Zombie Virus


Title: New, Fast-Evolving Rabies Virus Found -- And Spreading
Date: May 4, 2009
Source: National Geographic

Abstract: Evolving faster than any other new rabies virus on record, a northern-Arizona rabies strain has mutated to become contagious among skunks and now foxes, experts believe.

The strain looks to be spreading fast, commanding attention from disease researchers across the United States (U.S. map).

It's not so unusual for rabid animals to attack people on hiking trails and in driveways, or even in a bar—as happened March 27, when an addled bobcat chased pool players around the billiards table at the Chaparral in Cottonwood.

Nor is it odd that rabid skunks and foxes are testing positive for a contagious rabies strain commonly associated with big brown bats.

What is unusual is that the strain appears to have mutated so that foxes and skunks are now able to pass the virus on to their kin—not just through biting and scratching but through simple socializing, as humans might spread a flu.

Usually the secondary species—in this case, a skunk or fox bitten by a bat—is a dead-end host. The infected animal may become disoriented and even die but is usually unable to spread the virus, except through violent attacks.

Skunks have already been proven to be passively transmitting the strain to each other, as documented in a 2006 study in the journalEmerging Infectious Diseases.

Genetic studies suggest foxes are also spreading the new strain to each other, though the results have not yet been peer reviewed.

Unprecedented Evolution
When a skunk in Flagstaff, Arizona, died of rabies in 2001, wildlife specialists thought it was a "freak accident"—due to a one-off, run-of-the-mill bat bite—said Barbara Worgess, director of the Coconino County Health Department.

Lab tests later showed that the virus had adapted to the skunk physiology and become contagious within the species.

"It shouldn't have been able to pass from skunk to skunk," Worgess said.

Rabies has continued to crop up in skunks for eight years now, despite periodic vaccination campaigns. And so far this year, county officials have documented 14 rabid foxes in the Flagstaff area.

Now laboratory studies at the U.S. Centers for Disease Control and Prevention (CDC) in Atlanta appear to confirm that the fox and skunk rabies viruses are mutated forms of the bat strain.

"We can see degrees of relatedness and patterns in their genetic codes," said Charles Rupprecht, chief of the rabies program for the CDC.

This sort of rapid evolution is exactly what worries public health officials when it comes to all manner of viruses. Virologists haven't seen such fast adaptation to a new species in rabies before.

"That's why Flagstaff is such an interesting story worldwide," said David Bergman, the U.S. Department of Agriculture's state director for Arizona.

"We're watching evolution in action on the ground."

Could Rabies Become Contagious in Humans?
The Arizona rabies situation is risky, because the infected species live so close to people.

Flagstaff's sprawl in recent decades has created a perfect opportunity for rabies to mutate into species-hopping forms, the CDC's Rupprecht said.

New-home construction, often in wooded areas, has actually increased habitat and food sources for bats, skunks, and foxes. Skunks live under houses, for example, and as diggers, make themselves at home on golf courses. Bats, meanwhile, are adept at living in attics and under loose shingles.

As more rabies-susceptible animals congregate in the region, more infections can take place. And each infection is an opportunity for the virus to mutate into a more virulent form—literally upping the odds of a new strain developing.

"That's a pattern that we see all over the United States," Rupprecht said. Similar suburban development in the eastern U.S. in the late 1970s, he noted, led to the spread of raccoon rabies from the Canadian border to the Deep South.

The risk of such a virulent strain jumping to people "should be a major concern," said Hinh Ly, a molecular virologist at the Emory University School of Medicine in Atlanta, who is not involved in studies of the Arizona outbreak.

But no one is expecting the rabies strain to become a contagious, swine flu-like epidemic among humans.

Flu viruses, for one thing, tend to infect people fast, so "vaccination after exposure would be too late to prevent infection," said Elisabeth Lawaczeck, the Arizona Department of Health Services' public health veterinarian.

Rabies takes its time before going from incubation to infection, so post-exposure rabies vaccinations tend to be effective at stopping the virus. If untreated, though, rabies, which attacks the central nervous system, is often fatal in humans.

What Next?
Rabies cases among animals are expected to increase as the spring and summer mating seasons bring potential pairs and rivals together. (Related: 
"Bat Rabies Threat Rises With Summer Temperatures.")

Already, Flagstaff has declared a 90-day pet quarantine—all dogs on leashes and all cats indoors—which began in April.

A wildlife vaccination plan could stem the virus's spread. Local and state officials enacted vaccination programs in northern Arizona in 2001 and 2005 but discontinued each effort after two years without rabies reports—the World Health Organization's standard for declaring an area rabies-free.

Now state vaccination funds have been reallocated, the USDA's Bergman said, and emergency funds are increasingly rare due to the recession.

Adding to the worries, Lawaczeck, the Arizona veterinary official, said she and other public heath officials were "very unsettled" when the first rabid fox reports came in from Flagstaff this year—and not just because of the evolutionary implications for rabies.

"This means a much wider spread of rabies," she said, "because [foxes] travel so much farther" (National Geographic, 2009)

Title: "Zombie Virus" Possible Via Rabies-Flu Hybrid?
Date: October 27, 2010
Source: 
National Geographic

Abstract: In the zombie flicks 
28 Days Later and I Am Legend, an unstoppable viral plague sweeps across humanity, transforming people into mindless monsters with cannibalistic tendencies.

Though dead humans can't come back to life, certain viruses can induce such aggressive, zombie-like behavior, scientists say in the new National Geographic Channel documentaryThe Truth Behind Zombies, premiering Saturday at 10 p.m. ET/PT. (National Geographic News is part of the National Geographic Society, which part-owns the National Geographic Channel.)

For instance, rabies—a viral disease that infects the central nervous system—can drive people to be violently mad, according to Samita Andreansky, a virologist at the University of Miami's Miller School of Medicine in Florida who also appears in the documentary.

Combine rabies with the ability of a flu virus to spread quickly through the air, and you might have the makings of a zombie apocalypse.

Rabies Virus Mutation Possible?
Unlike movie zombies, which become reanimated almost immediately after infection, the first signs a human has rabies—such as anxiety, confusion, hallucinations, and paralysis—don't typically appear for ten days to a year, as the virus incubates inside the body.

Once rabies sets in, though, it's fatal within a week if left untreated.

If the genetic code of the rabies virus experienced enough changes, or mutations, its incubation time could be reduced dramatically, scientists say.

Many viruses have naturally high mutation rates and constantly change as a means of evading or bypassing the defenses of their hosts.

There are various ways viral mutations can occur, for example through copying mistakes during gene replication or damage from ultraviolet light.

(Related: "New, Fast-Evolving Rabies Virus Found—and Spreading.")

"If a rabies virus can mutate fast enough, it could cause infection within an hour or a few hours. That's entirely plausible," Andreansky said.

Airborne Rabies Would Create "Rage Virus"
But for the rabies virus to trigger a zombie pandemic like in the movies, it would also have to be much more contagious.

Humans typically catch rabies after being bitten by an infected animal, usually a dog—and the infection usually stops there.

Thanks to pet vaccinations, people rarely contract rabies in the United States today, and even fewer people die from the disease. For example, in 2008 only two cases of human rabies infection were reported to the U.S. Centers for Disease Control and Prevention.

(See pictures of infectious animals in National Geographic magazine.)

A faster mode of transmission would be through the air, which is how the influenza virus spreads.

"All rabies has to do is go airborne, and you have the rage virus" like in 28 Days Later, Max Mogk, head of the Zombie Research Society, says in the documentary. The international nonprofit is devoted to "raising the level of zombie scholarship in the Arts and Sciences," according to their website.

To be transmitted by air, rabies would have to "borrow" traits from another virus, such as influenza.

Different forms, or strains, of the same virus can swap pieces of genetic code through processes called reassortment or recombination, said Elankumaran Subbiah, a virologist at Virginia Tech who was not involved in the documentary.

But unrelated viruses simply do not hybridize in nature, Subbiah told National Geographic News.

Likewise, it's scientifically unheard of for two radically different viruses such as rabies and influenza to borrow traits, he said.

"They're too different. They cannot share genetic information. Viruses assemble only parts that belong to them, and they don't mix and match from different families."

Engineered Zombie Virus Possible?
It's theoretically possible—though extremely difficult—to create a hybrid rabies-influenza virus using modern genetic-engineering techniques, the University of Miami's Andreansky said.

"Sure, I could imagine a scenario where you mix rabies with a flu virus to get airborne transmission, a measles virus to get personality changes, the encephalitis virus to cook your brain with fever"—and thus increase aggression even further—"and throw in the ebola virus to cause you to bleed from your guts. Combine all these things, and you'll [get] something like a zombie virus," she said.

"But [nature] doesn't allow all of these things to happen at the same time. ... You'd most likely get a dead virus" (National Geographic, 2010)

Title: Fly Parasite Turns Honey Bees Into “Zombies” 
Date: January 5, 2012
Source: 
Discovery 

Abstract: American scientists have discovered that a fly parasite can turn honey bees into confused zombies before killing them, in an advance that could offer new clues to why bee colonies are collapsing.

So far, the parasite has only been detected in honey bees in California and South Dakota, American researchers reported in the open access science journal PLoS ONE this week.

But if it turns out to be an emerging parasite, that "underlines the danger that could threaten honey bee colonies throughout North America," said the study led by San Francisco State University professor of biology John Hafernik.

Hafernik made the discovery by accident, when he foraged some bees from outside a light fixture at the university to feed to a praying mantis he'd brought back from a field trip.

"But being an absent-minded professor, I left them in a vial on my desk and forgot about them. Then the next time I looked at the vial, there were all these fly pupae surrounding the bees," he said.

Soon, the bees began to die, but not in the usual way by sitting still and curling up. These bees kept trying to move their legs and get around, but they were too weak, said lead author Andrew Core, a graduate student in Hafernik's lab.

"They kept stretching them out and then falling over," said Core. "It really painted a picture of something like a zombie."

Further study showed that bees that left their hives at night were most likely to become infected with the fly parasite, identified as Apocephalus borealis.

Once bees were parasitized by the fly, they would abandon their hives and congregate near lights, a very unusual behavior for bees.

"When we observed the bees for some time -- the ones that were alive -- we found that they walked around in circles, often with no sense of direction," said Core.

The parasite lays its eggs in the bee's abdomen. About a week after the bee dies, the fly larvae push their way into the world, often exiting from between the bee's head and mid-section.

The research, which has also confirmed that the same flies have been parasitizing bumblebees, won local excellence awards when it was first presented last year.

Next, the team hopes to find out more about where the parasitization is taking place, and whether the "zombie bees" leave the colony of their own accord or if their disease is sensed by comrades who then push them out.

Researchers plan to use tiny radio tags and video monitoring to find clues to the mystery.

"We don't know the best way to stop parasitization, because one of the big things we're missing is where the flies are parasitizing the bees," Hafernik said.

"We assume it's while the bees are out foraging, because we don't see the flies hanging around the bee hives. But it's still a bit of a black hole in terms of where it's actually happening."

Experts have theorized that the huge die-off of bees worldwide since 2006, a major threat to crops that depend on the honey-making insects for pollination, is not due to any one single factor.

Parasites, viral and bacterial infections, pesticides, and poor nutrition resulting from the impact of human activities on the environment have all played a role in the decline.

The mysterious decimation of bee populations in the United States, Europe, Japan and elsewhere in recent years threatens agricultural production worth tens of billions of dollars (Discovery, 2012)

Title: Parasitic Fly Creates "Zombie Bees" – A New Factor Explaining Colony Collapse Disorder
Date: February 16, 2012
Source: 
Natural News

Abstract: Researchers at a California university have found a parasitic fly which causes honeybees to become disoriented and abandon their hives before dying, behavior which made one of the researchers compare them to zombies. Scientists believe this may be a contributing factor to Colony Collapse Disorder, which has decimated honeybee populations, affecting the honey market and the pollination of crops as well as raising concern about environmental toxins.

The insect version of a horror movie

The parasitic flies were discovered by chance when John Hafernik, professor of biology at San Francisco State University, collected some dead bees, found under a light on campus, as food for a praying mantis he had just captured. "Being an absent-minded professor, I left them in a vial on my desk and forgot about them. Then the next time I looked at the vial, there were all these fly pupae surrounding the bees."

The flies were later identified as Apocephalus borealis. The female A. borealis fly deposits its eggs into the bee's abdomen, and about a week later, mature fly larvae emerge from the host's head and thorax. Infected bees move their limbs in a jerky limb fashion and walk in circles. They leave their hives and seek bright lights as if they were moths rather than bees. They die shortly afterwards and as many as 13 parasite fly larvae may then crawl out from the body of their host.

One member of the research team, biology graduate student and study co-author Andrew Core, observed that the bees "kept . . . falling over. It really painted a picture of something like a zombie." The researchers found that bees which leave the hive to forage at night, rather than those that forage by day, seem most likely to become infected. In addition, the researchers believe the parasitic flies may multiply within a hive, infecting other members of the swarm, even pregnant queen bees.

The research team analyzed several hives in the both the Central Valley and Bay areas of Northern California and also some hives from South Dakota. Seventy-seven percent of the hives they sampled contained evidence of A. borealis. The scientists believe this may be a recent change in the behavior of this particular species of fly. The A. borealis fly has been known in the past to be a parasite of bumblebees and paper wasps but has not previously been known to inject its eggs into honeybees.

Double parasites, viruses and more

The researchers' findings add another clue to the mystery of CCD but also reveal how complicated the origins of that disorder are. Infected bees and their fly parasites were found to hold genetic traces of another parasite, Nosema ceranae. Analysis also revealed both parasite and host have a virus which causes wing deformities. These findings suggest that A. borealis may weaken hives in multiple ways.

The research team plans to use video monitoring and tiny radio tags to monitor hives for further research. Since they have so far only sampled hives from two states, they want to learn if the new parasitic behavior of A. borealis occurs in other areas. They hope to learn whether the "zombie bees" choose to leave the hive or if other members of the group sense their disease and drive them away to protect the swarm. They also hope to pinpoint the location in which bees become infected "We don't know the best way to stop parasitization, because one of the big things we're missing is where the flies are parasitizing the bees," stated Hafernik.

"We don't fully understand the web of interactions," said Hafernik. "The parasite could be another stressor, enough to push the bee over tipping point. Or it could play a primary role in causing the disease." Hafernik and Core's study was published in early January 2011 in the open access science journal PLoS ONE 
(Natural News, 2012)