CNN Food and Health

Virus carried by mice is a mysterious killer


October 10, 1995
Web posted at: 12:25 a.m. EDT

From Correspondent Don Knapp

SAN FRANCISCO (CNN) -- State health officials in California are trying to learn more about a deadly virus that strikes people mysteriously and kills half of those it infects.


Biologists scour a Sierra Nevada campsite for a biological hazard. They search for a deadly virus carried by deer mice.

They don't have to look far. Statewide on average, 12 to 15 percent of all deer mice carry the Hanta virus. "We know enough its from deer mice to recommend to people who live in deer mice habitat, who may be exposed to deer mice, treat all mice as if they're positive for Hanta virus," said Ken Townzen, biologist.


Last month, Richard Boom, 55, died of a Hanta virus infection, three weeks after a Sierra Nevada outing with his family in their motor home. "The doctor told us he didn't have anything wrong with his heart. They ruled that out, but didn't know what they were treating him for. One o'clock, one thirty he was gone...that quick," said Carol Boom, Richard's wife.

Deer mouse

Hanta virus kills one of every two people it infects. No one knows why some people become infected and others don't. "The number one risk would be to have a live animal run in front of you, or over you while you're sleeping at night, or actually be there to infect you in real time," said Dr. Michael Ascher, of the California Department of Health Services. "The urine or feces or other things left around would be the next lower level of risk, and the third would be over some period of time." Inhaling dust while cleaning out a cabin tainted with infected mice droppings, for instance, or eating food contaminated by infected mice.

"I don't think he did anything to put himself in danger. So I don't know how to take precautions for it. I mean, just breathing any can kill you? I don't understand that," said Boom's daughter, Christine.

Hanta virus sickened 44 people in 14 states since last year. Experts say at least 60 people have died from the virus since 1980.

Health workers focused on Hanta after the virus was identified as the culprit in the mystery deaths of 11 people on a Navajo reservation in New Mexico and Arizona in 1993.

Before that, Hanta virus was well known as a killer outside the United States but undocumented inside the United States.

Researchers say avoid deer mice. But for anyone who spends any time out of doors, that would be difficult because deer mice live just about everywhere in the country, except the southeast. Richard Boom had no idea what killed him.

"Scary, very scary. Could have been any of us. He was perfectly healthy," said Carol Boom.

Researchers have tips to use to avoid rodent droppings when staying outdoors: Keep food in mouse-proof containers. Also, ventilate and disinfect closed cabins before using them.

Don't worry too much about those city mice. It's mostly their country cousins that spread the Hanta virus.

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