Kids are back in school sharing their germs, flu season has begun, millions of people have just returned home from the annual pilgrimage to Mecca, and infectious disease experts are wondering if last year's avian influenza will re-emerge in China this fall. Are we prepared for a disease outbreak?
The explosion of zombies in popular culture and the similarities between zombie events and disease spread led me to wonder: What could zombies tell us about outbreaks of scary new diseases? With Halloween quickly approaching, a brave epidemiologist colleague, Dr. Damien O. Joly from Metabiota, and I decided to interview a zombie to gain insights for protecting ourselves from epidemics.
Here's what we learned during our meeting:
WBK/DOJ: As a zombie, what's really most important to keep the party going, so to speak?
Z: I try to stay focused on how many other humans I can turn into a zombie before I get destroyed. We all need to infect at least one or more people, otherwise the whole event just fizzles out before sunrise. Epidemiologists call this number "Ro," or the "basic reproductive number." It's not a particularly sexy term, but then again, none of us would be here without it. If you can reduce transmission between people, then you get rid of zombies (and infectious diseases).
WBK/DOJ: Once you get a person infected, how long does it take for them to become a zombie or begin infecting other people?
Z: Ahh, that's a critical point, and some of us take different approaches. Disease experts call it the "latency period." Some zombies are more stealthy and take a long time before they are contagious or begin showing signs, like in the Walking Dead. Others, like common colds or zombies in World War Z, take their toll pretty quickly. When you're quick, you can do a lot of damage in short order, but you also make yourself more obvious. The more subtle zombies, just like HIV/AIDs, can spread around the world and get well established before being noticed.
WBK/DOJ: Are you guys everywhere, or should people avoid some places if they really don't like zombies?
Z: Frankly, there do appear to be hotspots for zombies, just like the hotspots for emerging diseases identified by EcoHealth Alliance. Based on the genre, zombie apocalypses seem to disproportionately start in the United States. But that observation could be biased by where more movies are made and how many people use social media like Twitter. You medical folks seem to have similar biases with disease reports due to uneven access to health care, awareness, reporting systems, etc. On the other hand, certain conditions for outbreaks such as population density, human behavior and other risk factors are more likely to occur in certain parts of the world, and those disease events are actually predictable.
WBK/DOJ: Any tips you can give us to avoid a zombie disaster?
Z: Well, now you are getting serious. Like novel emerging diseases and pandemics (e.g., Ebola, SARS, etc.) a zombie apocalypse is universally associated with breakdown of infrastructure and general society. This is why the US Centers for Disease Control has developed a (tongue-in-cheek) zombie preparedness guide. My mother, who was not a zombie, always said "Wash your hands, cook your food and don't stay out late." I wish I had listened to her.
WBK/DOJ: A zombie apocalypse would be pretty devastating. Can't humans and zombies just get along?
>Z: That's a very good question. Philip Munz and colleagues at Carleton University and the University of Ottawa asked that exact question and used Susceptible-Infected-Recovered (SIR) models to predict the outcome of a zombie outbreak. SIR models are mathematical simulations used to estimate how quickly a disease would spread, how much vaccination is required to stop it, and other aspects of an outbreak. The models showed that the only way to prevent a zombie take-over was through multiple attacks on us very early in the apocalypse... all other scenarios ended with extinction of humans. Sorry.
WBK/DOJ: Okay, that qualifies as scary. How do we prevent this from happening or allowing zombie safe havens as discussed by the Canadian Parliament? What's the solution?
Z: I shouldn't be telling you this, but probably the best way to head off a zombie outbreak is to invest in efforts to detect the outbreak at its earliest stages, or even find the cause and prevent it from entering the human population as the US Agency for International Development is working on. Like other outbreaks that have had devastating effects on humans, it is cheaper and more effective to detect and stop an outbreak before it really gets going.
WBK/DOJ: Well, thanks for your insights from beyond the grave, we do hope you have a very Happy Halloween -- preferably not in either of our neighborhoods.