WHO probes possible human-to-human bird flu
Tue May 23, 2006 8:03 PM BST
By Richard Waddington
GENEVA (Reuters) - The World Health Organisation (WHO) said on Tuesday human-to-human transmission of bird flu could not be ruled out in the deaths of six Indonesians.
The virus has not mutated to become more dangerous, the WHO emphasised. So far, virtually all the world's 124 human victims of bird flu, most of them in Asia, have caught it from poultry.
But the deaths of the Indonesian family group, one of the largest clusters seen since the disease re-emerged in 2003, triggered fears the virus could be evolving into a type that could easily jump from person to person.
Scientists say millions of people could die if the virus acquires this ability, perhaps by hooking up with a common flu strain.
But the WHO said in the Indonesian cases there was no sign of mutation of the virus or rapid spread of the disease across a community that could indicate an epidemic was in the making.
"Sequencing ... found no evidence of genetic reassortment ... and no evidence of significant mutations," the United Nations health agency said in its statement.
However, given that those infected lived in close proximity in a village in North Sumatra and that some had cared for sick relatives before falling ill themselves, it was possible that humans were the source of infection at least in some instances.
"All confirmed cases in the cluster can be directly linked to close and prolonged exposure to a patient during a phase of severe illness," the WHO said.
"Although human-to-human transmission cannot be ruled out, the search for a possible alternative source of exposure is continuing," said a statement on its Web site, which made clear there had been no "efficient" human-to-human transmission.
The agency believes some human-to-human transmission has occurred before in other countries, but as in the Indonesian case, laboratory tests have given no indication of the feared mutation that would make the virus easier to catch and spread.
NO EVIDENCE
"To date, the investigation has found no evidence of spread within the general community and no evidence that efficient human-to-human transmission has occurred," the WHO said.
Tests done in WHO-affiliated laboratories in Hong Kong and the United States on eight segments of virus taken from the Indonesian family members showed no sign of genetic reassortment -- the scientific term for when chunks of viruses combine.
Nevertheless, the WHO said it was concerned at the situation in the Indonesian village of Kubu Simbelang, where the outbreak took place, and together with the Indonesian Health Ministry it was stepping up the search for possible additional cases.
Seven members of the extended Indonesian family are known to have caught the disease, and six have died.
The WHO says there was probably an eighth case, a woman who died, but no tests were carried out.
Epidemiological evidence suggests that the woman was in fact the first case and that three family members spent at least one night in a small room with her at a time when she would have been coughing frequently, the WHO said.
H5N1 has picked up speed this year, moving into parts of Africa, the Middle East and Europe. Bird flu remains primarily an avian disease.
In the past five months alone, more than 30 countries have reported outbreaks in poultry or wild birds and more people have died than in the whole of last year.
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