Sunday, December 05, 2004

More on H5N1 and why we worry

The news reported in yesterday's post below about the French suspect case is good. It wasn't H5N1 influenza. But not all the news is so cheery. The Poultry Diseases site kept by Dr. Nati Elkin has a good rundown of the latest science involving this bird-reservoir virus and others like it (such as the H7N7 strain which can also infect humans. But be aware of annoying pop-ups on this site!). Among the items:
  • Domestic and wild ducks can host the virus without becoming sick and they excrete large amounts through their respiratory tracts and feces and can pass on the infection to chickens
  • Ducks shed H5N1 viruses isolated in 2004 for 11 to 17 days or longer compared to a maximum of 10 days for 2003 isolates. The virus remained viable in the environment at 37 degrees C. (body temperature) for 6 days compared to only 2 days for 1997 isolates
These studies done at St.Jude Children's Research Hospital in Memphis, TN were released at the end of October prior to publication because of their significance for human health They suggest not only longer persistence in a migratory animal reservoir, ducks, but a genetic drift towards more stability. Poultry Diseases report here.

This follows on widely reported information of similar significance from last spring that the H5N1 virus was finding new mammalian hosts, in this case domestic cats. While it is not clear that cats are an important vector in spreading the disease (they shed the virus less than ducks), this again suggests the H5N1 strain is changing genetically and becoming adapted to mammals. Original article in the journal Science, Vol 305, Issue 5689, 1385.

Clearly the sensitivity of health authorities to suspected human cases like the one reported in France last week is prudent.

Update: The Times in Hong Kong is reporting that the Chinese government is taking the possibility of an impending avian flu outbreak with extreme seriousness:
BEIJING has drawn up a far-reaching plan to combat a bird flu epidemic that could kill tens of millions of people, The Times has learnt.

The plan, which has not been published, involves curtailing travel to prevent the virus being carried around the country and envisages emergency measures to ensure supplies of food, energy and other essential services.


“China is taking the threat of a pandemic very seriously,” said Julie Hall, a WHO adviser in Beijing, who has seen the broad outlines of the country’s contingency plan.

“We attach great importance to fighting bird flu. We haven’t closed our eyes for a single day,” a spokeswoman for the Chinese Centre for Disease Control, a central government body, said.


Qi Lei scares the Chinese Government more than any foreign enemy — and he does not even know it. The skinny 38-year-old coalman cycles into central Beijing every morning from his shed in the countryside to deliver coal bricks stacked on the back of his rusting tricycle. “I ride around with no fixed destination, just wherever people need coal to heat their homes,” he said.

What really frightens Beijing is what else Mr Qi might bring with him from the farm villages of Hebei province, a prime breeding ground for the bird flu virus. Unregulated traffic from rural to urban areas as practised by Mr Qi is the most likely transmission route, as it was with the spread of the Sars virus, and one of the first things the Government would want to do is curtail movement from rural to urban areas.

The Chinese believe neither stockpiling any vaccine that might be available (and as yet there is none for H5N1) or flooding the area with medical workers, will stop the spread of influenza in a country of its size. Both vaccine supplies and medical care will soon be overwhelmed.
Essential services such as burials would be carried out by special government squads, possibly involving the army. “If 10,000 people died in one day, I wouldn’t know what to do,” Peng Zong, a director of a private undertakers, said.

Sites for mass graves have been identified and quietly cordoned off to avoid the spread of other diseases, one official said.

Another big concern is the supply of food, and Beijing has drawn up lists of emergency food depots. Citizens waiting out the pandemic in their homes would be informed by vehicle-mounted loudspeakers how to access food supplies. It is assumed that access to media would be curtailed either for lack of electricity or because of the closure of all public buildings, including the state television studios. During the Sars crisis last year, Beijing was criticised for acting belatedly and sloppily, and the WHO has repeatedly pressed China and other Asian countries to step up their anti-disease campaigns.