GARDEN GROVE — A county scientist on Tuesday announced the first confirmed presence in Orange County of a mysterious virus spread by rodents, which has been linked to at least 31 deaths in the Southwest.
The hantavirus, which scientists believe is spread through airborne dust generated by deer mice droppings, has been discovered in the stored blood samples of five deer mice captured last year in a canyon outside San Clemente, county vector ecologist Jim Webb said.
The virus has been tied to one Santa Barbara County death and to deaths in Arizona, Colorado, New Mexico, Nevada and Texas. Two cases reported last month in Oregon and Louisiana, bringing the death toll to 33, suggest that the virus's parameters may be widening.
It is, however, possible that the federal Centers for Disease Control and Prevention in Atlanta found a different, less dangerous strain of the virus in the Orange County mice, Webb said.
Also, while the virus-carrying mice were captured as far back as February, 1992, there has been no documented case of illness in Orange County from the virus, which strikes initially with flulike symptoms but rapidly worsens.
Webb would not say exactly where the deer mice were found because a "major private site" is within several hundred yards of the trap site. Webb said he had agreed with officials of the company that he would not name it.
Test documents listed the capture site as Talega Canyon near Cristianitos Creek along Avenida Pico. The TRW Capistrano Test Site at 33000 Avenida Pico is the closest major facility of any kind, but company officials could not reached for comment Tuesday evening.
County vector control officials will visit the unnamed site in question Friday to speak to company officials and employees about any precautions that might be necessary, Webb said.
Holding up a small plastic gas mask in his Garden Grove laboratory, Webb said it is possible that employees at the unnamed site might be required to wear similar respirators.
"It's not out of the question," he said. "It looks like that might be a suggestion if the current state recommendations are adhered to. Right now, anytime you're in an area where you might be dealing with the virus, that's what they recommend. It all depends on how serious the infestation is around those buildings."
State health officials are expected to arrive in Orange County early next week to analyze the situation and "create a protocol," which may include issuing safety precautions, Webb said.
"It's really something you need to be careful with," he said. "There are cases where people have gone into a lab and within a few minutes they had the virus and got sick later."
Irvine resident George Wolff, 64, said he contracted the illness during a brief trek across a breezy, open field in Albuquerque in March. "I never saw any mice," said Wolff, who managed to fend off the virus that usually causes fluid to fill the lungs, leading to suffocation. Doctors are unsure how Wolff, who lost 27 pounds, survived.
Scientists say there may be many more unnoticed, unreported cases of the hantavirus, which would push the illness, and perhaps fatality rate, higher.
The five samples that tested positive were among 153 vials of rodent blood that had been gathered during the last few years by the Orange County Vector Control District during an ongoing study of lyme disease among area rodents. In total, 13 deer mice, or Peromyscus maniculatus, were sampled at the site that yielded the five hantavirus carriers in February, April and July of 1992.
That ongoing survey, the only one of its type performed by a Southern California county, was halted in August when California health officials, alarmed about the hantavirus, issued a statewide advisory message telling inspectors not to trap any more mice until better safety precautions were in place.
The state Department of Health Services recommended last month that homes with deer mice be cleaned thoroughly of any accumulated droppings. The droppings should be misted from above with a mixture of one part household bleach and three parts water.
After the misting, which helps prevent dust from rising off the feces, the droppings should be wiped up and placed in a double plastic bag before disposal. Dry droppings should not be swept or handled, the advisory states, because of inhalation risks. Dust masks and rubber gloves are also advised.