Epi Shack: You've got questions about Avian Flu. I have some answers.

I have had eight people ask me in the past week about Avian Influenza, so I figure I ought to address it. Let me say up front that this is not something I've studied extensively in the six weeks I've been an epidemilet, as Michael calls us epidemiology students. I will do my best to summarize the information as I understand it because I don't want you hearing it from your friends in the girls room, but take this with enough grains of salt to kosher a cow.

Let me skip to the trolls: I do think it is worth being concerned about an influenza pandemic, in part because it is possible to make a big difference by preparing for it. I do not, however, as Rich put it to me, think that it will wipe out our civilization the way lead poisoning did the Roman Empire.

Here is more detail:

What is Avian Influenza? Let me first say what it is not: the Stomach Flu. There is, in fact, no such thing as a Stomach Flu. There are certainly viruses that make you puke, but they are not Influenza. According to one of my professors who is much smarter than I am, most of the times you thought you had the Stomach Flu you actually had food poisoning. Influenza primarily attacks the respiratory system (nose, throat, lungs), and is accompanied by muscle pain and fatigue. It is endemic in the U.S. (and around the world), meaning that one expects to find it just about all the time at relatively constant levels--it is a seasonal disease, meaning infections increase in Winter, but they come back down each summer. People who are otherwise in good health will usually recover from a flu infection in a matter of days, but the very old and the very young are much more vulnerable to the disease, and for them it can be quite serious. The CDC reports that about 36,000 people die from Influenza in the U.S. each year. What's weird is how few people know that.

Like any other infection, once you have had one strain of the flu you are immune to it. The trick is that the Influenza virus mutates rapidly compared to other viruses. Every so often a random change in the virus' genetic material causes it to be copied a little differently. We call it a new strain of the virus when the mutation changes the part of the virus that our immune system is able to recognize without changing the parts that the virus uses to attack our cells and reproduce there. At any given time there are numerous strains of the flu circulating the globe, which is why we are able to get sick with it year after year. We are actually catching entirely new strains each time. When you get a flu vaccine, you are being vaccinated against a combination of strains that Epidemiologists and others predict will be most likely to run amok that year. It is not a guarantee of immunity to all types of flu.

The virus can live in other vertebrate species than humans. The usual suspects are pigs and birds--that's where the Avian part comes in--but one of the news items of recent concern is that strains are being detected in totally new species. Like leopards. Other species can be the source of a strain of virus new to humans. In a typical year, a virus is unlikely to be passed between humans if it is so deadly that it kills its host. Dead people are not as good at spreading viruses as live ones. That usually means that a kind of natural selection keeps milder viruses in circulation over more virulent strains. If, however, a mild virus has been circulating successfully in the bird population and is transferred to a human, it might prove to be far deadlier in humans than it was in birds. This happens every few years, but so far the international health community has managed to cooperate just far enough to contain each outbreak. A high proportion of the people infected with these strains died, but the infections were prevented from spreading to many people who had not gotten the virus directly from the birds.

The next obvious question is: what would happen if an outbreak of Avian flu were not discovered in time to contain it? This is where the worst case scenarios arise. A pandemic is an outbreak of a disease that spreads across the entire globe. AIDS, for instance, is a pandemic. The worst known Influenza Pandemic was in 1918-19. That is the doomsday scenario, except it clearly isn't farfetched since it already happened once.

There are some conditions that obtained in 1918 that won't be around to contribute to the problem if we have an outbreak soon. The most obvious was the First World War. On the one hand it crowded people together in cities, military barracks, trenches, brothels and other situations ideal for spreading a virus. On the other it interfered with the practice of prevention, because the countries involved were so desperate to get soldiers to the front that many people with the power to take preventive public health measures did not do so for fear of jeopardizing the war. For instance, at one point roughly half the soldiers being sent from the US across the atlantic would die of the flu on the ship before reaching Europe, but the Navy made the judgment call that those lives had to be sacrificed. Would that happen again today? I tend to think not, though it depends on what day you ask me.

Another obvious improvement since 1918 is in the quality of medical care and our understanding of the virus. In the early years of the pandemic it was not even known whether the disease was caused by a virus or a bacterium, and there was nothing close to a vaccine available. Furthermore, a great many people died not from the virus itself but from bacterial pneumonia which developed while the immune system was weak. Bacterial pneumonia is now highly treatable for those with access to antibiotics. Thirdly, we have better prevention tactics available. We now know that wearing gauze masks and breathing fresh air are useless, and we have nifty outfits like hazmat teams. That's the good news. The tradeoff is that with the advent of air travel and business connections proliferating between nations (legal and otherwise), the virus has many more opportunities to spread.

So what is to be done?

The most important interventions will be on the national and international level. It currently takes about six months to turn around a new flu vaccine. A lot of people could get sick in that amount of time. A second line of defense are anti-viral medications, and that might buy some time. But we don't currently have the infrastructure to produce a new vaccine on the fly and supply it to the majority of Americans--and forget developing countries. One of my classmates just wrote a paper arguing for stepping up the production of flu vaccines in non-pandemic years, and she let me read it. That's a win-win situation, given that as I have mentioned, 36,000 or so Americans currently die of it annually. It would also put us in a better position to distribute the vaccine in the event of a pandemic. Another important large-scale change would involve investing money in disease surveillance so that we can catch outbreaks quickly. There is some legislation to that effect going down soon thanks to Barack Obama and friends. But a lot of the underlying problems are tough to solve. The global nature of the disease means that no one country or small collection of countries can address prevention or containment alone. How can you insure cooperation between the countries where Influenza is most likely to jump from birds to humans (China, for instance) and the countries with the best resources to fight the disease (guess who that would be, and don't say Honduras)?

I'm in the process of investigating what Berkeley's pandemic preparedness plan is; I'm assuming they have one, but if not maybe I'll come up with one. If you're concerned, one thing you can do besides writing to your congressman etc., is to find out what kind of planning your company or school has in place. Couldn't hurt to ask.

I hope that was helpful. Feel free to post questions or requests for clarification. Please be polite.