CDC Director Gerberding Cites Avian Flu As "Very Ominous" Threat

Avian flu, which has killed millions of birds and several dozen people in Asia, poses a "very ominous" threat to humans worldwide, the top doctor at the U.S. Centers for Disease Control warned yesterday.

In an address to the AAAS Annual Meeting in Washington, D.C., Dr. Julie Louise Gerberding noted that the in its current form poses a relatively limited problem for humans. But, she said, the current situation "probably" resembles the period before the 1918 Spanish flu outbreak when the virus was quietly mutating into a strain that would eventually leave 50 million people dead.

"Most people who are looking at this recognize it is a very ominous situation for the globe in terms of statistical probability" of a larger outbreak among humans, Gerberding said.

Gerberding's comments Monday came just a day after Dr. Nancy Cox, the CDC's chief influenza scientist, suggested to a AAAS audience that further mutation in the avian flu in Asia could precipitate the worst pandemic in human history.

Researchers believe that prolonged contact with infected birds or consumption of raw, infected chicken meat is required for the virus to jump to humans. But once it does make the jump, it appears to be lethal: According to a report Monday in the Financial Times, the current outbreak has infected 55 humans in Asia and killed 42, a mortality rate of 76 percent.

The fear is that the virus would mutate in such a way that it becomes easier to pass from human to human, without losing any of its lethal force. An Oxford research team recently reported that the virus is adapting to attack mammals.

Today's H5 strain, Gerberding said, "has already evolved from the H5 of a few years ago."

"The concern in Asia," she explained, "is that we have this highly pathogenic strain of influenza, circulating widely, and there are really wonderful opportunities for this virus to either reassort (its genes) with human strains of influenza, or with other avian species, and evolve into a strain is that has whatever that secret ingredient is that allows it to be effectively transmitted from person to person."

A recent study published in the New England Journal of Medicine reported that the disease had spread to two Vietnamese children without showing the usual respiratory symptoms. Both of them died. It's also possible that the mortality rate is lower because some cases of avian flu in humans are not being reported or even recognized because they do not lead to death.

Gerberding was named as CDC director in July 2002; she also serves as administrator of the Agency for Toxic Substances and Disease Registry. In her address Monday, she noted that her agency has been dealing with crisis almost continually since the terrorist attacks of 11 September 2001.

Since then, the CDC has had to deal with mail-borne anthrax attacks, SARS, monkey pox, mad cow disease, avian flu, West Nile virus, the unexpected shortage of flu vaccines, hurricanes and the Asian earthquake and tsunami.

Of the 13 most recent emerging disease outbreaks, 12 have been zoogenic, or originating in animals, Gerberding said.

Because virus can mutate and spread so quickly, there is a premium on finding viruses that emerge even in remote parts of the world, keeping them under surveillance, and being prepared to intervene if they jump to humans.

"We have to be incredibly fast communication and we have to have, most importantly, fast action," she said. Currently the CDC can tap into medical data that's just days old, but "if this were SARS or avian flu," she added, "that would not be fast enough."

Gerberding said some of the response plan is modeled on disrupting "small world networks"-by limiting the movements of people who might be carrying the virus, for example, or possibly even order quarantines. The effort requires increasingly refined communications efforts, she said, so that people are informed and persuaded to alter their behavior without causing unnecessary disruptions or panic.

International cooperation also is crucial, and she cited the efforts of Thailand and Vietnam as helpful in the current campaign.

"A problem in a remote corner of the world becomes a world problem overnight," she said. "A world problem quickly becomes a local problem, in every corner of the world."

— Edward W. Lempinen

21 February 2005