Monday, May 22, 2006

Until the Fat Lady sings

On a recent trip to a scientific meeting about something quite different than bird flu, several of my colleagues knowing of my interest in the disease wanted to know if this thing was finally over and the threat receding. This followed several optimistic news reports that Thailand and Vietnam have had few or no new cases this year and that their aggressive programs of combating the disease showed a pandemic could be avoided. Vietnam has used poultry vaccination, while Thailand has used area culling. WHO's flu czar Dr. David Nabarro has praised both countries and made cautiously optimistic sounds.

At the same time the largest cluster yet has occurred in Indonesia and the disease continues to spread uncontrolled in Africa. The latest case in that cluster is almost certainly an another example of person to person transmission. In Indonesia there is no aggressive program of any kind and two of the patients in the cluster were actually released from the hospital into the community and then readmitted to die. So much for the "fireblanket" and the computer models that suggested it was a possible strategy (also see our posts here, here, here and here):
As such, the Indonesian outbreak should serve as a stark reminder to all involved of the difficulties inherent in trying to translate the models' findings into reality, said infectious diseases expert Dr. Michael Osterholm.

"Our experiences with the virus during the last six months in Turkey, Iraq and now in Indonesia should give even the most ardent supporters of containment cause to realize why, while such an approach is an ideal, it also is a fantasy."

Osterholm has been skeptical since the modelling studies were published last summer that the optimistic outcome predicted by the work could be achieved outside of the hard drives of the computers on which they were devised.

"This was never about wanting to contain the virus. It's about the reality of what happens in everyday life," Osterholm said Saturday from Minneapolis, where he is director of the Center for Infectious Disease Research and Policy at the University of Minnesota.

"One of the problems models can't address is the impact of politics, fear, panic and lack of compliance on written guidelines for public health actions."

The models, by two international teams of scientists, suggested the WHO could contain an emerging pandemic if it discovered the virus was spreading among people within the first 20 human cases or within seven to 21 days of the start of transmission. (Helen Branswell, Canadian Press)
Last week Maryn McKenna, the Atlanta Journal Constitution's expert flu reporter, had an excellent story about the difficulties of predicting what flu is going to do. The whole things is worth a read, but here is the pertinent point:
After the Asian strain of bird flu attacked humans for the first time in Hong Kong in 1997 --- sickening 18 people and killing six of them --- it disappeared for several years. It surfaced briefly in Hong Kong in 2003, infecting two people and killing one, and then vanished again for almost a year before resurfacing in Thailand and Vietnam.

Similarly, though the virus at first spread rapidly --- causing 22 cases and 15 deaths in Vietnam by the end of February 2004, and 12 cases and eight deaths in Thailand by the end of March --- it subsequently went underground again. Five months passed before Vietnam saw another human case; in Thailand, the gap was six months.

Those gaps, like the current one, occurred as the weather warmed. Influenza is seasonal: It flourishes during winter months --- or in the rainy season in tropical countries that have no clearly-defined winter --- and disappears in the summer, said Dr. Bruce Ribner, associate professor of infectious diseases at Emory University School of Medicine.


Dr. D.A. Henderson of the University of Pittsburgh Medical Center's Center for Biosecurity, former leader of the international campaign to eradicate smallpox, warns that too little is known about the Asian avian flu.

"I don't think we can feel at all confident that because flu appears to be at a lower level in some countries it is not still spreading, at least in birds," said Henderson, who worked early in his career on the 1957 influenza pandemic that killed 70,000 Americans and about 2 million people around the world.

Behind health authorities' questioning of the Southeast Asian case numbers lies a fear that success will lead countries to drop their aggressive efforts against the virus --- a concern reinforced by memories of Thailand and Vietnam declaring premature victory against the virus in March 2004.

"We have to walk a fine line between continuing to aggressively prepare for a flu pandemic, and at the same time recognizing that people's attention span will wane if the H5N1 situation looks less threatening," [CDC Director Dr. Julie] Gerberding said. (Maryn McKenna, Atlanta Journal Constitution)
As if to underline the concern, China's vice Premier Hui Liangyu said Saturday he remained concerned about the bird flu situation in China and elsewhere:
“Summing up and analyzing the epidemic’s current development both inside and outside the country, the . . . situation is not optimistic,” Hui said at a national meeting on the prevention and control of avian flu.

His warning came as the agriculture ministry reported Saturday that a total of 308 wild migratory birds have died since a bird-flu case was reported in the northwest province of Qinghai on April 23.

As of Friday, 300 bar-headed geese and eight birds of other species had been found dead in the remote province, a statement on the ministry’s website said. (AFP via Manila Times)
Yogi Berra, relying on his deep knowledge of the opera once said, "It ain't over till the fat lady sings." Of course what happens after the fat lady sings is "curtains." (NB: This is not a prediction! It's just a way to finish off this post. You'll still have time to buy your personal 5000 gallons of bottled water later. Meanwhile contact your water utility and ask them if they have made any plans in case there's a pandemic.)