Jakarta (AsiaNews/Agencies) – Indonesia's 52nd death from bird flu has heightened fears about feared human-to-human transmission of the H5N1 virus. The health authorities today reported the death of a 20-year-old Indonesian man from Bandung city in West Java, where many other cases have occurred.

The boy died of respiratory problems but doctors had already ascertained he was suffering from bird flu. His 25-year-old brother died a few days earlier on 24 September, with symptoms of the same disease. His death came about before blood samples could be taken for testing and he has been included on the list of suspect cases.

Senior Health Ministry official, Nyoman Kandun, said the two victims' 15-year-old sister, who was also hospitalized with high fever and respiratory problems, tested negative for H5N1. Kandun said for now, with only one confirmed case, human-to-human transmission could not be considered as a possibility.

Such cluster cases are closely monitored by authorities and specialists: there are fears that the virus may mutate into a form that can easily pass between humans. Experts have warned that human-to-human transmission – never proven as yet – could generate a pandemic with millions of deaths. According to the World Health Organisation, since bird flu first surfaced in Asia three years ago, it has killed at least 147 people across the world.