According to local tests, a fifth member of an Indonesian family has died of bird flu. The other four died from the disease early last week. In all, eight members of the family in Tanah Karo village on Sumatra are suspected of having contracted the virulent H5N1 bird flu virus.
Officials pay particular attention to cases of multiple related deaths such as those in Indonesia. The virus now is almost always transmitted from birds to humans.

The experts say they are continuing to investigate the case of bird flu and are trying to find the source of the virus. Investigators were checking poultry near the family's village, since veterinarians had found no signs of bird flu among chickens and other animals in the village itself.

International experts hope Vietnam's campaign to vaccinate its poultry against H5N1 will serve as an example for other countries in dealing with the virus, which has killed more than 100 people in all.

Once the epicenter for bird flu, Vietnam hasn't had seen any people infected since November and there haven't been any poultry outbreaks since December. Vietnam started its nationwide eradication campaign in August 2005. Officials in the poor communist nation say they vaccinated millions of chickens and ducks, slaughtered millions more and educated citizens about the disease.

Outside experts, however, caution that immunization is not a simple solution.