Experience in control of avian influenza in Africa.

The first outbreak of H5N1 highly pathogenic avian influenza (HPAI) in Africa was confirmed at Kaduna, Nigeria, on 8 February 2006. Within three months, seven other countries on the continent, Burkina Faso, Cameroon, Côte d'Ivoire, Djibouti, Egypt, Niger and Sudan, were infected. More recently Ghana and Togo became infected. The origin of the introduction of the disease to Nigeria and the other infected countries is still unknown, owing to lack of adequate tracing of the movements of poultry and poultry products and lack of reliable epidemiological data from the affected countries. The preventive measures adopted in countries free from H5N1 HPAI include selective or total bans on the importation of poultry and poultry products from infected countries. All the infected countries have implemented more or less the same internationally recommended disease control measures including quarantine, stamping-out and active surveillance, while poultry vaccination was carried out in Côte d'Ivoire and Egypt. These control measures, adopted and implemented by weak veterinary services, cannot explain the apparent 'epidemiological silence' of H5N1 HPAI in Africa, and further studies are needed to explain the different behaviour of the H5N1 HPAI virus in Africa and Asia.

Xerovac: an ultra rapid method for the dehydration and preservation of live attenuated Rinderpest and Peste des Petits ruminants vaccines.

The accepted procedure for the long-term preservation of live viruses and bacteria in vaccines has been lyophilisation. We show that thermolabile viruses can be dehydrated in vitro, within 18 h, in an excipient containing trehalose. We further demonstrate that in the resulting dehydrated state, where the viruses are captive in a metastable glass composed of trehalose, they are capable of resisting 45 degrees C for a period of 14 days with minimal loss of potency. The degree of thermotolerance achieved matches that of current 'thermostable' lyophilised vaccines, but with the distinct advantage of a shorter, cheaper and simpler process. The development and utilisation of this process can make significant improvements in current live virus vaccine production. It presents a further step away from dependence on mandatory low temperature refrigerated storage and could lead to greater confidence in vaccine stability, potency and efficacy.

[Epidemiology of bovine brucellosis in Mali: serologic investigation and initial isolation of strains of Brucella abortus]. / Epidémiologie de la brucellose bovine au Mali: enquête sérologique et isolement des premières souches de Brucella abortus.

The authors report the results of an epidemiological survey of bovine brucellosis in Mali, based on a relatively representative sample of 1,000 serum samples from 236 herds. The prevalence of infection in the herds, established by indirect enzyme-linked immunosorbent assay (ELISA) was 53% +/- 6.4. The proportion of animals infected was 23.3% +/- 2.5, falling to 22% when compared with the basic serum pool of 9,466 samples. This rate was relatively high in stationary herds in the semi-arid, sub-humid and arid zones. Four strains of Brucella abortus were isolated from cattle bearing hygromas.