Jakarta (AsiaNews/Agencies) –The World Health Organisation (WHO) today concluded that seven relatives who died from bird flu last month on Indonesia's Sumatra Island were most likely infected by human-to-human transmission.

However WHO experts added that human-to-human transmission was not attributable to mutations of the virus and there were no signs to indicate that this was the first step towards a global pandemic.

Doctors said one member of the family first contracted the virus from infected birds and then transmitted it to the other six. One of them, a boy, in turn infected the father.

The case findings were distributed at a closed meeting in Jakarta attended by some of the world's top bird flu experts. The three-day session, that wrapped up today, was convened after the Indonesian government asked for international help. The country has recorded the world's highest number of cases of H5N1 infection this year, and 39 of those infected have died.

One of the remaining doubts to be cleared is why only blood relatives – not spouses – became infected. Some WHO experts held that the family – in the strict sense of the word – "shared a common genetic predisposition to infection with H5N1 virus with severe and fatal outcomes". But there is no evidence to support that. Indonesia remains a key concern in the global bird flu scenario. In another worrying sign, an animal health expert said he had discovered outbreaks in Indonesian poultry were vastly underreported. Jeff Mariner, who works with the UN Food and Agriculture Organisation (FAO) on a pilot project with local teams, researches health of poultry. Mariner analyzed 12 districts on Java Island from January to May and detected 78 outbreaks of infection.

On the sidelines of the meeting, he said he had never imagined how common under-reporting of cases was. "These numbers of outbreaks only represent, say, a third of the coverage in the district."