In 1997, 18 people were infected in Hong Kong with an avian influenza A(H5N1) virus from chicken. This type of interspecies transmission was never detected before and could have resulted in the development of a pandemic strain. The occurrence suggests that the pig is not needed for the emergence of pandemic influenza virus strains. Characteristics of the strains involved are discussed in relation to the question why, on the one hand, these strains were able to infect humans but on the other hand were not able to start an epidemic.

Avian influenza virus, Interspecies transmission, Pandemic influenza,
Department of Virology

Osterhaus, A.D.M.E, de Jong, J.C, Rimmelzwaan, G.F, & Claas, E.C.J. (2002). H5N1 influenza in Hong Kong: Virus characterizations. Vaccine, 20(SUPPL. 2). doi:10.1016/S0264-410X(02)00138-X