[Avian influenza viruses--new causative agents of human infections].

Introduction: Influenza A viruses can infect humans, some mammals and especially birds. Subtypes of human influenza A viruses: A(H1N1), A(H2N2) and A(H3N2) have caused pandemics. Avian influenza viruses vary owing to their 15 hemagglutinins (H) and 9 neuraminidases (N).
Human Cases of Avian Influenza a: In the Netherlands in 2003, there were 83 human cases of influenza A (H7N7). In 1997, 18 cases of H5N1 influenza A, of whom 6 died, were found among residents of Hong Kong. In 2004, 34 human cases (23 deaths) were reported in Viet Nam and Thailand. H5N1 virus-infected patients presented with fever and respiratory symptoms. Complications included respiratory distress syndrome, renal failure, liver dysfunction and hematologic disorders. Since 1999, 7 cases of human influenza H9N2 infection have been identified in China and Hong Kong.
The Importance of Human Infection With Avian Influenza Viruses: H5N1 virus can directly infect humans. Genetic reassortment of human and avian influenza viruses may occur in humans co-infected with current human A(H1N1) or A(H3N2) subtypes and avian influenza viruses. The result would be a new influenza virus with pandemic potential. All genes of H5N1 viruses isolated from humans are of avian origin.
Prevention and Control: The reassortant virus containing H and N from avian and the remaining proteins from human influenza viruses will probably be used as a vaccine strain. The most important control measures are rapid destruction of all infected or exposed birds and rigorous disinfection of farms. Individuals exposed to suspected animals should receive prophylactic treatment with antivirals and annual vaccination.