Saturday, December 08, 2007

The Pecking Order Has Changed

It appears that avian flu has begun its migration to mammals:
The father of a Chinese man who died of bird flu has also been infected with the virus, raising fear of human-to-human transmission.

The World Health Organization said it could not rule out the possibility that the H5N1 virus had spread from the son to the father.

For the most part, humans have caught the virus from sick birds.

Scientists fear if the virus gains the ability to pass easily between humans, tens of millions of people could die.

A statement on the Chinese ministry's website said a 52-year-old man in eastern Jiangsu province identified only by his surname, Lu, has been confirmed with the virus, just days after his 24-year-old son succumbed to it on 2 December.
Members of the same family have died before, but it's been difficult to tell whether it was human-to-human contagion or contact with affected birds, since the family members have all had interactions with their bird stock.

In this case, however, there is no clear non-human link to the virus, ratcheting up the probability of mammalian adaption by the virus. If so, we're talking about the possibility of an outbreak at least as severe as the Hong Kong Flu of 1968, and perhaps as virulent as the Spanish Flu of 1918.

In both cases, it took from seven to ten years between the first recognized avian outbreak until the virus became activated in mammals. In the case of the Hong Kong flu, it skipped the intermediate mammalian outbreak to attack humans directly, so we might not get a warning when the avian flu epidemizes.

Ironically, the Hong Kong flu hit American shores from returning troops ending their tours of duty in Viet Nam, and here we are, debating ending yet another war in Asia and bringing troops home. Osama might be rubbing his hands in glee.

The death rates for the Hong Kong flu were low. Of 50 million reported cases in the US, for example, 33 thousand people died. The death rates for the Spanish flu were tragically high: 50-100 million estimated dead, with about twice that number reporting the disease (or symptoms just like records are incomplete).

Right now, the avian flu mortality rate is skewing towards the high end of this scale. For example, in China, 26 cases have been reported, with 17 fatalities. A total of 200 people worldwide have died of the avian flu.

And then there's Ebola...