Journal Watch

Abstract

Three types of influenza viruses have been identified: Types A, B and C. Only A and B cause human disease, and only type A causes pandemics. Influenza A viruses are characterised by two surface antigens, haemagglutinin (H) and neuraminidase (N), of which there are sixteen H subtypes and nine N subtypes. Only viruses of the H5 and H7 subtypes are known to cause the highly pathogenic form of influenza.