Tanah Karo, Indonesia ? Local tests show bird flu has killed a fifth member of an Indonesian family, a senior medical official said.

In all, eight members of the family in Tanah Karo village on Sumatra are suspected of having contracted the virulent H5N1 bird flu virus. The other four died from the disease early last week, said Nyoman Kandun, head of the Health Ministry’s office of communicable disease control.

Indonesia’s official human death toll from the virus is now 25, the world’s second-highest after Vietnam, which recorded about four dozen deaths. International health experts said earlier this year that outbreaks of H5N1 infections in people and poultry had been largely stamped out in Vietnam.

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, and experts study “cluster” cases looking for signs that H5N1 may have mutated into a form easily passed between humans – a scenario that many fear could trigger a global human pandemic.