A couple of years ago, when bird flu was discovered in England, I went on a knowledge expedition, reading everything I could find out about influenza, pandemics, and their causes. What I learned scared me, enough so that I prepared a "bird flu emergency box", with candles, soap, and other emergency rations.
The scary thing about pandemic influenza is its propensity for morbidity among the young and healthy. Before, whenever I'd read about infectious diseases, I'd give myself a mental pat on the back, thinking with my healthy immune system—a product of my healthy diet and the gallons of green tea I drink—I won't be at risk. After all, I hardly ever get sick with the usual cold viruses.
But then I read about the virulent 1918 influenza pandemic, when young, healthy people were the most likely to die—exactly the opposite from what occurs in usual flu epidemics, which are deadly for old people and immune compromised individuals.
The reason this happens is because an excellent immune system is the means by which the virus kills. The body's immune reaction causes the lungs to fill with fluid, and the patient to expire from lack of oxygen. This process of overreaction by the immune system is called a "cytokine storm". Here's a more technical description:
Once infected with a pathogenic influenza, the blood vessels in a patient’s lungs become porous and fibrinogen—a protein involved in blood clotting—leaks into the lungs. The protein clogs the lungs’ alveolar sacs, where gas exchange takes place, and an acute respiratory disease syndrome results. In a desperate effort to save its charge, the immune system recruits such a storm of immune cells that the lungs suffer oedema. In effect, patients drown in their own fluid only days after infection. Patients with the most responsive immune system produce the greatest immune storms. It remains to be seen, however, whether the same mechanism explains the age distribution of the current outbreak.
I've read horrible descriptions of patients dying during the 1918 pandemic, first turning blue, then black, coughing blood, their lung sacs bursting—truly scary. Scary enough to wipe the smug look off my face, as I thought of my healthy young daughters, my own super charged immune system, hopped up on green tea and antioxidents.
We'd be the first to die in a pandemic.
So with the advent of a novel swine flu virus, which has the potential to become a pandemic, I wondered: is it time to panic? Or is this a false alarm? And most importantly, will modern medicine save us?
There are some puzzling aspects of this new virus. First, it's a combination of a bird flu virus and a swine flu, both of which have the ability to infect humans. There is speculation it may have been hatched in a large hog producing plant in Vera Cruz, near a poultry processing plant. That's no surprise, for anyone aware of how the close proximity of industrial farm animals contributes to the likelihood of serious pathogens evolving. (Again, this article explains that very well.)
Its mortality among the young and healthy in Mexico is the most frightening aspect of the current swine flu. Again, not that unexpected, if you've read about the 1918 pandemic, which killed many young men fresh from the trenches of the First World War.
But the oddest thing I've read about this new flu is its lack of morbidity elsewhere. As I write this, early in the afternoon on April 27, there are no reported deaths in any location other than Mexico. That could change, and very likely will, but for now no one has had a serious case outside of Mexico.
What does that mean? It's unlikely due to poor health care in Mexico versus the rest of the world. Mexico City, where most of the deaths occurred, has access to health care, same as any large city, and to treat a serious case of flu all you really need to do is get to a hospital—no fancy medical equipment is needed. Tamiflu, an antiviral drug (NOT a vaccine, as some reporters in yesterday's White House news conference seemed to think) is effective against this flu, so far. But curiously, no one outside of Mexico seems to have had a serious enough case to call for it. Indeed, it's likely few patients with mild flu symptoms would have gone to the doctor if there hadn't been reports of swine flu in Mexico.
Reports suggest that during the 1918 pandemic, an earlier, milder, wave of flu hit, then months later, the pandemic became more virulent. It's possible we're seeing a first wave of mild severity, but that doesn't explain why Mexico has been hit by such a virulent strain.
Has the virus already mutated to a less virulent form? Viruses can't kill their hosts too quickly, or they don't get passed on to other hosts. Their chance to replicate is nipped in the bud when they kill their host. So it's to their benefit to only make a host mildly ill. Perhaps this is a very intelligent virus, that quickly learned to lay off the morbidity. (That's a joke; viruses aren't really intelligent, though the natural selection process makes it seem as if they are.)
The virus seems to be spreading around the globe pretty fast. This morning a case was confirmed in Spain. Canada has several cases, as does New Zealand—all traced to Mexico tourist travelers. But if all it does is make people mildly ill, then it's no worse than the typical seasonal flu.
Unfortunately, that's likely to change, as the acting director of the Center for Disease Control, Dr. Richard Besser, warned yesterday.
When it does, I'll make sure my Pandemic Preparedness Box is up to date. I'll buy new batteries, fill the bathtub with water, buy cough medicine and fever reducers. And I will panic.
But for now, I'm not panicked. Just curious.
Places where I go for information:
Effect Measure
H5N1
Aetiology
Breaking news
And what started it all: The Bird Flu Book.
