Editor's note: An earlier version of this story incorrectly said the World Health Organization had established human-to-human transmission of the bird flu virus in Pakistan. Actually, officials say no evidence has been found of that although a single case of the H5N1 virus has been established in a sick family.
The World Health Organization said on Thursday it had established a single case of human infection of the H5N1 bird flu virus in a sick family in Pakistan but there was no apparent risk of it spreading further.
A statement from the U.N. agency said tests in its special laboratories in Cairo and London had established the “human infection” through presence of the virus “collected from one case in an affected family.”
But it said a WHO team invited to Pakistan to look into an outbreak involving up to nine people from late October to December 6 had found no evidence of sustained or community human-to-human transmission.
No identified close contacts of the people infected, including health workers and other members of the affected family, had shown any symptoms and they had all been removed from medical observation, the WHO added.
The outbreak followed a culling of infected chickens in the Peshawar region, in which a veterinary doctor was involved. Subsequently he and three of his brothers developed proven or suspected pneumonia.
The brothers cared for one another and had close personal contact both at home and in hospital, a WHO spokesman in Geneva said. One of them, who was not involved in the culling, died on November 23, but the cause of death was not known.
On November 28 another brother who had not been involved in the culling died, and tests on him — in Pakistan as well as in Cairo and London — had established the presence of the H5N1 virus.
The WHO spokesman said there was suspicion that there had been human-to-human transmission — as there had been similar suspicion of such transmission within families in Thailand, Indonesia and Vietnam — but this could not be confirmed.
Last week, WHO assistant director-general for health security and environment David Heymann told a Geneva news briefing that an investigation team in Pakistan “feels that this could be an instance of close contact human-to-human transmission, just like happened in Indonesia and Thailand.”
The WHO spokesman told Reuters on Thursday all the evidence ”suggests that the outbreak within this family does not pose a broader risk. He added: “But there is already heightened surveillance and there is a need for ongoing vigilance.”
Global health experts fear the virus — which has killed 212 people out of 343 infections reported since 2003 — could mutate into a form that spreads easily from one person to another, possibly triggering a pandemic that could kill millions.