Head of the bird flu ward at Bandung's Hasan Sadikin hospital, Hadi Yusuf said the surviving brother's prognosis was not good. The brothers were known to bring chickens to feed their dog, but their sister had no known contact with infected poultry, leading scientists to investigate this as a cluster case.
"If it is true that the youngest did not touch chickens at all and she had bird flu, we need to suspect she got it from the brothers," Yusuf said. The girl's test results should be back from the laboratory on Wednesday.
Currently, the bird flu virus has only killed people who have been in close contact with poultry, but cluster cases are considered particularly dangerous because they are one of the first steps toward the virus mutating into a strain easily transmittable between humans.
A cluster case was discovered in Indonesia's Northern Sumatra province more than four months ago, and took the lives of seven members of a family. A mutation occurred in this case, but World Health Organization scientists said it only came about through prolonged contact between family members -- parents caring for a sick child, for example -- and said the change was insignificant.
Containing the spread of the disease is also imperative to prevention of a human-to-human mutation, and Indonesia has come under fire from world health experts for doing too little to control their infections. Currently the country has the highest bird-flu-related death toll with 51 of the 146 WHO-confirmed bird flu deaths.
David Nabarro, bird flu coordinator for the United Nations, said Indonesia was making progress in containing the disease, but that he was disappointed in the small amount of funds being pledged to the country by international donors.
"This unnerving discovery shows that the bird flu virus is still mutating, using human populations as breeding grounds for adaptive strains that could spread among people," said Mike Adams, author of "How to Beat the Bird Flu," "The continued mingling of humans with infected animals is a recipe for disaster, and the eventual emergence of a strain that's highly infectious to humans seems inevitable."