Sorasak Lochindarat, MD.

Avian Influenza A (H5N1) Infection in Humans
The Writing Committee of the World Health Organization (WHO) Consultation on Human Influenza A/H5

  An unprecedented epizootic avian influenza a (h5n1) virusthat is highly pathogenic has crossed the species barrier in Asia to cause many human fatalities and poses an increasing pandemic threat. This summary describes the features of human infection with influenza A (H5N1) and reviews recommendations for prevention and clinical management presented in part at the recent World Health Organization (WHO) Meeting on Case Management and Research on Human Influenza A/H5, which was held in Hanoi, May 10 through 12, 2005. 1Becausemany critical questions remain, modifications of these recommendations are likely.

incidence

       The occurrence of human influenza A (H5N1) in Southeast Asia (Table 1) has paralleled large outbreaks of avian influenza A (H5N1), although the avian epidemics in 2004 and 2005 have only rarely led to disease in humans. The largest number of cases has occurred in Vietnam, particularly during the third, ongoing wave, and the first human death was recently reported in Indonesia. The frequencies of human infection have not been determined, and seroprevalence studies are urgently needed. The expanding geographic distribution of avian influenza A (H5N1) infections, with recent outbreaks in Kazakstan, Mongolia, and Russia, indicates that more human populations are at risk. 2,3