Risk Factors, Threats And Prevention Of Highly Pathogenic Avian Influenza (HPAI) In African Countries

Abstract

Highly pathogenic avian influenza (HPAI) is a viral disease that affects the digestive, nervous and respiratory systems of all domestic and wild birds with high morbidity and mortality. It is highly contagious disease which can be fatal in humans. The avian influenza viruses (AIVs) are classified as types A, B and C with 15 subtypes of the type A. To date, all disease causing HPAI Viruses belong to H5 or H7 subtypes; and affect pigs and humans with the pigs serving as a mixing vehicle for re-assortment of the virus. The domestic ducks get infected without showing clinical signs and serve as a source of infection for domestic poultry. Outbreaks of HPAl in Europe, Asia and Turkey are reported to be associated, with the presence of wet lands and lakes where migratory birds rest. In some African countries like Nigeria, such wet lands exist with free flying wild birds and domestic ducks visiting and resting. The possible source of introduction into a country could be through importation or smuggling of infected poultry products across the borders and through migratory birds that fly through identified pathways. The status of HPAl in many African countries including Nigeria is still under investigation so that appropriate strategies / measures to prevent introduction of the disease into the country can be implemented and / or strengthened through restriction of importation of poultry and poultry products from high risk countries, effective disease surveillance, functional National Veterinary services, quarantine and community based participatory epidemiological system for HPAI surveillance and control. This article reviewed the global epidemiology and risk factors of HPAI infection in Nigeria and other African countries with emphasis on specific preventive measures that can reduce introduction of the virus into the country and the epidemiological surveillance for case detection / identification, screening and management. This review provides useful information and updates for health workers in tropical countries on the trends of AIVs and HPAI, diagnostic criteria using case definitions for both community and health facility levels and management protocols for confirmed cases as recommended by the World health Organization.

African Journal of Clinical and Experimental Microbiology Vol. 10 (2) 2009: pp.99-116