological characteristics. Here we present a first and preliminary insight into the relationships within the tribes Zophosini, Eurychorini and Adesmiini using molecular methods. We analysed partial sequences of the mitochondrial genes cytochrome oxidase II and cytochrome b of 16 individuals comprising 12 species. Minimum Evolution, Maximum Parsimony, Maximum Likelihood and Bayesian inference were applied for analysing sequence data. The genus Pimelia was used as outgroup and for calibrating divergence time estimates. Overall, results supported phylogenies constructed on morphological characters. The proposed monophyly of the artificially defined tribe Zophosini did receive sufficient support, Speciation events in Namibian darkling beetles likely occurred during periods of aridification about 35 Mya, 16 Mya and 5–10 Mya. Those periods could be related to geological events and climate change due to the glaciation of Antarctica and the development of the Benguela current.

The African swine fever epidemic in West Africa, 1996-2002

African swine fever (ASF) is a contagious, highly fatal, haemorrhagic viral disease that only affects members of the Suidae family. Currently, no vaccine or treatment exists, so the disease has potentially devastating consequences for the pig industries, availability of affordable protein livelihoods and trade. This study aimed to consolidate historical information generated by working towards the control and eradication of ASF in previously unaffected countries in West Africa during 1996-2002. This descriptive analysis entailed the evaluation and review of archived records and reports of outbreaks, data from veterinary services, veterinary consultants and peer-reviewed publications. Specifically, the analysis focused on establishing the sequence of events in the spread of the disease throughout the region, as well as the possible sources and pathways (mostly human-driven, i.e., movement of pigs and swill feeding). The socio-economic aspects of the epidemic were also assessed. Finally, the prevention and control measures applied were described and evaluated. Major challenges for control that were identified involved lack of capacity to respond to an outbreak of animal disease and the nature of the pig sector in the affected countries. Most of the pigs were produced in low biosecurity subsistence husbandry systems. Actions taken by producers to limit economic losses due to the epidemic (e.g., illegal selling of pigs and infected pork, hiding of outbreaks) increased the risk of spread and frustrated control efforts. The disease has persisted in an endemic state ever since and has negatively affected pig production and marketing in most of these countries. The analysis of this information will allow a better understanding of the disease dynamics in a region infected for the first time, and learning how the prevention and control interventions that were implemented worked or failed. This will help the development of better tailored, sustainable and locally sound interventions. The authors provide a set of recommendations for ASF prevention and control.

A questionnaire survey on diseases and problems affecting sheep and goats in communal farming regions of the Eastern Cape province, South Africa

A questionnaire of 15 questions was completed by four categories of respondents with the aim of establishing the experience and opinions of these groups on the constraints including animal health problems for communal, small-scale sheep and goat farming in the Eastern Cape province of South Africa. The questionnaires were completed independently and categories were representative of the areas investigated. Analysis of responses was done by means, ranges, votes and clusters of responses. Comparisons between the responses of the four categories were made to identify similarities or contrasts. The results revealed that of non-veterinary concerns, stock theft was the major problem for these farms. Nutrition was a further major constraint. A third area of significant concern was the provision or availability of facilities like fences, water troughs, dips and sheds. Lack of marketing and business skills were also seen as important deficiencies to be rectified so as to promote profitable farming. Of the most important veterinary problems identified, the provision, availability, cost and care of drugs and vaccines were seen as major stumbling blocks to effective disease control, as well as lack of access to veterinary services. The most important diseases that constrain small-ruminant livestock farming in the farming systems investigated were sheep scab and other ectoparasites, heart water, enterotoxaemia, internal parasites and bluetongue. A lack of knowledge in key areas of small-stock farming was revealed and should be rectified by an effective training and support programme to improve the contribution of small-ruminant farming to livelihoods in these communities.

Plant poisonings in livestock in Brazil and South Africa

Information on intoxication of livestock by plants in Brazil, in terms of cause, clinical signs and pathology, is compared with information on livestock poisoning by plants in South Africa. Plant poisoning, including mycotoxicosis, is considered to be one of three major causes of death in livestock in Brazil, which is one of the top beef producing countries in the world, with a cattle population of more than 200 million. Cattle production in South Africa is on a more modest scale, but with some 600 species of plants and fungi known to cause toxicity in livestock, as opposed to some 130 species in Brazil, the risk to livestock in South Africa appears to be much greater. The comparisons discussed in this communication are largely restricted to ruminants.