Sep. 14, 2011 at 6:29 PM ET
The hit movie "Contagion" focuses on a fictional killer outbreak that spreads from bats to humans, but a real-life killer is taking the reverse route.
The Hollywood outbreak is based on a real pathogen, the Nipah virus, which originates in bats and can be passed through pigs to humans. The so-called paramyxovirus has been implicated in more than a dozen outbreaks in South Asia. The filmmakers behind "Contagion" merely turned up the dials on the bug's virulence to produce the plot's pandemic.
The real pandemic is afflicting bats, not humans. Biologists are seeing evidence that humans are behind the spread of Geomyces destructans, a fungus that's linked to the bat-killing disease known as white-nose syndrome. In some areas of the northeastern United States, white-nose syndrome is wiping out 90 to 100 percent of the brown-bat population.
Scientific sleuths have traced the disease to the batty equivalent of "Patient Zero": a cave in upstate New York where bats with white noses were first noticed in 2006. When bats started dying, the connection to the white nose led to a determination that Geomyces destructans was playing a role.
"Scientists in Europe said, 'We have bats that are exhibiting similar symptoms, but we're not having the same problem with mortality,'" said Ann Froschauer, a spokeswoman for the U.S. Fish and Wildlife Service who focuses on white-nose syndrome. "One of the leading hypotheses is that recreational cavers potentially brought the fungus from Europe and carried it here."
The suspicion is that fungal spores survived the trip and took root in the New York cave, where the cold and damp conditions were well-suited for the fungus. The effect on bats in the Northeast was eerily similar to the "Contagion" virus' effect on Hollywood actors.
"Once this fungus made its way into our caves in the U.S., it was the 'perfect storm,'" Froschauer explained. "The environmental conditions were right for the fungus to start growing, and bats here don't have any immunity."
The bats were more vulnerable because they were hit by G. destructans while they were hibernating, when their immune reactions were suppressed. And even if one batch of bats is wiped out, the fungus can remain in the caves, waiting for the next wave of bats to move in and spread the disease.
So far, biologists have found signs of white-nose syndrome in 17 states and four Canadian provinces. An international task force, led by the Fish and Wildlife Service and including representatives from more than 100 agencies and organizations, is trying to figure out what to do about the problem, Froschauer said. Among the potential options: holding bats in captivity over the winter to keep them away from the fungus, closing caves to human visitors, developing antifungal treatments, and even cryopreservation of bat sperm and eggs to allow for in vitro reproduction.
Wouldn't the world be better off without bats? Although you might not know it from their Hollywood image, bats do way more good than harm. No joke: A study published in the April 1 issue of the journal Science pointed out that bats are "voracious predators" of insects that include many crop and forest pests. Without bats, North America's economy would suffer agricultural losses amounting to more than $3.7 billion a year, the researchers said. Some have called them the "unsung heroes of organic farming."
Froschauer sees "Contagion" as an opportunity to do some consciousness-raising about the fate of a species that doesn't usually get much sympathy.
"Historically, they've always gotten a bad rap, and especially at this time of year, when we're often dealing with rabies reports," she told me. "In popular culture, they've always had this negative image."
Ali Khan, an assistant surgeon general who leads the Office of Public Health Preparedness and Response at the Centers for Disease Control and Prevention, agrees that bats are classic bad guys.
"They make the best bogeymen, no doubt about it," he joked. "Better than Freddy Krueger."
Nipah virus and rabies aren't the only pathogens linked to bats, Khan pointed out. Researchers believe that fruit bats are the natural reservoir for the Ebola and Marburg viruses, which cause deadly hemorrhagic fevers in humans. Bats are also thought to be a natural host for viruses similar to the one that causes severe acute respiratory syndrome, or SARS.
But bats aren't the only suspect when it comes to species-jumping diseases. The list also include pigs and birds (implicated in 2009's global outbreak of H1N1 swine flu) as well as monkeys (implicated in the long-running HIV epidemic), mice (linked to hantavirus) and rats (linked to the Black Death in the Middle Ages).
Khan told me that "Contagion" has stirred up a lot of interest among the press and the public in the question, "Could this really happen?"
"Not only 'could this really happen,' but it routinely happens," he answered, "not just to the magnitude seen in the movie — except perhaps during the 1918 flu pandemic or the Black Death."
Like Froschauer, Khan sees "Contagion" as a teachable moment for epidemiologists — and now that he's seen the movie, he gives it a big thumbs-up. "They did as good a job as you could expect for Hollywood," he said.
That shouldn't be surprising when you consider that the film's actors visited the CDC headquarters in Atlanta to chat with Khan and other experts. "When Kate Winslet said, 'This is what an R-naught is,' I thought, 'I taught her that!'" Khan said.
Khan realizes that Hollywood requires villains as well as heroes to tell a good story, but he nevertheless wanted to clear up a couple of things about the way the movie portrayed epidemiologists doing their jobs:
Then Khan had a darker thought. "Maybe that's the future situation, if there are continued CDC [budget] cuts," he said. "There will be no one available to go out and deal with pandemics."
Now that would be a scary movie.
More about 'Contagion,' bats and public health:
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