As you may have learned in a previous post in this space, I have recently been accepted to a masters program in public health. Part of this interest came from numerous discussions with my buddy, who is currently getting his masters in epidemiology ("the science behind public health") at the University of MN. With many stories out there these days confirming that flu pandemic is a matter of when, not if, I thought it'd be good to get the take of a burgeoning expert in the field. Enjoy:
So I was sitting in the lounge of the hotel and convention center one evening sharing a drink with about a half dozen of my colleagues. This was after a long day of lectures and breakout sessions about avian flu and business preparedness. The cocktail server, an absolutely stunning blonde in a black skirt with a high slit that left little to the imagination, tried to make friendly conversation:
“What conference are you all with?”
“We’re here for the pandemic influenza summit.”
“Pandas???” she asked, excitedly. (Huh? Honestly? Pandas?! What the fuck would we be attending a panda conference for? Do they even have such a thing?)
“Uh, no. Pan-dem-ic. Pandemic flu. You know, bird flu?”
“I guess I don’t know what that is…”
That’s OK, I thought. I was easier on her than my peers. She was attractive enough that she could afford to be completely oblivious to even the most basic current events, I would imagine. For the rest of us, those that aren’t so genetically fortunate, pandemic influenza is definitely something worth knowing about and understanding. So at Josh’s request, I will attempt to give some insight into the topic.
About 16 “college students” were invited to attend our professor’s conference in Orlando at the beginning of this week to hear from industry experts and leaders of business. They were to discuss pandemic preparedness (In case you don’t know, “pandemic” refers to an epidemic that spreads throughout the globe). I use the term “college students” loosely here because, although technically correct, graduate students seem to display none of the propensity toward irresponsible alcohol consumption and debauchery that their more junior colleagues participate in. An entire class getting an all expense paid trip to Florida in the dead of winter and no inappropriate stories to relate? Afraid so. In lieu of more hedonistic distractions, I had to pay attention. Here’s what I learned:
H5N1 refers to the makeup of hemagglutinin (5) and neuraminidase (1) on the surface of the virus. There’s a multitude of different subtypes of each. I don’t understand what that means either, so don’t worry. The important thing to know is that this is a novel strain, of which there is no preexisting immunity in our population. The H3N2 strain, of which we get yearly flu vaccines for (And if you don’t, you ought to), was the last pandemic strain. This particular virus caused a pandemic back in 1968. It was a bit milder, and unless you kept tabs on hospital admissions, it is likely that you might not have noticed it in day-to-day life. Killed a lot of people, but definitely not as serious as say, the 1918 pandemic. So the 1968 H3N2 strain is still the dominant flu virus, and it changes a bit each year to necessitate a new vaccine. Due to preexisting exposure to H3N2, it’s generally not something to freak out about unless you are super old or super young. If H5N1 is the next pandemic strain, then it will also eventually become the yearly flu virus that we get vaccinated for. By then, we will have been exposed to it and it won’t be as big a deal. Just a “normal” flu, so to speak (Although keep in mind that “normal” flu still kills around 36,000 people a year in this country). The lack of resistance to H5N1 at present is what will make it lethal. What is interesting about this virus as well, is that the greatest mortality takes place in the segment of the population possessing the healthiest immune systems. Young adults will be disproportionately impacted. Because infection gives such a tremendous shock to the immune system, a phenomenon known as a “cytokine storm” occurs in the body. This is essentially a crazy immune response that destroys tissues in the body while trying to fight the invading virus. The healthier your immune response, the more damaging it can be. So higher mortality rates will be in effect for those, say 18-45.
H5N1 is the strain being watched right now as the likeliest candidate for a pandemic. At present, it is strictly an avian strain. It’s transmissible in wild and domestic birds (And even felines occasionally, as was evidenced when they fed raw chickens infected with H5N1 to tigers in a Chinese zoo), but is reluctant to infect humans, except in rare circumstances. There have been roughly 270 human cases with over half of them ending in death. So it’s a particularly nasty virus, and death is rather unpleasant. Bleeding from the nose and mouth, as well as the eyes and ears, in some circumstances. Some birds, such as mallards, have adapted to this particular pathogen and can carry and transmit it with no detrimental effects to themselves. Other species, such as cranes, readily die when infected with H5N1. This makes cranes an excellent indicator species for the presence of H5N1. Since it is an avian only strain at present, as I mentioned, it has a very limited ability for transmission among humans. But viruses are constantly mutating and changing. Asia has been described as the “genetic roulette table” for this virus’s potential mutation toward infecting humans readily. Their tremendous poultry industry assures close contact with birds that will be carriers of the virus. So while once in a while, the virus will infect humans, it isn’t yet designed to spread readily throughout the human population. But with enough mutations and chances, it is a definite possibility.
“Reassortment” is the most likely scenario. Swine are unique in that they are susceptible to both avian and human strains of influenza. A pig cell infected simultaneously with a human and avian strain of the flu may combine the two into some kind of hybrid that more readily infects humans. The good news about this is that since the virus is partially from a human strain of the flu, we have some familiarity with it and the mortality rate will drop. Not that it wouldn’t still be a terrible situation, but it is not the worst of all possible outcomes.
On the other hand, it may go through “adaptive mutation.” In this scenario, the avian strain mutates in a way that will allow it to readily infect humans and spread from human to human. It would remain a completely foreign, avian strain of virus. It is a matter of finding the right “key” to invade our cells and transmit itself readily person-to-person. From a 2006 WHO report:
Should the virus improve its transmissibility by acquiring, through a reassortment event, internal human genes, then the lethality of the virus would most likely be reduced. However, should the virus improve its transmissibility through adaptation as a wholly avian virus, then the present high lethality could be maintained during a pandemic.
Holy! Fuck! The WHO conceded that there is a possibility that a pandemic strain could have a + 50% case-fatality rate? That is some serious shit, right there. To put it in perspective, the 1918 pandemic had a 1-2% case fatality rate and still managed to kill as many as 100 million people throughout the globe.
Another important thing to keep in mind is that pandemics do happen. It’s not a matter of “if,” but rather “when.” Just like earthquakes, volcanic eruptions and tsunamis, pandemics are naturally occurring events. And if H5N1 is the culprit this time around, it has the potential to be very dire. It’s not very often that we have some prior knowledge about a crisis situation such as this one. To do nothing to prepare for it would be foolish. However, it isn’t guaranteed to happen tomorrow. No one can predict when or where it will develop. Asia is the most likely region for it’s development, but we can’t be certain. Just because the story of pandemic influenza has fallen out of favor in recent months in the media doesn’t mean we are in the clear by any means. Public health folks are still watching this very closely and taking it quite seriously.
The summit I attended focused on business preparedness, as this will be the key to a functioning society in the event of a pandemic. The public health role will, in actuality, be rather limited. The role of the federal government will also be quite limited. In an event such as the tsunami or hurricane Katrina, only one specific area or region was affected. The resources from the rest of the country/rest of the world were available to those who were experiencing the crisis. In a pandemic, everyone will be going through the same situation at roughly the same time. So you better hope your local area is prepared. Businesses will need to have a plan in place to deal with absenteeism rates of up to about 40%. The “just-in-time” global economy will make it difficult to keep even the most basic supplies such as drugs, water purification, and food production in proper running order. If the supply is interrupted for more than a day or two, we will be in serious trouble. Hospitals, due to the constant attempt to cut health care costs, do not have the excess beds to accommodate even a small increase in inpatient treatment. Pandemic influenza would overwhelm their capacity, as happened in the 1918 example. Combine this with interrupted supply lines for even the most basic medical supplies such as insulin, antibiotics and oxygen, and our standard of medical care could resemble that from the early 1900’s as well. So it’s of utmost importance to keep our supply lines as functional as possible.
The virus will occur in waves. A vaccine, in all probability, will not be available for the first wave of the pandemic. The U.S. goal is to have enough vaccine for the country’s population 6 months after the first wave begins. Canada has a goal of 1 month for their population. Those crafty fucking Canucks! They think they are so smart! We oughtta be able to do that! Anyways, so don’t plan for a magic cure initially. And with the rapidly mutating virus, it isn’t a guarantee that drugs, such as Tami-flu, will be effective either.
So, yeah. That’s my rant. Not sure of copyright laws and intellectual property on blogs, but my information comes from lectures by Michael Osterholm, who I describe as the “Yoda” of infectious disease, from various speakers at the Pandemic Preparedness Summit, and from John Barry’s book “The Great Influenza.” For more on pandemic flu, I highly recommend it, even though he comes across as rather pompous in person, having had the opportunity to meet him at the summit. But he presents the material in an accessible and, for the most part, entertaining way. Although it is primarily about the 1918 pandemic, the text is rich with information on all sorts of neat stuff.
Sorry for how verbose I became. But I am just bonkers about this avian influenza shit! Now go wash your hands, and for god’s sake, cover your mouth when you cough!
