Tuesday, December 13, 2005

Continental cartogram and bird flu

CIDRAP ran a useful summary of human bird flu cases in China and Thailand the other day. China now has five officially reported and confirmed cases, but most anyone in the know (including the Chinese) think there are others, missed, overlooked or who knows what. See some posts here, here, here and here. The Thais have now reported five cases this year, but again, there are likely to be more. And Vietnam, of course, has reported the most cases. Indonesia is now third. (December 7 WHO case counts here). Indonesia had its ninth confirmed death and there will be more to follow:
Meanwhile, Ilham Patu, spokesman for Sulianti Saroso Hospital, the main center in Indonesia for bird flu treatment, told AFP that five new suspected bird flu patients were admitted overnight Monday and Tuesday from several areas of Jakarta.

"We have now a total of six patients being treated for suspected bird flu infections," Patu said.

He said some of the five admitted were in a worse condition than the sixth patient, a 23-year-old woman who has been under treatment in an intensive care unit at the hospital for the past few days. (Jakarta Post)
Since the virus is now on the wing and spreading to poultry populations in eastern Europe, Turkey and Russia, we have been asked why we shouldn't be concerned with Europe and perhaps North America as much as Asia, given migratory bird flyways span continents and it is probably only a matter of time before HPAI H5N1 reaches these regions as well.

The easiest answer can be seen in the map, below. It is a cartogram, a mapping device where regions are given areas proportional to their populations. This distorts their shape, of course, but allows one to see where the people are. The continental cartogram clearly shows that Asia is the place where the people are and it is also where most of the infected domestic birds are in close proximity to them.

So while it is certainly possible a viral strain, adapted to humans and easily transmitted from person to person, could arise anywhere in the world, the odds still favor Asia.