YOSEMITE NATIONAL PARK, Calif. -- Hantavirus in Yosemite. West Nile virus in 48 states. Even a case of bubonic plague.
"I hear locusts are next," says Cathi Soriano of Seattle, who recently took Yosemite National Park off a road-trip itinerary.
Are we under siege?
Not
really, but the medical victories we've experienced over the past 100
years have made Americans forget that such diseases haven't gone away,
says David Dausey, director of the Institute for Public Health at
Mercyhurst Universityin Erie, Pa. "It's unsettling to realize that we're
not entirely safe from these things."
MORE: Yosemite hantavirus warning extends worldwide
The rise of hantavirus and
West Nile virus, neither even recognized in the United States before
1993, is making people check their window screens, stock up on bug spray
and rethink travel plans. In Yosemite this summer, hantavirus has
killed three people out of nine sickened. Nationally, West Nile virus is
the worst it's been since the disease arrived on our shores in 1999:
more than 3,545 illnesses and 147 deaths as of Thursday.
Extreme
weather patterns have played a big role in the two recent outbreaks, and
health officials worry more such events could be on the horizon because
of climate change.
Climate cycles very clearly play a part in
outbreaks, says Michael Osterholm,director of the Center for Infectious
Disease Research and Policyat the University of Minnesota in
Minneapolis. The question is at what point any given outbreak is being
caused by climate change or simply normal weather cycles. However, it's
clear that "eventually (climate change) will affect things, but is it
now? We don't know," he says.
At the same time, health officials
fret that the public health infrastructure of laboratories and public
health workers that tracks and responds to outbreaks is being cut. That
could make outbreaks harder to detect and control.
"The federal spigot is not just being cut off, it's being smashed," Osterholm says. "We've got a crash coming. We can see it."
In
the hantavirus outbreak at Yosemite, weather and a move to provide more
economical lodging for winter sports enthusiasts could be behind the
illnesses. Three deaths are worrisome but doctors are particularly
taking notice because they came in a tightly focused geographic cluster.
"It's
never happened before," says Pierre Rollin, a chief with the Centers
for Disease Control and Prevention's Special Pathogens Branch.
On a brilliant fall day, it's impossible to get into the park and not hear about hantavirus.
"They
gave me a pamphlet when I came through the main gate, then one when I
checked in (at Curry Village), and there was one on my bed when I got to
my cabin and one pinned to the wall. And there's one in the bathroom,"
says Rebecca Costello of Ambleside, England. "Those people up there,"
she says, pointing at rock climbers clinging to the Half Dome are "in a
lot more danger than I am here.""Now's probably the safest time to be
here," agrees Nicole Swedlow, 38, who runs a children's charity in San
Pancho, Mexico. "They've got people all over it."
Phillipe
Brachais, 30, of Antwerp, Belgium, has no worries about staying nearby.
"It's only three people dead, and millions come here every year," he
says.
His companion, Fabienne Verwerft, 29, says her only concession was to buy some hand sanitizer before they arrived.
There
have been some cancellations, but park visitors are still on track to
reach the September average of about 17,000 people a day, said Tom
Medema, chief of interpretation and education at Yosemite National Park.
But
in the background, epidemiologists, wildlife biologists and researchers
are catching and testing mice, taking environmental samples and
contacting people who stayed in the area -- those who got sick and those
who didn't -- to see how their visits differed.
Hantavirus has
long been known in the United States. Every year from 11 to 48 people --
mostly in the West and Southwest -- come down with it, and about 33% of
them die. But never in clusters, as at Yosemite. That's why the
National Park Service has sent letters and e-mails or made phone calls
to more than 260,000 overnight guests who stayed in the park since early
June to warn them, Medema said. So far, no park workers are known to
have come down with the virus, Medema said.
On Wednesday, the park
began a pilot survey to draw blood samples from approximately 100
employees to find out if they had been infected with hantavirus in the
past. Because most people who get hantavirus don't have symptoms, it's
possible others have gotten it before but no one knew. Once the pilot
survey is completed the park hopes to open it to all staffers. This "may
make an important contribution to our knowledge about this rare virus,"
Medema said.
The virus is carried by deer mice, which live
across the United States. People get it by breathing in aerosolized mice
droppings and dried urine -- that is, mouse dust -- so victims have to
be in close contact with the mice or their nests. It is not transmitted
between humans.
The Yosemite outbreak is still a medical mystery,
one that dozens of wildlife and health experts are combing the park to
solve. It is known that wet summers give mice ample food, allowing
populations to climb. Follow that with a mild winter, as last winter
was, and it's a problem.
"It's the adults who survive the winter
who transmit the virus," says Danielle Buttke, a veterinary
epidemiologist with the U.S. Public Health Service in Fort Collins,
Colo., who was in Yosemite investigating the outbreak. If the summer
then is especially dry, all those mice are looking for food and homes --
which they found in the tent sites at the park's Curry Village.
The first big U.S. hantavirus outbreak in 1993 "was a very wet summer followed by a mild winter," Buttke says.
In
2009, in the category of possible plain bad luck, the park added
insulation to some tents to replace winterized cabins destroyed in a
massive rock fall in 2008.Unfortunately, mice love to live in
insulation, says Gregory Glass, a hantavirus specialist and professor of
infectious disease ecology at Johns Hopkins University in Baltimore.
"It
may just be one of those situations where, historically, when they
didn't insulate them, it wasn't that attractive for the mice to sit and
stay," he said. "But this one little tweak in the design made just that
much of the difference for mice."
West Nile has certainly had a
bumper year because of the weather. The Culex mosquito that carries the
virus prefers breeding in the murky bottoms of drying pools and water
sources -- exactly what happens in droughts. And this year drought has
scorched the nation at levels surpassed only twice before, according to
the National Climatic Data Center.
People such as Osterholm worry
that we're gutting our ability to fight such outbreaks when more extreme
weather is in our future. With West Nile virus, a mosquito-borne
disease, cutbacks have hit local mosquito abatement districts
nationwide, from the loss of a few staff members to the closing of North
Carolina's entire mosquito Pest Management Section. CDC's Vector Borne
Diseases group, which works on West Nile virus, among other diseases,
has lost $14 million in funding since 2005, 38% of its budget.
"It's
easy to count how many police or firefighters you have," Osterholm
says. But no one's counting how many public health people who can
respond to a crisis are losing their jobs. "We're going to wake up one
morning and say, 'There's a big outbreak somewhere,' and people will ask
who's responding, and we'll say, 'We don't know -- we don't really have
anyone there.' "
The one episode this summer that didn't appear
to be anything other than normal was the case of bubonic plague in
7-year-old Sierra Jane Downing of Pagosa Springs, Colo. Doctors believe
she caught it from fleas off a dead squirrel she encountered while
picnicking with her family.The bacterium that causes plague, Yersinia
pestis,is found in rodents and their fleas in many parts of the world,
including the United States. Every year five to 15 people catch it,
according to the CDC.
Doctors at Rocky Mountain Hospital for
Children in Denver, where she was being treated, quickly realized she
had the plague and gave her the appropriate antibiotics. She went home
after 2½ weeks in the hospital.
USA Today