Flu pandemic alert unchanged
Members of an Indonesian family who died of bird flu probably passed the disease among themselves, but world health officials said there was no evidence the virus had mutated and decided against raising the pandemic alert level.
At least six people died and one was infected – the largest family cluster of bird flu cases likely transmitted from person to person since the virus started ravaging poultry stocks across Asia in 2003, said World Health Organisation spokesman Gregory Hartl.
Though other cases of very limited human-to-human transmission have been documented, a top US health official said yesterday that this may mark the first time bird flu has passed from person to person to person.
Previous clusters all involved someone who was infected by a sick bird and then spread the virus to others. This new cluster appears to involve a cascade of transmission, said Dr Julie Gerberding, director of the US Centres for Disease Control and Prevention.
The family members’ close physical proximity is probably responsible for the spread of the disease, Hartl said.
“It fits the kind of pattern perfectly which we’ve seen so far,” Hartl said in Geneva. Global and US health officials say tests on virus samples taken from the family do not indicate any significant changes.
Bird flu has killed 124 people worldwide, more than a quarter of them in Indonesia. So far, most human cases have been traced to contact with infected poultry.
Experts have long believed the virus is spread when people breathe it in - possibly in dust from bird droppings or in droplets sneezed or coughed by humans into the air.
But it remains unclear exactly how the virus spreads in family groups - whether through respiratory systems, food, infected surfaces or a combination of these, Hartl said.
“Which transmission mode is most important, we really don’t know yet,” he said. “When you get all of these things together, it becomes perhaps more likely.”
Other experts have suggested family members have a genetic weakness to the disease. In all four family clusters recorded so far, only direct blood relatives – not spouses – have caught bird flu.
WHO will leave its pandemic alert level unchanged at 3, where it has been for months, meaning there is “no or very limited human-to-human transmission”.
Six of the seven family members who caught bird flu have died, the most recent on Monday. An eighth family member who died was buried before tests could be done, but she was considered to be among those infected with bird flu.
Investigators say the family, living in the remote northern Sumatra village of Kubu Sembelang, was infected with a strain of H5N1 bird flu that was genetically the same as the virus found circulating in the area earlier.
Tests are still being carried out on poultry there.
Health workers have found no sign the latest Indonesian case has moved outside the family, and there is also “no evidence that efficient human-to-human transmission has occurred,” WHO said in a statement.
Still the size of the cluster and the failure to determine the source of the infections was worrying, Peter Cordingley, spokesman for WHO’s Western Pacific region.
“We have a team … examining what is going on and they can’t find an animal source of this infection,” he said, adding that they were “completely stumped.”
Meanwhile, an outbreak of bird flu has been found in migratory birds in a remote area of western China, the government says.
The case occurred in an isolated area of Tibet and neighbouring Qinghai province on a same migration route where other wild birds died in an outbreak in late April, the Agriculture Ministry said late yesterday.
A total of 399 birds have been found dead in the two outbreaks in an isolated area high on the Tibetan plateau with few people and no domestic poultry, the ministry said in a statement carried by the official Xinhua News Agency.
The earlier outbreak affected mostly bar-headed geese. The government didn’t say what type of birds were involved in the latest case.
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