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(Don’t) Fear the Reaper

Jarrod Johnson

Posted on Aug 31st, 2016

Imagine you are on an airplane right now. A flight attendant announces over the intercom amidst the whir of your plane’s engines as you taxi into the gate. “Upon arrival we will be boarded by a health and safety team dressed in hazmat suits.”

You quickly exchange worried looks with the other passengers. The voice comes on again, “Please do not be alarmed, but authorities are requesting those of us on this flight be immediately placed into quarantine for the next two weeks, as we have reason to believe that one or more of you are contagious.”

What on earth happened? Globalization has extended the reach of an infectious disease. That’s what happened.

As our population increases, this scenario, or something similar to it, is a reality that we might be forced to confront. People are routinely traveling to all corners of the globe for business or pleasure, and it’s a big world out there, with lots of bugs. Thus, we have come face-to-face with the prospect that—at any moment—a disease outbreak is possible.

How worried about this should we really be?

If the media is our indicator, the answer is to raise the alarm. Today, it’s Zika. Two years ago, it was Ebola. We hear warnings of new strains of influenza and frustratingly watch pockets of unvaccinated people spreading cases of measles in California and elsewhere.

These may be the “outbreaks of the moment,” but some of these ‘bugs’ (a catch-all term that we can use for viruses, bacteria, and parasites) are scarier than others. Since we cannot take our safety for granted, when we hear the next ominous news report, or hear a flight attendant announce our impending quarantine, there are two simple things we can do to make sure we’re not overwhelmed with fear:

The first thing to do is to stay informed. We can’t expect to have all our questions answered when we first hear about an outbreak, but having a basic understanding of the disease and assessing our likelihood of exposure can help us react with a level head rather than behave irrationally. The Centers for Disease Control and Prevention offers an up-to-date outbreak tracker and provides suggestions for travelers taking trips abroad

"Our opportunity to beat the worst of these diseases runs in direct correlation with well-funded research and effective science policy."

But the emergence of a new pathogen does more than simply influence travel plans to distant lands. Like a thief in the night, sooner or later an infectious disease will sneak into our backyards and meet us on our own turf.

Just this summer, the first local transmission of Zika virus was documented in the Wynwood neighborhood of Miami, Florida. The Miami Herald has plotted the rise of Zika cases across the state, highlighting the distressing rate at which the spread of the virus is expanding. Experts in the field, such as Dr. Anthony Fauci, have kept a close eye on the outbreak and have concluded that the likelihood of Zika actually becoming a widespread issue across the United States is relatively small. But the fact remains that even a single case of transmission to a pregnant mother is a tragedy that no one should be forced to endure.

It may be difficult to separate fact from fiction with what is often presented in the news, but the research evidence has become quite clear on Zika virus. Infection is associated with Guillain-Barré syndrome, an autoimmune neurological disorder; and sadly, in expecting mothers Zika is linked with severe birth defects, including microcephaly. Until we are able to either get mosquito populations under control, or develop a vaccine against the virus, this fear will remain very real for many people in warmer climates.

The second thing to keep in mind with current “outbreaks of the moment” like Zika and Ebola is to keep them in perspective.

There are other infectious diseases out there that are having a devastating human impact—and have been for decades, like with HIV, or even for centuries, as with malaria and tuberculosis (TB). Just because the BBC and CNN largely ignore them these days, doesn’t mean their impact is any less heart-breaking.

Let’s go back to our thought experiment on the airplane. In this example, I haven’t told you what the disease is, but to get some idea about how serious the threat is, we need to ask a few questions:

How many people die from this disease every year?

How does it spread?

What is its impact rate? (This may be slightly gruesome to think about, but we must account for expected chance of survival vs. survival with complications vs. death.)

The answer to the first question can give us a sense of scope. Roughly 14 million people die from communicable diseases every year, and most of these deaths occur in low-income countries. Who are the heavy hitters?

  • Tuberculosis (TB): 1.5 million deaths worldwide (2014)
  • HIV/AIDS: 1.1 million deaths worldwide (2015)
  • Malaria: 438,000 deaths worldwide (2015)

By contrast:

  • Influenza and pneumonia: 55,227 deaths in the United States (2014)
  • Ebola: 11,310 deaths in West Africa (2014-2016).
  • Zika: 1 associated death in the United States (as of July 8, 2016)

If you live in a developed nation, your chances of dying from heart disease or stroke are much higher than from any infectious disease, but that does nothing to take away the fear we might have of contracting something fatal.

Let’s consider for a minute how these diseases are transmitted. You’re not very likely to catch HIV on an airplane, unless you’re swapping bodily fluids with other passengers. Ebola, Zika, and malaria are also bloodborne pathogens and they too, don’t pose much of a risk in this scenario. With Zika virus and malaria of course, your risk goes up if you are traveling to and from a location where these diseases are endemic and permit a mosquito to orchestrate the act of transmission.

Perhaps the scariest form of disease transmission is through the air. TB, influenza, anthrax, chickenpox, smallpox, and measles are all examples of airborne infectious agents. If you sit next to someone with active TB on an airplane, there’s a good chance you could catch it, as well. Given that a third of the world’s population is latently infected with TB, and strains of drug-resistant TB are emerging, this disease is particularly terrifying.

Impact rate is something else to weigh. The case fatality rate (or CFR) for HIV depends on whether you have access to antiretroviral drugs, as many people who are infected go on to live long and fulfilling lives, thanks to medicine. If left untreated, more than 80% of HIV-positive people will die within 5 years of contracting the disease. Ebola virus has a relatively high CFR, as more than half of documented cases result in death. On the extreme end of the spectrum are things like Naegleria fowleri, (a brain eating amoeba), prion disease, and untreated rabies, which have CFRs at or close to 100%.

Zika virus has only resulted in one death so far in the United States, but that doesn’t do justice to its potential broader impact. Recent data suggests Zika virus might be able to infect brain cells in adults and lead to long-term neurological damage, so beyond its association with birth defects, we’re only just beginning to learn of how the virus might affect men and women who become infected. Unfortunately, we don’t yet have a good way to track its path of destruction that could be concealed within the complex highways of someone’s nervous system.

Our opportunity to beat the worst of these diseases runs in direct correlation with well-funded research and effective science policy.

The swift reaction against Ebola virus from the government and volunteers from around the world helped to stifle the outbreak in West Africa and prevent it from getting out of control. We dodged a bullet that time, but complacency in the future could be catastrophic.

In February, President Obama promised $1.9 billion to help battle Zika, but since then, Congress has balked and has been unable to push forward a funding package. Clinical trials on a Zika virus vaccine are expected to begin soon, but the current money for the project, which has already drained resources from pre-existing projects as it was transferred from other institutes, is expected to run out by the end of the year.

Regardless of our political persuasions, we should never be afraid to fully commit our efforts to improve global health. At the Center for Infectious Disease Research, we are passionate about making transformative advances that lead to the prevention and treatment of infectious diseases. We don’t want to wait until we or someone we love is on an airplane breathing in drug-resistant TB, or something far more sinister.

In our battle against these bugs, you can help by staying educated, supporting research, and becoming engaged in public discussion on science. Adequately funding basic and biomedical research can have a tremendous positive effect, not only in the fight against infectious disease, but in an extended social context. We encourage each of you reading this to contact your representatives in Congress to express your feelings over their reluctance to fund science.

And, most importantly, please vote this November.

About the Author

Jarrod Johnson is a Senior Scientist in the Aderem lab at the Center for Infectious Disease Research. He is working to understand how innate immune cells detect and respond to pathogens such as HIV. Jarrod uses systems biology tools, genome-wide screens, and targeted genetic perturbations to study signaling networks in human dendritic cells. He earned his Ph.D from UNC - Chapel Hill where he worked under the mentorship of Jude Samulski at the Gene Therapy Center. As a postdoctoral fellow, Jarrod trained with Dan Littman at NYUs Skirball Institute for Biomolecular Medicine. Outside of the lab, Jarrod enjoys making memories with his two kids, eating massive breakfasts, exploring the outdoors, and playing jazz guitar.

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