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William J Kole
13 Jan 2006 16:05
The deadly H5N1 strain of bird flu could be passing from person to person in Turkey even though health experts have no evidence that the virus is spreading that way, a senior World Health Organisation (WHO) expert said on Thursday.
Guenael Rodier, the WHO’s head of communicable diseases and response, said experts cannot rule out person-to-person infection because “we haven’t documented each and every case properly”.
“When you have a mother and a child, and both get sick, you don’t know if they both were exposed to the chickens or if the mother got sick because she was caring for the child,” Rodier said. “It leaves room for some question marks.
We have not documented every transmission story.”
But he said that even if human-to-human contact is established, it could end up being contained within families and not necessarily trigger the pandemic that experts fear could kill millions.
Preliminary tests have confirmed H5N1 in 18 Turks, including three children who died last week.
“The virus could spread like Sars [severe acute respiratory syndrome] and still be contained,” Rodier said, referring to outbreaks of Sars in 2002 and 2003.
Experts have said that all the cases appear to have involved people who touched or played with infected birds, and there is no hard evidence pointing to direct infection between people.
“At the moment, there is absolutely no element that makes me think this is the case,” Rodier said.
The WHO said on Thursday that an analysis of H5N1 samples from two Turkish victims has detected a change in one gene in one of two samples tested, but that it is too early to tell whether the mutation is significant.
The mutation, which allows the virus to bind to a human cell more easily than to a bird cell, is a shift in the direction of the virus being able to infect people more easily than it does now, the agency said.
“The lab people are not so alarmed,” Rodier said on Friday, adding that further analysis is needed to determine how the virus might be evolving. “If there are implications, we will see them.”
“It could mean a lot of things. Finding something in the [genetic] sequence is not necessarily linked to something in the field,” he added.
The United Nations health agency has said it is not alarmed by the finding in a single virus sample because this exact genetic change has been seen before, in samples from southern China in 2003, and it had no impact on the course of the disease, the behaviour of the virus or the pattern of human infections.
An official from the UN Food and Agriculture Agency said on Friday that the Turkish mutation occurred in one of the children who died a week ago in the first H5N1 fatalities documented outside East Asia.
The shift in the gene is very small and there is no cause for concern, said the official, who spoke on condition of anonymity because he was not authorised to speak to reporters. The virus in Turkey displayed a 99,5% similarity to the strain that surfaced in birds in China’s northwestern Qinghai province, and a 99,2% similarity to the flu detected in Russia’s Novosibirsk region in Siberia, he said.
Rodier said the WHO has asked Turkey’s health ministry for permission to conduct more intensive screening in villages in the areas where outbreaks have occurred, and that the proposal includes plans for blood tests, throat swabs and interviews with families.
Patients seem to be responding well to the antiviral drug Tamiflu, he said.
Some experts have expressed concern that H5N1 could become entrenched in Turkey, and that a permanent presence of the strain on the rim of Europe would pose a serious threat to the rest of the continent as well as to Africa, since the country lies on a major migratory route for wild birds.
Rodier said he could not say whether H5N1 would become endemic to Turkey, but he conceded: “We are expecting this constant threat for months to come.”—Sapa-AP
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