Bird flu in Turkey raises questions on spead of the disease

Three people have died and 12 others have been infected in an outbreak of avian flu in Turkey this week; the dead, all children from the same family, are the first bird flu deaths outside of Asia. While the relationship between the dead children has raised concern that the virus may be transmmitted from human-to-human, the evidence still suggests this is a case of animal-to-human infection, as reported by the BBC News:

Mehmet Ali Kocyigit, 14, and his two sisters Fatma, 15, and Hulya, 11, have all died this week.

Tests carried out in a UK laboratory confirmed that Mehmet Ali and Fatma died from the H5N1 strain, which has killed more than 70 in south-east Asia and China.

The children’s family kept poultry at their home in Dogubeyazit, close to the Iranian border in Van province.

All four children developed symptoms including a high fever, coughing and bleeding in the throat.

Doctors said they had been playing with the heads of chickens who had died of bird flu.

There is concern by health officials that the concentration of victims may suggest, however, that a strain of H5N1 is circulating that is easier to pass to humans. While this is not the human-to-human mutation required that could lead to a pandemic, it is a serious concern for populations in close proximity to infected (or potentially infected) poultry. Since January 2004, more than 140 cases linked to bird flu have been reported to WHO. More than half the patients died. The WHO is concerned by developments in Turkey but not ready to raise the global alert level at this point, according to spokesperson Dr. Maria Cheng:

Cheng said at this point the WHO isn’t contemplating changing the global pandemic alert status from the current Phase 3 (no or rare instances of person-to-person spread) to Phase 4, where small, localized clusters of cases indict limited human-to-human spread – a development that would suggest the virus is adapting to a human host.

“We’re still at a very preliminary stage in the outbreak investigation. And to move from (Phase) 3 to 4 we’d have to see a substantial change in the virus to know that it’s becoming more adapted to human transmission,’’ Cheng said.

She added that at this point, the WHO doesn’t think the virus is passing from person to person in Turkey.

“Our hypothesis is that we know that this is an area where people raise chickens and that there tends to be a lot of contact between people and chickens,” she said.

“So I think our working hypothesis is that they contracted disease through common exposure. But at the same time we can’t rule out human-to-human transmission.”

Two concise but very informative posts by Revere have appeared here and here on the public health blog Effect Measure that provide a useful update on the situation in Turkey and the possible implications.

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