What is the Swine Flu?

Depending on which news outlets you read, the swine flu might be The Big One, the pandemic that brings civilization down to its knees. It has proven to be dangerous in Mexico, and much less so in the United States, and has been sort of a warm up (or wake up call) for all kinds of CDC actions.

In reality, the swine flu isn’t that much different from the seasonal flu that strikes every winter in the US. While the initial reports highlighted a high death toll with a low number of reported cases (indicating that this might be a very dangerous virus, indeed), there was some initial confusion about the degree that it had spread, and how many reported cases there were. In large part this is because Mexico has a much less robust disease reporting infrastructure than the United States does, and it’s not certain how widespread the disease really was.

The Swine Flu (also known as the 2009 H1N1 influenza virus) is an avian flu that migrated over to pigs; it looks, from tracking genetic markers, that it was originally an avian flu that moved to pigs in Asia, moved back to birds, and then came to Mexico where it moved to pigs again, and then became transmissible to humans.

The flu virus requires a living host, and likes to live in the mucosal cells of the sinus cavities and lungs; the vast majority of flu viruses belong to birds; a small percentage can make the transmission leap from birds to pigs, and from pigs, gather up the RNA strands needed to infect humans. A large part of the reason for past flu pandemics is because in parts of the world, you get humans, pigs and ducks or chickens or geese all living in the same house or in close proximity.

The flu is not affected by antibiotics, though it leaves the body open for pneumonia, which can be treated with them. The best defense against the swine flu is the same defense you’d use against the seasonal variety: Wash your hands, avoid close contact with large crowds of people, and if you must go in an enclosed space, consider a face mask. Of these defensive techniques, by far and away the most important of them is washing your hands. The flu is transmitted by physical transmission of mucosal fluid. The usual transmission mechanism is someone blows their nose, and touches something that someone else handles a few minutes later; that person then touches their hand to their lips or nose and gets sick.

Very few flu viruses are truly airborne pathogens; the primary benefit of wearing a face mask isn’t to keep you from virus particles in the air, it’s to keep you from inadvertently touching your nose or mouth. The flu virus also has a short ‘shelf life’, it only lasts for 20 to 30 minutes outside of a human host.

In short, the swine flu of 2009, while a good test of our disease control systems, isn’t that much different from any other flu. While touted as a potential pandemic, so far, it’s proven to be no more dangerous than any other flu virus, and summer will probably see it vanish (the flu prefers cool, dry air as a transmission medium). Even so, the CDC is already working on making sure it’s part of the cocktail of dead viruses used for preparing the fall’s influenza vaccines, just to be on the safe side.