Thursday, August 18, 2005

Avian Flu update

Lots of stuff coming in...

The Next Pandemic?
A special section in the July/August 2005 issue of Foreign Affairs.

Editor's Note
As a call to action, the July/August issue of Foreign Affairs includes a special set of articles..

AN OUTBREAK of avian flu among wild and domestic birds in Russia is spreading west and starting to approach Europe, public health officials said yesterday.
The first cases of bird flu have been reported in the Chelyabinsk region of Siberia, close to the Ural mountains that separate Europe from Asia, though scientists are not yet certain that the virus found there is the deadly H5N1 strain.
Roads were cordoned off and hundreds of chickens were slaughtered in Chelyabinsk yesterday to contain the apparent advance of avian flu, first reported in Siberia in July and being spread westward by migrating birds.
[More from the Times of London]

The CDC predicts that a "medium-level epidemic" could kill up to 207,000 Americans, hospitalize 734,000, and sicken about a third of the U.S. population. Direct medical costs would top $166 billion, not including the costs of vaccination. An H5N1 avian influenza that is transmittable from human to human could be even more devastating: assuming a mortality rate of 20 percent and 80 million illnesses, the United States could be looking at 16 million deaths and unimaginable economic costs. This extreme outcome is a worst-case scenario; it assumes failure to produce an effective vaccine rapidly enough to make a difference and a virus that remains impervious to some antiflu drugs. But the 207,000 reckoning is clearly a conservative guess. [Laurie Garrett, Senior Fellow for Global Health at the Council on Foreign Relations and author of The Coming Plague and Betrayal of Trust writing in Foreign Affairs. Very long. See addendum below.]

Thanks Hugh Hewett and Stones Cry Out

A blog was started at the end of March, Avian Flu - What we need to know, for the purpose of keeping up with Avian Flu. There have been posts almost daily. Good one to bookmark or add to the aggregator.

It's two days later and I have read through that Laurie Garrett paper cited above. It prints out to ten pages if you stretch the margins and use two column format. Pretty long.

There are a lot of if's, buts, mays and possiblies in the thing which makes it clear that there is no way to know with any kind of assurance what may happen. It's like predicting the big one in California, or speculating about the odds of an asteroid hitting earth. The difference is that big ones and asteroids don't seem to occur with the frequency of pandemics, so I would be careful not to dismiss the threat lightly.

If the president is reading about the great flu outbreak of 1918 I would guess he is weighing the political aspects of what could happen if there is a global disaster and he did too little, against another Y2K puff that triggered what turned out to be an unfounded exercise in overkill. Shades of duck and cover! The article suggest that any catastrophe that manifests could happen this next season or... and this strikes me as more could continue to loom for several years to come. The longer the delay, the less likely will be a political will that might cause anything constructive to be pushed through, either by Congress or by some future administration.
Snips that struck me as interesting... of May 1, about 109 people were known to have contracted it, and it killed 54 percent (although this statistic does not include any milder cases that may have gone unreported). Since it first appeared in southern China in 1997, the virus has mutated, becoming heartier and deadlier and killing a wider range of species.

... in a normal flu season about 200,000 Americans are hospitalized, 38,000 of whom die from the disease, with an overall mortality rate of .008 percent for those infected.
[In the event of a global disaster] the international community would look to the United States, Canada, Japan, and Europe for answers, vaccines, cures, cash, and hope. How these wealthy governments responded, and how radically the death rates differed along worldwide fault lines of poverty, would resonate for years thereafter.

Nearly half of all deaths in the United States in 1918 were flu related. Some 675,000 Americans -- about 0.6 percent of the population of 105 million and the equivalent of 2 million American deaths today -- perished from the Spanish flu. [Statistics are incomplete. Many people perished in what we now refer to as the Third World.]... many historians and biologists believe that nearly a third of all humans suffered from influenza in 1918-19 -- and that of these, 100 million died.

Most strains of the flu do not kill people directly; rather, death is caused by bacteria, which surge into the embattled lungs of the victim. But the Spanish flu that circulated in 1918-19 was a direct killer. Victims suffered from acute cyanosis, a blue discoloration of the skin and mucous membranes. They vomited and coughed up blood, which also poured uncontrollably from their noses and, in the case of women, from their genitals. The highest death toll occurred among pregnant women: as many as 71 percent of those infected died. If the woman survived, the fetus invariably did not. Many young people suffered from encephalitis, as the virus chewed away at their brains and spinal cords. And millions experienced acute respiratory distress syndrome, an immunological condition in which disease-fighting cells so overwhelm the lungs in their battle against the invaders that the lung cells themselves become collateral damage, and the victims suffocate. Had antibiotics existed, they may not have been much help.

Influenza viruses contain eight genes, composed of RNA and packaged loosely in protective proteins. Like most RNA viruses, influenza reproduces sloppily: its genes readily fall apart, and it can absorb different genetic material and get mixed up in a process called reassortment. When influenza successfully infects a new species -- say, pigs -- it can reassort, and may switch from being an avian virus to a mammalian one. When that occurs, a human epidemic can result.

From 1998 to 2001 the virus went through multiple reassortments and moved back to domestic birds, spreading almost unnoticed in Chinese chicken flocks. It continued to evolve at high speed: 17 more reassortments occurred, and in January 2003 the "Z" virus emerged, a mutant powerhouse that had become tougher, capable of withstanding a wider range of environmental challenges. The Z virus spread to Vietnam and Thailand, where it evolved further, becoming resistant to one of the two classes of antiflu drugs, known as amantadines, or M2-inhibitors.

Over the course of this brief but rapid evolution, the H5N1 virus developed in ways unprecedented in influenza research. It is not only incredibly deadly but also incredibly difficult to contain. The virus apparently now has the ability to survive in chicken feces and the meat of dead animals, despite the lack of blood flow and living cells; raw chicken meat fed to tigers in Thailand zoos resulted in the deaths of 147 out of a total of 418. The virus has also found ways to vastly increase the range of species it can infect and kill. Most strains of influenza are not lethal in lab mice, but Z+ is lethal in 100 percent of them. It even kills the very types of wild migratory birds that normally host influenza strains harmlessly. Yet domestic ducks, for unknown reasons, carry the virus without a problem, which may explain where Z+ hides between outbreaks among chickens.

The medical histories of those who have died from H5N1 influenza are disturbingly similar to accounts of sufferers of the Spanish flu in 1918-19. Otherwise healthy people are completely overcome by the virus, developing all of the classic flu symptoms: coughing, headache, muscle pain, nausea, dizziness, diarrhea, high fever, depression, and loss of appetite. But these are just some of the effects. Victims also suffer from pneumonia, encephalitis, meningitis, acute respiratory distress, and internal bleeding and hemorrhaging. An autopsy of a child who died of the disease in Thailand last year revealed that the youth's lungs had been torn apart in the all-out war between disease-fighting cells and the virus.

The scarcity of flu vaccine, although a serious problem, is actually of little relevance to most of the world. Even if pharmaceutical companies managed to produce enough effective vaccine in time to save some privileged lives in Europe, North America, Japan, and a few other wealthy nations, more than six billion people in developing countries would go unvaccinated. Stockpiles of Tamiflu and other anti-influenza drugs would also do nothing for those six billion, at least 30 percent of whom -- and possibly half -- would likely get infected in such a pandemic.

In the summer of 1918, influenza killed far more soldiers than did bombs, bullets, or mustard gas. By October, some 46 percent of the French army was off the field of battle -- ailing, dying, or caring for flu victims. ...In the event of a modern pandemic, the U.S. Department of Defense, with the lessons of World War I in mind, would undoubtedly insist that U.S. troops in Iraq and Afghanistan be given top access to vaccines and antiflu drugs. About 170,000 U.S. forces are currently stationed in Iraq and Afghanistan, while 200,000 more are permanently based elsewhere overseas. All of them would potentially be in danger: in late March, for example, North Korea conceded it was suffering a large-scale H7N1 outbreak -- taking place within miles of some 41,000 U.S. military forces. It is impossible to predict how such a pandemic influenza would affect U.S. operations in Iraq, Afghanistan, Colombia, or any other place.

Although there is little evidence that isolation measures have ever slowed the spread of influenza -- it is just too contagious -- most governments would likely resort to quarantines in a pandemic crisis.

In 1971, the great American public health leader Alexander Langmuir likened flu forecasting to trying to predict the weather, arguing that "as with hurricanes, pandemics can be identified and their probable course projected so that warnings can be issued. Epidemics, however, are more variable [than hurricanes], and the best that can be done is to estimate probabilities."

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