Avian influenza A(H5N1) - update 19: Investigation of possible human-to-human transmission in Viet Nam: new data are reassuring

6 February 2004

Investigation of possible human-to-human transmission in Viet Nam: new data are reassuring

NB: Please see correction in update 20

WHO has today received the results from studies of two viruses taken from members of a family cluster of H5N1 infection in Viet Nam. The family cluster has been under investigationas the first possible instance of limited human-to-human transmission of the H5N1 avian influenza strain. Virus genetic materials from two fatal cases in this cluster – sisters aged 23 and 30 years – have now been fully sequenced by the Government Virus Unit of Hong Kong’s Department of Health. Both viruses are of avian origin and contain no human influenza genes.

This finding, which indicates that the virus has not changed to a form easily transmitted from one person to another, is consistent with earlier findings from epidemiological investigations. No illness has been reported in other family members, in the local community, or in health workers involved in care of these patients.

China (poultry)

Chinese authorities have today confirmed H5N1 infection in poultry in an additional province. The H5N1 strain was detected in samples from infected chickens at two farms in the southern province of Jiangxi.

Altogether, H5N1 infection in poultry is confirmed or suspected at farms in 13 of China’s 31 provinces, autonomous regions, and municipalities.

No cases of human H5N1 infection have been reported in China to date.