Low Pathogenicity Avian Influenza H9N2 Virus in Africa
Low Pathogenicity Avian Influenza H9N2 Virus in Africa
Abdel Satar Arafa
ABSTRACT
Abstract | Avian influenza virus (AIV) of the subtype H9N2 virus has been detected worldwide in wild and domestic birds as well as in few occasions in mammals. The virus was recorded in several African countries, with endemic status in Egypt and frequently reported in different other countries like Morocco, Tunisia, Uganda, Benin and Togo since 2016. Egypt and Morocco have applied a mass vaccination programme for commercial poultry to control the infection. The isolated viruses from poultry in Africa have been classified as G1 ‘Western’ Viruses and related to the circulating viruses in the Middle East. In addition to Y439 lineage recorded in South Africa farmed ostriches. The infection with H9N2 is frequently displaying moderate-to-high morbidity and mortality in the field especially when comes associated with bacterial or viral infections or with many other factors such as poor biosecurity, mal-nutrition and managemental problems. LPAIVs H9N2 in chickens tend to show more respiratory tropism with some strains also show gastrointestinal tropism. The ideal mechanism of transmission among birds varies by host species and virus strain. The respiratory and contact transmission are likely the primary routes of transmission and may partly arise initially as an adaptation to poultry which clearly has implication for zoonotic transmission. Inactivated vaccines are the most common vaccines used to control H9N2 viruses, however they have a wide antigenic variability in different lineages.
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July 2022
Vol. 10, Iss. 2
