Swine Flu, now officially known as H1N1

I’ve been following the swine flu scare quite closely, having long been interested in infectious diseases that have spread widely, causing the great pandemics of history.  One of the reasons I went back to grad school recently to study biology was because of my concern over the devastation wrought by HIV-AIDS.  I wanted to know more about these deadly agents that can cause so much misery and death.

Influenza subtype A H1N1 is frightening because, according to the CDC, it represents a novel mix of elements from human, bird, and pig influenza virus genomes.  When human immune systems are exposed to a new infectious agent, we have no existing antibodies to attack and neutralize it.  Thus, when confronted with such a pathogen, we’re more likely to get sick than if we had already had full or partial immunity.

Immunology is a highly complex discipline, however, and viruses are tricksy creatures.  From what I’ve been able to understand about the current situation, we’re still in the learning phase when it comes to A H1N1.  We just don’t know enough about it yet.  And even if we did, viruses evolve rapidly.  They lack some of the sophisticated error checkers that do quality control on replication in more complex eukaryotic cells (i.e., the kind of cells we humans are made of).  Thus viruses mutate quickly, which can result in increased or decreased lethality, transmission, and resistance to antiviral medications like Tamiflu.

Flu bugs tend to spread less in the warmer months, which is why our typical flu seasons start in the fall and end in the spring.  In the northern hemisphere, summer is approaching, which should lead to a drop-off of A H1N1 cases (although countries in the southern hemisphere might suffer an increase).  But the World Health Organization and the CDC are concerned that a summer drop-off might be the lull before the storm.  During the post-World War I influenza pandemic of 1918-19, which is believed to have killed 20-40 million people, the flu started in the spring, died down during the summer, then came back roaring the following fall/winter, killing far more efficiently than the usual flu virus.

From what I can make out from reading and digesting a lot of the current information that’s out there, the current H1N1 bug is nowhere near as scary as the 1918 version.  It’s not as lethal, it’s probably less contagious, and it’s apparently not causing death by cytokine storm (where you’re effectively destroyed by your own hyperactive immune reaction).  But viruses being somewhat unpredictable, this could change…which is why we’re being warned to stay alert, cover our mouths when we cough or sneeze, stay home from school/work if we’re sick, and wash our hands frequently with soap and warm/hot water.

This afternoon’s latest alert from the World Health Organization begins like this: “4 May 2009 — As of 18:00 GMT, 4 May 2009, 21 countries have officially reported 1085 cases of influenza A (H1N1) infection. Mexico has reported 590 laboratory confirmed human cases of infection, including 25 deaths. The United States has reported 286 laboratory confirmed human cases, including one death.”

Map of H1N1 cases