A state biologist arrived Tuesday in Orange County to help scientists devise safety precautions for use during field studies of the often-fatal hantavirus, which was discovered recently in blood samples taken from several rodents in the county.
The field studies could begin as early as this week, with laboratory work to follow.
Biologist Minoo B. Madon spent the afternoon conferring with county vector control officials and drafting a protocol to protect the research team that plans to trap and test rodents, which may be carrying the virus linked to 33 deaths nationwide.
The field and laboratory studies will follow up on tests made this month of stored blood taken last year from five deer mice trapped within the TRW Capistrano Test Site near San Clemente as part of a different research project. The blood contained antibodies that indicate the presence of the airborne hantavirus.
Testing has yet to show whether the hantavirus present in the Orange County rodents is the same strain that causes the flulike upper respiratory ailment that quickly worsens and often leads to death. Scientists have yet to completely isolate the often-fatal virus.
Local officials are quick to note, however, that although the blood samples were taken last year and stored for months, there have been no cases of hantavirus illness in Orange County.
“What it is like, is we have is a 500-piece jigsaw puzzle, and we have only five pieces to look at, and so far none of them fit,” said Madon, who also investigated the July hantavirus death documented in Mammoth Lakes in the Eastern Sierra.
County researchers were expecting to acquire safety equipment and begin the field study sometime in the next three weeks, but county vector ecologist Jim Webb said Tuesday that the timetable may be stepped up if the special gear can be acquired locally.
A full “moon suit” was worn during the Mammoth Lakes study, Madon said, referring to an enclosed hazardous materials suit provided by the Army during the capture and field dissection of 160 rodents.
“Those are the kind of measures you have to take if you are going to be working with something this hot,” he said. The need for such elaborate safety practices, Madon said, unfortunately slows down an already methodical process.
“It could take years,” Madon said. “There’s absolutely no background on this virus, so it could take years to (defeat) it.”
Very little concrete information is known about the virus, which can lie dormant in the human body for 45 days before striking. Once muscle aches, fever and respiratory problems begin, death from fluid-filled lungs can come in days or mere hours.
Webb said Madon will join the local team when they return to the site where the five mice were captured last year during a routine rodent population survey for Lyme disease. Any rodents found living within buildings on the 2,770-acre parcel will also be tested.
While the virus, which is spread by a fine dust emitted by deer mice droppings, has not been identified among indoor mouse species, Webbs said they will be checked on the chance that they contracted the virus from the nearby deer mice.
County scientists on Tuesday shipped the 11 rodent carcasses stored since last year’s Lyme disease survey to the Centers for Disease Control in Atlanta. The animals were all captured near the TRW facility as part of the countywide Lyme disease monitoring program and, like the blood samples, were stored until the hantavirus situation provided a reason to retrieve and examine them.
Included in the 11 is one of the five deer mice that tested positive for the virus, which will provide federal medical investigators with lung, kidney and liver tissue that may help isolate the vexing virus. Isolating the virus is the first step in combatting it.
Officials advise the public to avoid contact with all rural rodents, and suggest lightly misting droppings from above with a bleach and water mixture before wiping up. Face masks, rubber gloves and plastic bags should all be used during disposal.