Ground zero for bird flu?
Will Turkey add an ironic twist to its name and become the place that gave bird flu to the world? It is not a scenario the experts tracking the disease were expecting. While nobody can predict where bird flu will mutate into a human-to-human contagion, 'if I had to put money on it, it would be Asia', said Michael Ryan, the World Health Organisation's chief of emergency response, in November.
There are six official cases in Turkey, but many more being investigated. It is approaching the eight cases in China and 16 in Indonesia - the two places that have been thought most likely to breed a human bird flu 'supervirus'. But does this really mean Turkey is bird flu ground zero?
So far, tests on Turkey's human cases have shown that they have the bird virus: it has not yet made the feared transition to a human strain. However, the number of cases there is not good news. The virus may be getting better at directly infecting both humans and chickens. Or it may be that the Turks are picking up more cases.
Recent studies from Japan and Vietnam suggest that many more people get infected with bird viruses than we realise.
The Japanese have been testing their poultry workers for several years. In 2004, they found very low levels of antibodies to the deadly H5N1 strain of bird flu in a handful of healthy workers who had culled infected birds.
This week, the Japanese Ministry of Health announced it had detected antibodies to the H5N2 strain - a milder poultry infection that went through Japanese flocks last year.
In Vietnam, a team from Sweden's Karolinska Institute surveyed families in villages that had the H5N1 bird flu strain in their poultry flocks, and found that about 20 per cent reported suffering a flu-like illness. This suggests there are many more cases than are being detected. However, there is another, more sinister interpretation of the findings in Vietnam.
That country may have been experiencing a lot of human influenza in April and May last year - the peak months in neighbouring Hong Kong - along with bird flu. The Swedish team may have uncovered the scenario that the WHO fears most: the villagers' symptoms could have been from human flu strains, meaning there were high levels of the human influenza virus circulating with high levels of the bird flu virus.
Such conditions increase the likelihood of a person being infected by the human and bird viruses at the same time. They would unwittingly host a 'doomsday marriage' - when two viruses meet in the same cell and swap genetic material, producing a 'superflu' strain.
Will this happen in Turkey first? It is possible. The conditions are ripe: the country has lots of birds and humans living together, cold weather keeping the virus alive, a repressive government not trusted by its people, and widespread poverty.
But those conditions can be found in much of mainland China, too.
While China's cases seem to be increasing slowly, it should be remembered that getting Beijing to acknowledge the first case was like pulling teeth.
Unofficially, we know of at least one earlier case: that of a Hong Kong family whose daughter died on the mainland in 2003. When the family returned to Hong Kong, the father (who died later) and son tested positive for H5N1.
While mainland China has been slow to detect human cases, it is catching up: we get daily reports, now, on a 10-year-old Hunan boy fighting for life.
Because it is a cold-weather virus, will the warmer months give us some breathing space? Judging from last year, that seems unlikely. Outbreaks occurred sporadically in poultry flocks in Vietnam and Indonesia - which never gets very cold - throughout the year.
Margaret Cheng is a Hong Kong-based medical writer
