Virus Attack Continuing at Yosemite Natl. Park

July 8, 2013 by · 2 Comments 

Deer mice (Peromyscus maniculatus) are carriers of hantavirus pulmonary syndrome (HPS) in Yosemite and other parts of the U.S. Photo from Centers for Disease Control and Prevention.

The weapons of choice against the tiny mice that run around Yosemite National Park carrying a potentially fatal virus include disinfectant, peanut butter and 20 years’ worth of animal science.

Last year 10 people became ill with hantavirus, an outbreak concentrated among a cluster of canvas-walled tent cabins in Yosemite’s Curry Village, a popular destination on the valley floor, the Orange County Register reported. Three people died in what is the largest rash of cases related to the Sin Nombre strain of the virus, which was discovered in 1993. The other seven victims survived.

DNC Parks and Resorts of Yosemite, which operates the lodgings and other businesses in Yosemite National Park, has gone to great lengths to prevent another outbreak. Ninety-one Signature tent cabins, the relatively new structures that turned out to be well-suited for harboring infected mice, were torn down earlier this year.

Park employees now take more time to clean structures — at least 15 minutes for the Curry Village tent cabins — and watch for mouse droppings. Park authorities also have redoubled efforts to educate visitors about the importance of stowing food so mice, as well as bears, deer and other animals, can’t get to it. All over the park, there are fliers urging guests to take precautions.

The preventive surge has brought a comeback for one of the nation’s greatest natural treasures, thanks in part to a massive outreach campaign. And the visitors are undeterred by last summer’s unprecedented outbreak.

“The transparency of the National Park Service reinforces my confidence that they’re eradicating the problem and keeping everyone safe,” said Kevin Kearn, 45, a retired Army lieutenant colonel from Huntington Beach.

No one, not even the biologists who poured into the valley after the first hantavirus cases were reported, can explain exactly why so many people developed infections in such a short time. And despite the intense preventive efforts, there’s no guarantee there won’t be more cases.

“When you have that many humans, chances are there’s going to be a food source,” said Danielle Buttke, a veterinary epidemiologist at the National Park Service in Fort Collins, Colo.

The “reservoir” for the outbreak was traced to the deer mouse, which is common all over the West. About 14% of the deer mice in Yosemite have the Sin Nombre strain of the hantavirus.

The virus doesn’t spread to any other animals, and the virus doesn’t exist in common house mice.

But it’s in the deer mouse feces, urine and saliva, and if any of those substances gets stirred up — say, by sweeping along a floor — it can get aerosolized. If enough of it is inhaled, infection can occur.

In 2009, the park built 91 Signature tents, which featured canvas on the outside, then a layer of insulation, then a layer of sheet rock. The goal was to have a warmer-cabin option in wintertime for guests who wanted it. Mice were able to get into the insulation and hide, and the virus came from the walls.

“That particular kind of structure, we hadn’t anticipated a rodent infestation would be there, but that was the smoking gun in this case,” said Barbara Knust, an investigator with the Centers for Disease Control and Prevention’s infectious-disease branch in Atlanta.


A Closer Look at Yosemite Hantavirus Fight

May 28, 2013 by · 1 Comment 

Curry Village has become ground zero of a multimillion-dollar effort to make Yosemite National Park safe — or as safe as any rural place can be — from an illness carried by mice who can burrow into a hole the width of a pencil. Changes to the park’s far-flung facilities will get tested this summer, as an expected 1.8 million visitors fan out across its 1,200 square miles and share turf with all sorts of wild beasts, the Los Angeles Times reported.

The park visitors who contracted hantavirus had inhaled large quantities of dust containing urine, saliva and fecal matter from infected deer mice. To try to keep that from happening again, workers have been plugging crannies in buildings, hanging screens on staff and guest lodgings, and reinforcing “bear boxes,” all to keep the little critters from nesting anywhere near people.

It’s an undertaking that’s considerably more difficult than guarding against ferocious predators, said Mark Gallagher, environmental manager at Yosemite for Delaware North Cos., which operates Curry Village and other lodging facilities in the park.

“Keeping a bear out is easy — your enclosure just has to be strong,” Gallagher said. “With a mouse, you really have to pay attention to detail.”

Click here to read the entire story.




Feds: Hantavirus Outbreak Response Proper

May 21, 2013 by · Comments Off on Feds: Hantavirus Outbreak Response Proper 

Federal investigators probing the hantavirus outbreak blamed for three deaths at Yosemite National Park recommended on Monday (May 20) that design changes to tent cabins and other privately run lodging first be reviewed by National Park Service (NPS) officials.

The report released by the Interior Department’s Office of Inspector General found that park officials responded to last summer’s outbreak appropriately and within department policy, the Macon (Ga.) Telegraph reported.

“When the outbreak was identified, NPS mobilized to contain and remediate the outbreak and to prevent further outbreaks,” Mary Kendall, a deputy inspector general, wrote in a letter attached to the report.

Still, the report found that current policy didn’t require park officials to approve design changes made to the “Signature tent cabins” by concessionaire Delaware North Cos. Parks and Resorts, which added rafters and wall studs to the structures.

Investigators determined that deer mice, which can carry the illness, nested inside the double walls of the new tents in Yosemite’s family friendly Curry Village.

At least eight of the nine tourists who fell ill stayed in the tent cabins.

Because the changes to the cabins were considered routine maintenance, current park service policy did not require prior approval, the report found.

The report also recommended that the park service begin cyclical pest monitoring and inspections of all public accommodations.

While there is a current pest monitoring program at Yosemite, Delaware North was responsible for Curry Village, which was not considered at high risk for hantavirus.

The company issued a statement late Monday saying it would follow the recommendations in the report.

“DNC Parks & Resorts at Yosemite has consistently worked hand-in-hand with the National Park Service and public health officials on this issue,” spokeswoman Lisa Cesaro said in the statement. “The Signature Tent Cabins have been removed from Curry Village. We are following the recommendations by the National Park Service, which were developed in consultation with the California Department of Public Health and the Centers for Disease Control and Prevention.”

Prior to the outbreak, Delaware only responded to pests in the cabins when visitors or housekeeping staff complained, the report said.


Suit Filed Over Yosemite Hantavirus Outbreak

April 30, 2013 by · Comments Off on Suit Filed Over Yosemite Hantavirus Outbreak 

A multi-million dollar lawsuit has been filed over the hantavirus outbreak inside Yosemite National Park last year, KFSN-TV, Fresno, Calif., reported.

The first court date is set for May 30. The lawsuit alleges Cathy Carrillo of Chino, Calif., contracted the virus while staying in Curry Village last June.

Carrillo claims she has a million dollars’ worth of medical bills and now suffers from diminished lung capacity and low energy.

Carrillo is seeking $3.25 million from DNC Parks and Resorts at Yosemite. The hantavirus outbreak caused a worldwide scare among Yosemite visitors. Three died and several others were sickened by the illness.

230,000 people around the world were warned that they may have been exposed to the virus while visiting Yosemite.

Click here to read a story summarizing the hantavirus outbreak at Yosemite.


A Look Back at Yosemite’s Hantavirus Outbreak

December 19, 2012 by · Comments Off on A Look Back at Yosemite’s Hantavirus Outbreak 

Sunset over Half Dome, Yosemite National Park

On Dec. 10, Yosemite National Park in California began demolishing 91 tent cabins in Curry Village, a rustic encampment of 408 canvas-sided cabins jammed into a pine-and-cedar glade near the sloping shoulders of Half Dome. It was here that an outbreak of hantavirus began last summer, infecting at least 10 people and killing three, reported.

But on Sunday, June 10, 2012, the campground seemed idyllic. That weekend held all the promise of early summer. The Curry Village swimming pool was open. The smell of hot dogs and nachos curled out of the snack bar. The sun bounced off the face of Glacier Point. Kids in “Go Climb a Rock” T-shirts shouted and chased each other on bikes.

Sometime that day, a 49-year-old woman from the Los Angeles area arrived at Curry Village’s front desk, a plain wood-floor office that’s often cacophonous with the sound of staffers checking guests in and out. A clerk handed her a key to one of the 91 “signature tent cabins” that opened three years ago — the “new 900s” as they were collectively known. Unlike the older cabins, which are sided with single-ply vinyl-coated canvas, the signature cabins boasted double-wall plywood construction and propane heaters, making them warmer and quieter than the older units.

Off she went, this Southern California lady, to enjoy her Yosemite vacation. We’ll call her Visitor One.

About the same time, another guest checked into Curry Village. He was a 36-year-old man from Alameda County, Calif., which encompasses Berkeley, Oakland, and the East Bay region. He was given the key to a cabin close to Visitor One’s. He dropped off his things and went about his business. We’ll call him Visitor Two.

We don’t know exactly how Visitors One and Two spent their four days in the park. Medical confidentiality laws forbid public-health officials from releasing their names, and they and their families have chosen to keep their stories private. Maybe they hiked to the top of Half Dome or enjoyed the giant sequoias of the Mariposa Grove. By the following Wednesday, June 13, both visitors had checked out of their Curry Village tent cabins and left the park.

Around Yosemite the summer unfolded quietly. The search-and-rescue team went out on minor events: an ankle fracture on the Panorama Trail, a fallen hiker on the Half Dome cable route. Rangers kept a wary eye on the Cascade Fire, a lightning-sparked wilderness blaze that smoldered through a red fir forest.

Then, in late June, Visitor One fell ill. She might have felt like she had the flu: chills, muscle aches, fever, headache, dizziness, fatigue. The flu goes away after a few days. This didn’t. We do know that, back home, she went to see her doctor. When presented with Visitor One’s symptoms, most physicians would have dismissed it as the flu or, at worse, low-level pneumonia. Her doctor didn’t.

They talked about what she might have picked up and where. She mentioned her Yosemite trip. The doctor took the unusual step of calling Charles Mosher, a public-health officer for Mariposa County, which encompasses Yosemite, and asking if there were any known hantavirus cases in the area. “Based on her history and symptoms, [hantavirus] was a definite possibility,” Mosher recalled, so he and Visitor One’s doctor agreed that starting treatment for the virus while awaiting lab confirmation was the prudent way to go.


Report: Hantavirus May be Sign of the Times

October 1, 2012 by · Comments Off on Report: Hantavirus May be Sign of the Times 

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?

According to a USA Today report, 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.”

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.


Blood Tests Could Offer Hantavirus Clues

September 28, 2012 by · Comments Off on Blood Tests Could Offer Hantavirus Clues 

Public health officials have begun examining blood samples and questionnaire results from dozens of Yosemite National Park workers who volunteered for a study designed to shed light on an unprecedented outbreak of deadly hantavirus.

Reuters reported that this week’s screening, which involved 96 workers, is the latest effort by officials to uncover clues about the rare, mouse-borne lung disease that has infected at least nine park visitors and killed three since June.

“This is a unique opportunity to learn more about potential exposure to hantavirus from the people who lived and worked in close proximity to this cluster of cases,” park spokesman John Quinley said Thursday.

One aim is to help researchers design a study of the California park’s more than 2,500 workers in a search for clues about how the virus infects people and how to prevent it.

Among the lingering questions over the outbreak is why hantavirus infected park visitors while sparing employees.

All but one of the nine infected visitors stayed in Curry Village in double-walled, insulated tent cabins later found to be infested with deer mice. The tiny, white-bellied mice carry the airborne virus in their droppings, urine and saliva.

The park closed the infested tent cabins at the end of August, after learning of two of the hantavirus deaths.

This week’s screening will examine park workers’ blood for antibodies signaling exposure to the hantavirus. Employees also answered questions about where they live, their contact with mice, their job duties and their hantavirus training, Quinley said.

“We’ve had a lot of employees go through hantavirus training,” he said. “We’re interested in knowing if the training works.”

The voluntary study is part of a broader scientific effort that will include the first whole-genome sequencing for the hantavirus strain t h at struck Yosemite over the summer. It marked the biggest cluster of cases since the disease was first identified in the United States in 1993.

At that time, when hantavirus pulmonary syndrome infected healthy young adults in the Four Corners region of Utah, Colorado, Arizona and New Mexico, Navajo elders linked the outbreak to an abundance of pine nuts and an explosion of mice coming out for the feast.

Since then, more than 600 Americans have been diagnosed with hantavirus pulmonary syndrome. The incurable disease kills more than a third of those infected.

To date, humans have never been known to transmit the virus. People can inhale the hantavirus when mice droppings mix with dust, especially in confined, poorly ventilated spaces.


Scientists Seek Clues on Hantavirus Outbreak

September 25, 2012 by · Comments Off on Scientists Seek Clues on Hantavirus Outbreak 

Scientists seeking a cause for the deadly hantavirus outbreak among visitors to California’s Yosemite National Park over the summer are investigating whether a spike in the deer mouse population, combined with the unusual design of some tent cabins that enabled mice to nest in the insulation, made it easier for people to contract the rare disease.

The San Jose Mercury News reported that experts consider another theory — that the virus recently mutated and became more transmissible to humans — a long shot.

The initial findings of federal health authorities who have sequenced the virus’ genome using samples from those who fell ill indicate that the virus has not changed, said Danielle Buttke, a veterinary epidemiologist with the National Park Service. But others continue to explore that theory until it can be definitively ruled out.

UC San Francisco researcher Dr. Charles Chiu agrees that the prevalence of deer mice and the tent cabin design are the most likely culprits.

But Chiu, who directs the UCSF-Abbott Viral Diagnostics and Discovery Center, plans to have his lab sequence genomes from all of the visitors who fell ill, as well as those in deer mice gathered in the Sierra, Bay Area and throughout California. He will then compare the current strains to historical ones.

“I think it’s more likely to be a change in the environment, but without doing the sequencing, I can’t exclude that and that’s why we’re doing the study,” said Chiu, an assistant professor of infectious diseases.

Unlike the flu virus, which changes so often the vaccine must be revised every year, the hantavirus has been relatively stable, Chiu said. Yet the possibility that a mutant or variant strain could develop still exists.

“The question really is: Do we have the whole story here?” Chiu said.

One thing nearly everyone agrees upon: The cluster of cases linked to Yosemite is highly unusual.

Nine people who spent at least one night at the park since June became infected with the virus, and eight went on to develop hantavirus pulmonary syndrome.

Three people died, and the rest are recovering. No vaccine, treatment or cure exists. Doctors try to keep people alive long enough for their immune systems to rid their bodies of the virus.

Seven of the infected people had stayed in the “signature” tent cabins in Curry Village. The cabins’ double-walled design enabled mice to nest undetected in the insulation between the two walls, Buttke said.

Yosemite Workers May Receive Free Testing

September 21, 2012 by · Comments Off on Yosemite Workers May Receive Free Testing 

Three people who work in Yosemite National Park have experienced flu-like symptoms that prompted them to get tested for hantavirus, health officer Dr. Charles Mosher said at Tuesday’s Mariposa County Board of Supervisors meeting.

The Mariposa Gazette reported that while initial tests came up positive, a set of second, more-precise tests showed the three had not been exposed to the deadly Sin Nombre strain that causes hantavirus pulmonary syndrome, or HPS.

Yosemite employees may soon be offered free hantavirus tests that could help experts learn more about the outbreak, Park officials said.

Officials were still working out the details of the plan this week, NPS spokesperson Vickie Mates said.

“If the survey does go forward, we will notify our employees of this voluntary opportunity,” Mates said. “The results of the proposed survey, a common epidemiological tool, may make an important contribution to our knowledge about this rare virus.”

Testing would be conducted by California’s Department of Public Health.

Two of the nine recent Yosemite hantavirus cases involved individuals who did not come down with full-blown, lung-involved HPS. According to a 2007 article in the journal Emerging Infectious Diseases, close to one percent of workers who come into close contact with deer mice test positive for hantavirus— even if they never felt ill.

Speaking at Tuesday’s meeting, Dr. Mosher said news about the three tests shows that some park workers have been worried about possible exposure to the virus.

Medical and public health experts are intensively studying the Yosemite outbreak.

Yosemite Officials Staying on Top of Hantavirus

September 20, 2012 by · Comments Off on Yosemite Officials Staying on Top of Hantavirus 

Federal and state health officials investigating the hantavirus outbreak at Yosemite National Park say it could take several weeks to determine how nine visitors contracted the illness – three of whom died.

FOX News reported there is some evidence the park’s population of deer mice, which carries hantavirus, has grown significantly. Park officials have been trapping and killing deer mice for the past few weeks. They said that while the percentage of those testing positive hasn’t changed, there are simply more deer mice, which could translate into a greater risk of exposure for people.

Health officials are looking at Curry Village, the popular campsite where all but one of the cases originated. They found deer mice in the insulated walls of some tent cabins. Ninety-one cabins are now closed indefinitely.

Symptoms of hantavirus mimic the flu, and a patient who waits to seek treatment can go from bad to worse – fast. Why some people got sick and others did not remains a mystery.

“The cases have been (visitors from) distinct cabins, different cabins, different families, and along with that, we know there are people that stay with case patients in tents – patients that didn’t get sick,” said Danielle Buttke, a veterinary epidemiologist for the National Park Service.

This is not the first hantavirus outbreak at Yosemite, but given the cluster of infections, it is the most serious. There are usually just a handful of cases each year in the United States, and it’s particularly worrisome because there is no cure or vaccine.

One-third of hantavirus cases are fatal, Dr. Charles Chiu, an infectious disease specialist with the University of California, San Francisco, told Fox News.

Epidemiologists studying hantavirus said all the attention on the Yosemite outbreak could help patients in the future.

“It is my hope that this particular cluster of cases will drive more interest in developing a vaccine or drug that would be effective against this very deadly disease,” Chiu said.

Park officials are handing out fliers with information about how to avoid getting sick. Tips include staying away from deer mice and their droppings. The park is also emailing about 230,000 people around the world who stayed overnight at the park since early June, giving them information about the virus and how it is spread.

The park averages about four million visitors each year, and park attendance is down compared to last August – although last summer was a huge tourist season because of the large snowpack-fed gushing waterfalls.

Now that the falls are dry, visitor numbers are on par with 2010 and 2009 figures, park officials said; however, park rangers and staff members have noted the scare has caused some people to cancel their hotel reservations.




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