Vaccine hesitancy + climate change + natural disasters = zombie apocalypse?
It’s safe to say that all things zombie are now mainstream (any Walking Dead fans here?). What’s not to love about postapocalyptic times where dead people come to life and have no purpose other than to feast on the living? But what do they have to do with vaccine refusals, climate change and natural disasters? I’m glad you asked.
Disclaimer: I don’t think there’s a virus capable of reviving the dead. But if you’re wondering if there are diseases and environmental factors that can promote zombie-like infections in the population at large (which we’ll call a “zombie apocalypse” for this article), then my answer to you is “Hell, yes.”
Did you know there are real-life zombie scientists? Okay, so that may be a stretch, but epidemiologists come pretty close. Epidemiology focuses on where diseases come from (their origin) and how they spread (their distribution). Epidemiologists study singles cases, outbreaks and epidemics, documenting trends for viruses like Ebola, West Nile virus, swine flu (H1N1) and Zika — just a handful of the diseases that have garnered international attention and caused widespread panic in the past decade. Their destructive reach can be attributed to what’s known as the epidemiologic triangle. Researchers often look to this model to understand how diseases spread, and it can be broken down into three distinct parts: agent, host and environment.
1. Agent: A Deadly Disease
Background: To have a zombie apocalypse, we need to have a devastating disease outbreak, right?
Real-world possibility: Ebola virus.
Also known as Ebola Hemorrhagic Fever, symptoms include severe headache, muscle pain, weakness, fatigue, diarrhea, vomiting, abdominal (stomach) pain and unexplained hemorrhage (bleeding or bruising). Sounds zombie-like, right? The Ebola virus is spread through direct contact, meaning that droplets containing the virus from an infected person must come into contact with another person’s mucus membranes, including membranes around the eyes, nose or mouth. Ebola is not believed to be spread via air or water and usually not through food, but infected animals, such as bats or primates, can carry and spread the disease, putting people at risk for the virus if they come in contact with the infected animal, a phenomenon known as spillover effect.
Diseases like Ebola are especially dangerous today. Thanks to globalization and increasing technological advances, we are more connected than ever. Millions of people travel internationally, coming into contact with and potentially carrying dangerous diseases. Ebola symptoms can take days or weeks to develop, leaving a trail of unsuspecting people potentially infected.
2. Host: A Carrier
Background: To have a zombie apocalypse, the disease needs a vessel, or host, to transmit it to a healthy individual.
Real-world possibility: Animals, human-to-human, food-borne.
Germs can spread in a variety of ways, including through direct contact (skin-to-skin), indirect contact (coming into contact with places where germs are present), vector-borne (passed from a vector, like a mosquito or tick) and food-borne (illnesses originating from contaminated food sources).
Diseases that are passed from animals to humans are known as zoonotic diseases and are surprisingly common. This makes sense, because we as a race have domesticated animals to keep as companions, and we utilize them daily in agricultural processes for food sources. According to the Centers for Disease Control (CDC), more than 60% of infectious diseases in people are spread from animals, and 75% of new infectious diseases in people are spread from animals. In fact, the CDC has a whole list of diseases that can be spread from pets to people. Well-known zoonotic viruses include West Nile and Zika, spread by mosquitos, and Lyme disease, spread by ticks. People act as carriers and bring new diseases to foreign countries, risking passing them to individuals and other animals (reverse zoonoses). These animal vectors can then spread this new infection to other animal species and potentially back to humans.
People and animals are not the only carriers of dangerous infections. Food-borne illnesses infect one in six Americans and cause 3,000 deaths annually, which explains strict health code enforcement and bans on foods brought in from foreign countries.
3. Environment: The Perfect Storm
Background: To have a zombie apocalypse the “environment,” epidemiologically speaking, must have factors that make it easier for a disease to spread.
Real-world possibility: Vaccine hesitancy, antibiotic resistance, food storage threats.
In 2005 the World Health Organization sent out a statement about vaccinations: “As the recent Ebola crisis tragically brought to light, engaging with communities and persuading individuals to change their habits and behaviors is a lynchpin of public health success. Addressing vaccine hesitancy is no different.”
Arguably, public health’s crowning achievement in the 20th century was the eradication, elimination and reduction of infectious diseases such as smallpox, polio and measles through immunizations and the subsequent herd immunity (the masses’ immunity protecting the vulnerable groups from infection) achieved by high vaccination rates. In recent years, however, health professionals have seen a rise in vaccine hesitancy. Skepticism toward the efficacy of immunizations has opened the door for these illnesses once thought to be contained to reappear, putting millions of lives at risk. While there is a lack of trust in immunizations, there’s an overreliance on antibiotics. As a result, there’s a rise in antibiotic resistance, meaning that new strains of pneumonia, tuberculosis and gonorrhea bacteria are no longer as susceptible to antibiotics.
Natural disasters created by climate change can exacerbate these efforts to control and prevent disease and, in case you haven’t noticed, we’ve had quite a few across the globe. As infrastructures are taxed and resources are directed toward evacuations and life-saving rescues, sanitation and hygiene suffer. Flooded cities teem with deadly bacteria, and mass shelters become a hotbed of germs, easily transmittable due to large populations living in close quarters and limited hygiene options. In fact, there’s been a report of a Hurricane Harvey first responder contracting flesh-eating bacteria from an insect bite. Even the Global Seed Vault is not immune to environmental adversaries.
The future looks uncertain as our cities flood, our food supplies become less secure, our faith in health professionals falters and science struggles to keep up with ever-evolving infectious diseases. The notion of rapid-spreading, zombie-like illnesses doesn’t seem far off, does it? What more evidence could we need to engage in public health prevention efforts and sustainable living practices? Until then, check out the CDC’s Zombie Preparedness recommendations.