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Monovalent, inactivated and adjuvanted vaccines against African horse sickness, prepared with serotypes 5 and 9, were tested on guinea-pigs to select the formulation that offered the greatest immunity. The final formulation of the vaccines took into account the immune response in the guinea-pig and the inflammatory properties of two types of adjuvant previously tested on target animals. A pilot study was subsequently conducted on horses using a vaccine prepared with serotype 9. The vaccine stimulated neutralising antibodies from the first administration and, after the booster dose, 28 days later; high antibody levels were recorded for at least 10 months. The guinea-pig appears to be a useful laboratory model for the evaluation of the antigenic properties of African horse sickness vaccines.

African horse sickness is a vector-transmitted viral disease that affects equidae. The authors report cases of disease that occurred in Namibia between 2006 and 2008. These were recorded by staff of the Istituto Zooprofilattico Sperimentale dell'Abruzzo e del Molise 'G. Caporale' and the Central Veterinary Laboratory in Windhoek. All cases described were confirmed by laboratory testing. This study received the support of Namibian state and private veterinarians and horse breeders.

The shelf-life of a culture medium is the maximum period of validity for optimum preparation and preservation. Apart from the composition of the medium, the factors that influence shelf-life are sterilisation method, preservation and packaging procedures, storage temperature and exposure to light. The shelf-life of a culture medium is defined by evaluating its basic chemico-physical characteristics so as to obtain the correct growth and characterisation of a specific microorganism. This research was conducted from March to September 2003 on 12 'critical' culture media, i.e. media that had a coded shelf-life of not more than thirty days. Each medium was produced in three separate batches, with a total of 5 940 samples. The purpose of the study was to define a longer period of validity than that coded for each medium by evaluating weight reduction, pH, fertility and sterility. The shelf-life observed for each medium was longer than those coded. The new shelf-life takes into account both the operational needs of complex organisational structures and the efficiency of the medium, depending on its chemico-physical characteristics and storage and preservation methods.

Aims: The prevalence, level of contamination and epidemiological profile of Listeria monocytogenes were investigated in two meat-producing plants during a 20-month period., Methods and Results: Sampling for L. monocytogenes was carried out in a cattle slaughterhouse (n = 72) and a swine meat-processing plant (n = 68) during a 20-month period. Swabs and food samples were analysed with the most probable number (MPN) technique for L. monocytogenes and the isolated strains were characterized by AscI-restriction analysis pulsed-field gel electrophoresis (REA-PFGE). Contamination of meat and meat products was always at low level (below 50 MPN per gram). The seven L. monocytogenes positive samples isolated in the bovine slaughterhouse yielded strains with the same REA-PFGE profile. However, the seven strains isolated in the swine meat processing plant showed six different profiles. Two of them showed indistinguishable profiles with L. monocytogenes strains collected from other meat processing facilities located in the same area., Significance and Impact of the Study: The genotyping method is a valuable tool to investigate contamination sources. The study of REA-PFGE profiles indicated that environmental contamination was probably responsible for the persistence of over 16 months of one strain of L. monocytogenes in the cattle slaughterhouse. Several meat suppliers could be responsible for the contamination in the pig meat processing facility, and this is confirmed by the finding of some identical strain in other meat processing facilities located in the same area.