Avian influenza – cumulative number of cases – update 18

19 May 2005

WHO is updating its table showing cumulative numbers of human cases of H5N1 avian influenza broken down according to phases in the outbreak, which began in December 2003. [Cumulative Number of Confirmed Human Cases of Avian Influenza A/(H5N1) Reported to WHO]. Numbers for Viet Nam, where the vast majority of recent cases have occurred, have been amended in line with case counts provided by the Ministry of Health during late April and May. Since the third wave of infection began in Viet Nam in mid-December 2004, 49 cases have been reported. Of these cases, 17 were fatal. The most recent case was reported to the ministry on 17 April.

WHO has asked the Ministry of Health in Viet Nam to supplement the numbers with data on individual cases. Rapid field investigation of new cases, especially when these occur in clusters, remains essential to assess possible changes in transmission patterns that could indicate improved pandemic potential of the virus.

Since January 2004, when human cases of H5N1 avian influenza were first reported in the current outbreak, 97 cases and 53 deaths have been reported in Viet Nam, Thailand and Cambodia. Viet Nam, with 76 cases and 37 deaths, has been the most severely affected country, followed by Thailand, with 17 cases and 12 deaths, and Cambodia, with 4 cases and 4 deaths.