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.