A WHO-recognised laboratory confirmed four bird flu cases in Indonesia on Saturday, including a 10-year-old girl who died this week in Bandung city and a shuttlecock maker who is alive, a government official said.
"The girl is confirmed by the WHO," said I Nyoman Kandun, director-general of communicable disease control. He added that the source of the girl's infection was likely to be sick poultry in her village in Bandung in west Java.
The laboratory in Hong Kong, whose findings are considered definitive by the global medical community, also confirmed H5N1 infection in the 18-year-old shuttlecock maker, who used to sort feathers in a factory in Surabaya in east Java.
He is alive in hospital. His condition was not known. The third person is a 43-year-old in Jakarta who is alive, and the fourth is a 39-year-old, also from the capital, who died, although it was not immediately clear when.
Confirmation of the source of the two deaths brings the H5N1 death toll in Indonesia to 35, and the world-wide total to 126. The girl's 18-year-old brother, who also died on Tuesday, tested positive locally for H5N1 this week, but was not considered a bird flu case by the Hong Kong laboratory.
"It's a borderline case ... It may be because of the procedure of specimen collection, handling, maybe the Hong Kong lab had problems. We had the same experience before in another case," Kandun told Reuters.
Though the brother is not classified as a H5N1 case, Kandun said he exhibited the same clinical symptoms as his sister.
Dead chickens were found in their village a few days before they fell ill and sick poultry may well have been the source of their infection, he said.
Kandun considered the case of the siblings as Indonesia's seventh human bird flu cluster since the disease found its way into chickens in the sprawling archipelago in late 2003.
Indonesia's bird flu problem captured the world's attention this month after the virus killed as many as eight members of a family in a remote village in Sumatra, one of Indonesia's largest islands in the far west.
Health experts and epidemiologists have narrowed the likely source of their infection to poultry but they say limited human-to-human transmission may also have occurred.
But the WHO says genetic analyses of virus samples from the Sumatran victims have not shown changes or traits that are known to date to allow the virus to spread efficiently among people - a necessary precursor to the start of a pandemic.
Some who died later had taken care of those who fell sick earlier and may have been infected during close and prolonged contact.
Kandun said victims in every one of the seven clusters were blood relatives - which gives credence to a theory that people who are infected by the H5N1 are genetically predisposed to it due to a unique make-up of their respiratory tracts. "Maybe they have genetic susceptibility," he said.
Another observation that backs up the theory is that spouses were never infected even though they had close contact with the Sumatran victims. "If you look at two wives in the family, they were very close to the sick members and they are not sick," Kandun said.