This past year’s deadlier-than-usual flu season cost the U.S. an estimated $15 billion in lost productivity, as millions of infected workers called out sick. And as the Zika outbreak proved in 2016, there is reason to be worried that we aren’t doing enough to prepare for whatever infectious disease comes at us next.
To that end, scientists are turning to an unlikely ally in hopes of learning how to prevent, or quash, the next global health threat: the lowly amphibian.
In the late 1990s a deadly fungal pathogen ravaged millions of amphibians around the world, leading to catastrophic losses among their populations. But researchers recently found that a few species of frogs in Central America, which were thought to be extinct, have rebounded and, in some cases, developed even stronger defenses against the infection.
The study, published last month in the journal Science, looked at how the froggy fungal disease, called chytridiomycosis, went from epidemic levels, when an infectious disease introduces itself quickly and affects large populations, to an endemic, or the point at which the disease becomes commonplace. The fungus is still around and as deadly as ever, suggesting that some frogs have evolved to create resistance to the disease.
“If you’ve ever held a frog or toad, people have that experience of it being a slimy animal. That’s because they have these secretions as a defense mechanism,” says biologist Jamie Voyles, an assistant professor at the University of Nevada, Reno, who led the multiyear study. “Amphibian skin is actually a very complex physiological organ, so in addition to water absorption, there are also these secretions that are helpful to the immune system and are really good at inhibiting pathogens.”
Perhaps the most interesting takeaway from the study, though, can be gleaned by examining what happens to populations — and the disease itself — after an epidemic, which can inform how we to respond to human-spread diseases in the future.
“Historically, we’ve viewed infectious diseases as being able to shift over time, but we haven’t fully clarified how that works,” says Voyles. “Think of the more notorious cases of influenza, or similar kinds of outbreaks, where there is a large panic and high mutation rate, and where we know that the virus is changing all the time from one strain to the next.”
An example of this disconnect between what happens during an outbreak and what happens afterward is the 2015 Ebola pandemic, which sparked widespread media hysteria and killed more than 11,000 people.
“There is a drop-off in attention paid to host populations after an outbreak,” she says. “We tend to do a lot of hand-waving when an epidemic is going on, but [we don’t much] hear about follow-up in [terms of] understanding the disease after an outbreak.”
By continuing to examine how outbreaks affect wildlife after the fact, we might be in a better position to contain epidemics among humans in the future, says Voyles.
“If we understand the mechanistic underpinnings of how outbreaks happen, then we can apply those lessons to how we respond to other emerging infectious diseases,” she says.
The threat of a devastating global pandemic is increasingly worrisome for public health experts. They point to the lack of preparedness among some nations, even as others, such as the U.S. and China, have established rapid-response teams to swiftly deal with an emergency.
Or as Jimmy Whitworth, a professor at the London School of Hygiene & Tropical Medicine put it, “We’re only as secure in the world as the weakest country.”
And as the worldwide population grows and people pack themselves into ever-denser urban areas, as well as expand to regions previously inhabited only by wildlife, the opportunity for the spread of catastrophic diseases is only increasing.
More worrisome still: As the global stakes rise, funding in the U.S. is being cut.
The Trump administration’s fiscal plan for 2018 slashes millions of dollars from the Centers for Disease Control’s budget, which has led the agency to roll back its efforts in global-disease prevention by 80 percent.
“[Outbreaks and infectious diseases] are not problems that are going away,” Voyles says. “It’s an increasingly connected world, and what that means is that we’re going to be moving more pathogens all around the globe.”
The current situation, much like amphibians themselves, is, in a word, slippery, where preparedness for pandemics is taking a backseat to other economic priorities. Our best hope, then, might just lie with the frogs and what they can teach us about winning the war on global disease.