2013-01-31 / Front Page

Hantavirus antibodies found in at least one Yosemite worker

Erik Skindrud / GAZETTE EDITOR

A small number of Yosemite National Park workers can now boast that they survived an extremely close encounter with hantavirus.


At least one Park worker who gave blood in October has come up positive for antibodies to the Sin Nombre strain that causes the deadly illness, California Department of Public Health spokesman Matt Conens has told the MARIPOSA GAZETTE. 


Hantavirus pulmonary syndrome, or HPS, killed three Yosemite visitors and sickened six more last summer. No Park workers were among the total.


Conens did not give the precise number of workers who tested positive, but said it was “fewer than one percent” of 569 employees who answered questions and donated blood as part of the study.


Most who took part in the voluntary testing work for the National Park Service. An unknown percentage work for Park concessionaire Delaware North Companies.


“This is a pretty major finding,” Dr. Charles Chiu of UC San Francisco’s Department of Medicine and a leading virus researcher, said when told of the result.


“One percent is still fairly rare, but it could be possible that there’s a higher rate of these subclinical infections than we thought,” Chiu said. 


Questions remain, however. Researchers will want to test a wider sample of the population to see how many Californians have the virus antibodies. Scientists may also test family members of workers who tested positive.


Also called “inapparent,” subclinical refers to cases that are mild enough to escape notice. Of the nine cases in Yosemite last year, two did not display symptoms of full-blown HPS, previous reports noted.


This week’s announcement may raise some eyebrows in the Park, but is not unprecedented. A 2007 study in the journal Emerging Infectious Diseases found Sin Nombre antibodies in three of 387 workers who had close exposure to deer mice in the American Southwest. That rate of exposure works out to .8 percent--the same ballpark as the recent Yosemite results.


The 2007 study found that none of the workers with hantavirus antibodies had used protective equipment like gloves or respirators. 


“The overall probability of acquiring HPS when working with rodents appears to be 1 in 1,412,” the authors wrote.


At least one of the hantavirus-positive workers from the 2007 study recalled being seriously ill with symptoms that resembled HPS. He or she had been hospitalized, but never diagnosed with the illness.


The California Department of Public Health researchers are in touch with the Yosemitep workers who tested positive, Conens said. “Due to privacy laws,” the department cannot release any further details about the workers--even their precise number.


“(We) may contact some employees to ask additional questions related to exposure to mice and potential risk factors,” the spokesman said.


The department’s full report on the Yosemite outbreak is expected this spring or early summer, Conens said. 


Look for more on the Yosemite hantavirus findings in the Feb. 7 GAZETTE.

Centers for Disease Control (CDC) worker Scott Smith uses protective gear while working with a Biosafety Level 4 (BSL-4) pathogen like hantavirus. Photo: CDCCenters for Disease Control (CDC) worker Scott Smith uses protective gear while working with a Biosafety Level 4 (BSL-4) pathogen like hantavirus. Photo: CDCAn image taken with a transmission electron microscope shows deadly hantavirus particles. Photo: CDCAn image taken with a transmission electron microscope shows deadly hantavirus particles. Photo: CDC

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This is interesting. I

This is interesting. I wonder how many things we could show positive antibodies for if we were tested. Valley Fever comes to mind. Some people die and others don't know they were exposed. I may have TB encapsulated within me, but test negative for it. Rather than this article being alarming, I find it exciting that our immune systems do this. (even if mine over-reacts sometimes)

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