In 1908 a Pan-African Veterinary Conference formed part of the inauguration ceremony of the Onderstepoort Veterinary Laboratory. Attended by 18 delegates from 12 countries in southern Africa, including the four colonies and three protectorates forming British South Africa, Rhodesia, German South West Africa, Portuguese East Africa, Madagascar and the Belgian Congo, discussions focussed on the animal diseases of the region with the emphasis on trypanosomosis (nagana) and East Coast fever. The successful meeting was followed by a series of similar conferences held in different African countries during the first half of the 20th Century.

The occurrence of genetic exchange is not only a fundamental property of an organism but its occurrence provides us with methods of analysis that can be used to dissect the basis of important traits. This paper will review the current evidence for a sexual cycle in Trypanosoma brucei and illustrate how genetic analysis can be used as a tool to identify genes of relevance to the disease, its treatment and transmission. The role of this process in the generation of diversity in the field will be illustrated by considering populations of the three sub-species of T. brucei and how the availability of genome sequence data has been exploited to study whether genetic exchange occurs in the trypanosomes infecting livestock. Finally, the use of population genetics as a methodology to identify genes under selection will be discussed and this will be illustrated as an approach to validating markers for drug resistance with examples from other parasitic protozoa.

Rinderpest is one of the few diseases which have changed the course of world history. Originally an Asian disease, for centuries it had a devastating impact in Europe when introduced by returning and marauding armies accompanied by cattle as well as by cattle trade. Nowhere was its impact more dramatically expressed than in Africa where the sequel to its introduction into the Horn of Africa was a devastating panzootic throughout sub-Saharan Africa during the last decade of the 19th century extending into the 20th century. Massive deaths of livestock, wild animals and the people dependent on them led to widespread human misery and changed the face of the African continent forever.

The declining efficacy of acaricide treatment as a means of reducing the prevalence of Theileria parva infections in sub-Saharan Africa has intensified efforts to achieve control through immunization of susceptible cattle. The infection and treatment method of immunization has enjoyed a resurgence with the availability of more effective cold chain facilities, although concerns remain regarding the possibility of vaccine strains spreading in local tick populations. In addition, an in-depth understanding of protective mechanisms deployed by immune cattle and the antigens targeted by them has led to substantial progress in the development of candidate subunit vaccines against both sporozoite and schizont stages of the parasite. The likely success of these vaccines, as well as infection and treatment immunization, will ultimately depend on the extent to which they disturb the endemic status of the parasite. These issues are discussed in the light of recent information on the genotypic diversity of T. parva in the field and the extent to which this is compromised by the immune response.

As we join Onderstepoort in celebrating its centenary, it is worth reflecting that tick-borne infections of wildlife and livestock have been part of everyday life in Africa for many, many generations. While much has changed since Watkins-Pitchford started developing short-interval dipping trials with arsenicals to contain the new epidemic of East Coast fever in southern Africa 100 years ago, when it comes to the impacts of tick-borne infections, many of the same challenges remain.

African horsesickness (AHS) played a major role in the history and development of southern Africa, both in times of peace and of war. Frequent epidemics of AHS resulted in major transportation impediments.The viral (filterable) nature of the aetiological agent was proven in 1900 by Sir John M'Fadyean in London, making it one of the first animal diseases for which this had been demonstrated. Similarly, the cultivation of AHS virus in the brain of mice and its subsequent attenuation were also amongst the first such feats for animal viruses. Interestingly, both milestones followed the initial work of Max Theiler (son of Sir Arnold) with yellow fever virus.

Edwardsiella tarda was recovered from cultured freshwater catfish (Claries gariepinus) with a prevalence rate of 0.42% in summer season. Experimental infectivity studies of E. tarda in Catfish and Tilapia nilotica were done using the intraperitoneal (I/P) and intramuscular (I/M) routes. Experimentally infected Catfish with a dose of 0.3 ml from E. tarda bacterial suspension of 108 CFU/ml manifested pathognomonic clinical signs and postmortem lesions than the experimentally infected Tilapia nilotica. Application of PCR technique for rapid detection of E. tarda infection in the experimentally infected fishes gave positive reaction in 4th day post infection in catfish and the 7th day post infection in Tilapia nilotica.

Private practice became the major vocation of local veterinarians from about 1945. Soga was probably the first qualified South African veterinarian to practice privately on a limited scale in the 1800s. Jack Boswell was the first locally qualified (in 1934) veterinarian to go directly into practice without first working for the government and is regarded as the father of private practice in South Africa. Boet Bekker worked for the government before setting up a successful practice in 1935.

Due to logistical problems in obtaining sufficient blood samples from apparently healthy animals in the wild in order to establish normal haematological reference values, only limited information regarding the blood platelet count and morphology of free-living lions (Panthera leo) is available. This study provides information on platelet counts and describes their morphology with particular reference to size in two normal, healthy and free-ranging lion populations. Blood samples were collected from a total of 16 lions. Platelet counts, determined manually, ranged between 218 and 358 x 109/ℓ. Light microscopy showed mostly activated platelets of various sizes with prominent granules. At the ultrastructural level the platelets revealed typical mammalian platelet morphology. However, morphometricanalysis revealed a significant difference (P < 0.001) in platelet size between the two groups of animals. Basic haematological information obtained in this study may be helpful in future comparative studies between animals of the same species as well as in other felids.

The present study was designed to assess and compare three different formulations of the new Onderstepoort infectious coryza (IC) quadrivalent vaccine, which contain an NAD-independent strain of Avibacterium paragallinarum (previously known as Haemophilus paragallinarum), and a commercial IC vaccine, not containing an NAD-independent strain, for their safety and ability to protect chickens of varying ages against virulent challenges with four different serovars of A. paragallinarum, including the NAD-independent strain of the C-3 serovar. Four groups of 140 chickens each were vaccinated at the age of 17 weeks and revaccinated at the age of 19 weeks with each of the four vaccine formulations. A similar sized group of non-vaccinated chickens was used as control. Two rounds of challenge were conducted: a group of chicken in each vaccination group was challenged between 31 and 35 weeks of age, while another group was challenged between 51 and 55 weeks of age. The ''in-contact'' challenge model was used in this experiment. For each vaccination group, the four challenge strains representing four local serovars were used in each challenge round. The efficacy of the vaccines was compared based on overall protection levels obtained and the duration of protection. The safety of the different vaccines was determined by the severity of post-vaccination reactions. The need for the incorporation of the NAD-independent strain in the vaccine was evidenced by the low protection level against NAD-independent challenge recorded in the group of birds vaccinated with the commercial vaccine. The results obtained confirmed not only the variation in virulence of different South African serovars, with serovar C-3 being the most virulent and serovar B having almost no virulence but also the age related increase in susceptibility. The importance of a suitable formulation of the vaccine is discussed.