The Coming Influenza Pandemic?

November 19 Flu Update--More Flu in China

Studies of past pandemics don't reveal how the switchover from bird virus to human scourge will happen in the next one. Instead, they illustrate there are two routes. The virus can make the genetic changes on its own. Or it can pick up genes from a human flu virus, perhaps in a person who became infected simultaneously with the bird and human viruses. This gene-swapping process is called reassortment.

Taubenberger, who is studying the genetic makeup of the 1918 pandemic virus, said that germ appears to have mutated on its own. In contrast, the viruses behind the other two pandemics of the 20th Century were apparently products of reassortment, he said.

Beijing is desperately trying to educate its local officials and health officers about the realities of the disease, but the first instinct of many Chinese bureaucrats is to conceal and cover up. The greatest danger is that those same bureaucrats might even conceal a case of human-to-human transmission, the potential trigger of a global bird-flu epidemic that could kill millions of people.

After repeated denials, China finally confirmed its first human cases of bird flu this week, including two deaths where bird flu is confirmed or strongly suspected.

Evidence of a cover-up has already emerged in at least two regions of China. In Hunan province, reporters were arrested when they tried to investigate rumours of a bird-flu outbreak. Officials declared last month that the case was "closed," and then were forced to admit this week that the outbreak was indeed caused by bird flu.

In Liaoning province, where three bird-flu outbreaks have erupted, it was revealed this week that a bureaucrat has been arrested for trying to cover up the illnesses of chickens at local farms.

Zhao Yonghe, head of veterinary services in a village in Liaoning, was allegedly giving certificates to local farmers to verify that their chickens were healthy, though he knew they had contracted the bird-flu virus.

Lubroth says China's slowness to share viruses reflects a concern there that the country's researchers do not receive adequate credit for their scientific contribution.

Brown can understand that point of view, saying scientists the world over hoard their data in order to ensure they get credit for their findings, which is key to ensuring ongoing research funding.

"You don't give away your data because the big labs will take it, they'll take the credit and you're sitting there writing a grant application without having the work published by yourself," he says.

Firstly, although the majority (but not all) of the human cases can be related to contact with diseased poultry, the number of human cases of illness must be a very small proportion of all contacts between humans and diseased poultry. Other as-yet-unrecognized factors must be involved.

Secondly, nucleotide sequence analysis is useful in unravelling the epidemiology of separate outbreaks. But sequence variation has to be correlated with biological experiments to make predictions about the imminence of changes in transmissibility and virus virulence. Mutations tend to be deleterious unless there is some external selective pressure favouring survival of a particular phenotype.

posted by Orange @ 8:49 PM