New, Fast-Evolving Rabies Virus Found -- And Spreading

[Watchman]

New, Fast-Evolving Rabies Virus Found -- And Spreading
Anne Minard
for National Geographic News
May 4, 2009

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Genetic studies suggest foxes are also spreading the new strain to each other, though the results have not yet been peer reviewed.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

 

[Watchman]

The mutant rabies strain seems to be spreading rapidly, but what really has the officials nervous is the potential for it to jump species and pass on to humans. Given the mutation, you wouldn’t necessarily need to get bitten by a fox to catch the disease from him, nor would you need to bite your beloved, as in the shock horror film “Rabid”, to pass it along the human chain. According to Hinh Ly, a molecular virologist at the Emory University School of Medicine in Atlanta, this should be a “major concern.” The problem is that foxes range far and do well in habitats in and around suburban areas. Skunks commonly live under houses in these same areas. Since suburban sprawl has pushed considerable numbers of these animals into congested neighborhoods, the chances for contact between infected animals and pets and humans is real.

Of course, the disease also can be spread by bites (it is not uncommon for hikers to be attacked by rabid animals, for example). But even scarier is the fact that as more animals get infected and congregate, the possibility that the virus will mutate further increases, potentially spawning a new and more dangerous form that could spread across species.

Officials in Arizona are on the case, trying to prevent an outbreak among pets and people. In the Flagstaff area, they declared a 90-day pet quarantine that required all dogs to be kept on leashes and all cats to be kept inside. Unfortunately, funds to vaccinate wildlife have been cut due to the recession, as have funds for public vaccination programs. Meanwhile, it’s been an active year for “normal” rabies — even in places like New York City. Recently, 39 rabid raccoons turned up in Central Park and triggered the city to begin trapping the animals and vaccinating them.

By comparison to rabies, swine flu seems like a benign illness. Rabies causes pain, vomiting, insomnia, and the famous signs of fury — thrashing, unquenchable thirst, drooling, spasms, and aggression; and once symptoms appear, death is swift. But health officials don’t expect an imminent human pandemic, because unlike flu, rabies has a very long incubation period. It typically takes 30 to 60 days from the time of exposure to arrival of symptoms, giving individuals plenty of time to get vaccinated — if they know they’ve been exposed. That’s why only about five individuals die of normal rabies in the US annually, though 18,000 get exposed and seek treatment. In other words, most people know enough to get help if exposed to rabid animals or if they receive a bite, and the current treatment works. But what if the mutant strain crosses over to humans where infection doesn’t require a bite — merely social exposure? How would you know you need to get a shot then?

Should a new strain of the disease arise, the scientists may need to go back to the lab to develop something different. Meanwhile, it’s unlikely that you’ll have to evacuate your condo unit to avoid marauding hordes of rabid skunks any time soon. But down the road may be a different story.

 

[Watchman]

Maybe cross species transmission cause the Kallang Killings .