Twenty goats which served as the experimental group were administered ascorbic acid (AA) per os at a dosage rate of 100 mg/kg body mass, while 20 others served as controls and were given 10 mt each of sterile water. Forty minutes after the administration and loading, the goats were transported for 12 h. Handling and loading of the experimental and control groups of goats decreased (P < 0.05) the potassium and sodium serum concentrations. The concentration of serum chloride, sodium and calcium increased significantly (P< 0.05) immediately post-transportation, while potassium and magnesium decreased (P < 0.05) in the control goats. In AA-treated goats sodium and magnesium concentrations decreased abruptly (P< 0.05), while calcium increased significantly (P< 0.05) after transportation. Handling, loading and transportation adversely affected the electrolyte balance of the goats which suggested respiratory alkalosis, dehydration and muscular damage in the transported goats, and the administration of AA alleviated the adverse effects of road transportation stress on serum electrolytes.

The present study was performed in order to evaluate the effects of lower than usual industry levels of dietary trace minerals on plasma levels, faecal excretion, performance, mortality and morbidity in growing-finishing pigs in a hot African climate. Group 1 (n =100 pigs) received a diet with common industry levels of trace minerals. Group 2 (n =100 pigs) received reduced dietary trace mineral levels but were fed the same basic diet as Group 1. Mortality, morbidity, pig performance and carcass measurements were evaluated. Two pigs in Group 1 and three pigs in Group 2 died. Thirteen pigs in Group 1 and 27 pigs in Group 2 were medically treated (P < 0.05). Carcass masses, back fat depth, loin depth, and lean percent were not significantly different between the groups. However, the carcasses when evaluated revealed a non-significant higher back fat thickness, lower loin eye area and percentage of fat free lean in barrows compared to gilts within each group. Despite lower initial masses, pigs fed diets containing industry levels of trace minerals were heavier (P < 0.05) and had a higher (P < 0.05) than average daily gains compared to those that received a diet containing lower levels of trace minerals. Faecal zinc excretion was significantly lower (P < 0.05) in pigs fed with lower dietary zinc levels. Copper, manganese and iron excretion were not affected (P > 0.05) by the dietary levels of these trace minerals. Plasma trace mineral concentrations were not affected by the dietary treatment.

Finding appropriate ways of dealing with the problem of tsetse and trypanosomosis will be an important component of efforts to alleviate poverty in Africa. This article reviews the history of economic analyses of the problem, starting with the use of cost to guide choice of technique for tsetse control in the 1950s, followed by work in the 1970s and 1980s linking these to the impact of the disease on livestock productivity, and in the 1990s to its wider impact. In the current situation, with limited resources and a range of techniques for controlling or eliminating tsetse, the cost implications of choosing one technique or another are important and a recent study reviewed these costs. A novel approach to assessing the potential benefits from removing trypanosomosis by creating 'money maps' showed that high losses from animal trypanosomosis currently occur in areas with high cattle population densities on the margins of the tsetse distribution and where animal traction is an important component of farming systems. Given the importance of the decisions to be made in the next decade, when prioritising and choosing techniques for dealing with tsetse and trypanosomosis, more work needs to be done underpinning such mapping exercises and estimating the true cost and likely impact of planned interventions.

Tsetse-fly and the disease it transmits, trypanosomosis, remain an enormous disease challenge in the 37 countries of sub-Saharan Africa where the impact continues to be manifest in disease burden, increased level of poverty and decreased agricultural productivity. The impact also extends over an estimated 10 million km² (a third of the African continent) of land area, a third of which contains some well-watered part of the continent, thus denying humans and livestock of potentially rich arable and pastureland. The disease is a threat to an estimated 50 million people and 48 million cattle with estimated annual losses in cattle production alone of 1-1.2 billion US$. These losses are due to stock mortality and depressed productivity, which may be of meat, milk, reproduction or traction. Beyond its direct effects on humans and livestock is its impact on African agriculture and the livelihood of the rural population in the affected countries: the fly and the disease influence where people decide to live, how they manage their livestock, and the intensity and the mix of crop agriculture. The combined effects result in changes in land use and environment which may, in turn, affect human welfare and increase the vulnerability of agricultural activity. Trypanosomosis is, therefore, both a public health and an agricultural development constraint. The challenges that the elimination or control of tsetse fly and trypanosomosis pose as well as the opportunities to develop appropriate intervention technologies are discussed in this presentation.

The use of new, highly sensitive diagnostic methods has revealed persistent infections to be a common feature of different tick-borne diseases, such as babesiosis, anaplasmosis and heartwater. Antigenic variation can contribute to disease persistence through the continual elaboration of new surface structures, and we know in several instances how this is achieved. Known or suspected mechanisms of persistence in babesial parasites include cytoadhesion and rapid variation of the adhesive ligand in Babesia bovis and genetic diversity in several merozoite stage proteins of different Babesia spp. In Anaplasma, extensive variation in the pfam01617 gene family accompanies cycling of organism levels in chronic infection. One result from the pioneering research at Onderstepoort is the definition of a related polymorphic gene family that is likely involved in immunity against heartwater disease. We are beginning to understand the sizes of the antigenic repertoires and full definition is close, with the possibility of applying simultaneous high-throughput sequencing to the order of 1 000 small genomes. We also, for the first time, can consider modifying these genomes and looking at effects on persistence and virulence. However, important biological questions remain unanswered; for example, why we are seeing a new emerging Anaplasma infection of humans and is infection of endothelial cells by Anaplasma significant to persistence in vivo.

Sir Arnold Theiler's research in 1908/09 led to the discovery of the first rickettsial pathogen, Anaplasma marginale, and set the stage for his development and implementation of an effective live vaccine based on a less virulent strain, A. marginale ss. centrale. His 1910 report, describing A. marginale, is among the classic monographs in infectious disease research, presenting not only observations in exacting detail but also highlighting the deductive reasoning leading to association of a new pathogen with a specific disease. With a centennial perspective and both conceptual frameworks and molecular tools unimaginable in Theiler's time, the significance of several observations in the original report- cyclic bacteremia, strain superinfection, and taxonomic position-is now clear and highlight the broad applicability of key principles of pathogen biology.

Heartwater is an economically serious tick-borne disease of ruminants caused by the intracellular bacterium Ehrlichia ruminantium. The disease has traditionally been controlled by four different approaches: controlling the tick vector by dipping, establishing endemic stability, performing immunisation by infection and treatment, and preventing the disease by regular administration of prophylactic antibiotics. The first three of these methods are subject to failure for various epidemiological reasons, and serious disease outbreaks can occur. Prophylaxis is effective, but very expensive, and the logistics are daunting when large herds of animals are involved. The development of a safe, cheap and effective vaccine is the only likely way in which heartwater can be economically controlled, and over the past 15 years three new types of experimental vaccine have been developed: inactivated, attenuated, and recombinant vaccines. These new vaccines have shown varying degrees of promise, but none is as yet sufficiently successful to be marketable. We describe the experimental products, and the various technical and biological difficulties which are being encountered, and report on ways in which new technologies are being used to improve vaccine effectiveness.

Research on this economically important disease of ruminants, especially sheep, which had been named bluetongue by farmers in the 19th century, has been part and parcel of the activities at Onderstepoort ever since its establishment in 1908 and therefore covers a full century of the OVI's existence. In view of Onderstepoort's centenary celebration a brief overview of this research is given in terms of the historic milestones which influenced and guided global research on this and other viral diseases of animals.

Veterinary education commenced in South Africa in 1920 at the Onderstepoort Veterinary Institute in South Africa in association with the Transvaal University College, now the University of Pretoria. Sir Arnold Theiler, Director of Veterinary Research and Education, was the first Dean. Today there are 46 veterinary training institutions in Africa of which 21 are in sub-Saharan Africa. Veterinary services are indispensable to the sustained health and wellbeing of animals and humans, and agricultural economies of countries worldwide. Veterinary education, postgraduate training, and research, and adequate numbers of veterinarians, are essential to satisfy the millennium development goals, the objectives of NEPAD and the African Union, and the agreements regulating international trade. The relevance of the veterinary profession internationally is currently subject to profound scrutiny. Its contributions are assessed against major environmental, demographic, political, disease, technological and economic needs. The scope of veterinary training in future will have to emphasise veterinary public health, food safety, emerging diseases, international trade, bioterrorism, and biomedical research, within the context of a one-health system focusing on the interface between wildlife, domesticated animals, humans, and their environment. Within the context of time available, it would mean reducing the time allocated to training in the field of companion animals. A brief history and scope of veterinary education; current international trends in veterinary education and provisioning; and some perspectives on future veterinary training and initiatives applicable to Africa are provided.

Prevention, eradication and control of animal diseases, as well as public health assurance are major functions of veterinary authorities. The strategies to control animal diseases differ from disease to disease but are often similar on a disease basis from country to country depending on the main objective of the measure employed. These measures include among others movement control and quarantine, vaccination, treatment and mass slaughtering. However, not every country uses all these control measures at the same time. A combination of measures may be employed to avoid spreading of the disease from infected to clean animals and success is dependent on a variety of factors, including the strength and capacity of the veterinary services, cross border efforts for disease surveillance, political will, diagnostic facilities and financial support.