State bioterror monitoring expanded to animals

By Warren King
Seattle Times medical reporter

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As part of the state's biological-warfare defense, state veterinarians recently began monitoring unusual small-animal deaths for evidence of tularemia, plague or other diseases that could be caused by lethal agents.

"We're hopeful we'll be on the cutting edge, that we would find out (about an attack) before there would be any infection of humans," said Dr. Mira Leslie, the state Department of Health's public-health veterinarian.

Small animals likely would show symptoms and die faster than humans after being exposed to a lethal biological agent, Leslie said.

Funded by a $75,000 grant from the Centers for Disease Control and Prevention, the project uses citizen reports of dead wildlife to collect animals for examination. Veterinarians from the state Department of Fish and Wildlife receive the reports, sometime retrieve the animals, conduct preliminary exams, and then send them to a Washington State University lab for extensive analysis.

"If the body can be preserved, we send it in," said Dr. Briggs Hall, a Fish and Wildlife veterinarian, who has shipped critters ranging from rodents to a porcupine.

"I think that if someone were to introduce a disease into the environment, the fact that we're looking ... would be of great benefit," Hall said.

Officials of the Department of Homeland Security and other intelligence experts have warned repeatedly that terrorists could use biological agents in an attack.

The primary means for detecting such an attack is by monitoring human illnesses. King County created a bioterrorism surveillance system even before the Sept. 11, 2001, terrorist strikes. Other counties have established their own systems since then. The backbone of the system is primary-care physicians and hospital workers, who have been asked to quickly report suspicious symptoms to public-health authorities.

In the animal reporting system, plague and tularemia are receiving special emphasis because they are considered among the highest risks for an attack and can infect both animals and humans. Anthrax, often mentioned as a threat, also could be detected in animals, especially cattle, sheep and goats, where it occurs naturally.

Plague, tularemia and anthrax are designated "Category A" agents by the CDC because of specific criteria: They can be easily disseminated or transmitted person to person, can cause many deaths, and can cause panic.
 
Plague, one of the most feared agents, is caused by bacteria, Yersinia pestis, sometimes found in rodents and their fleas in many areas of the world, including in the United States. About five to 15 human cases a year are reported in the U.S., usually in bubonic form, which is transmitted by flea bites. The last Washington state case was in 1984 in a man who had been skinning bobcats in the White Pass area.

A terrorist attack could disperse the bacteria into the air, where they could be inhaled and cause pneumonic (in the lungs) plague, according to the CDC. The bacteria can survive for up to one hour in the air. Symptoms take up to six days to appear, so infected people could travel far from the site and spread the disease through coughing or sneezing.

Plague is usually fatal unless treated with antibiotics within 24 hours of onset. Typically, those who are infected experience fever, weakness and rapidly developing pneumonia. There is no vaccine.

Tularemia, also known as rabbit fever, occurs naturally in rabbits, hares and rodents. About 200 cases of human tularemia, usually transmitted by tick or deerfly bites, are reported in the U.S. each year, including two to five in Washington. It is caused by bacteria, Francisella tularensis; is highly infectious; and could be disseminated by bioterrorists through the air, says the CDC.

If inhaled, tularemia bacteria can cause abrupt fever, headache, muscle aches and potentially fatal pneumonia, if not treated quickly with antibiotics. No vaccine is available.

Leslie, the public-health veterinarian, said the new surveillance system looks for "die-offs" of vulnerable animals — a group of wild animals dying quickly without apparent explanation.

"We want to know, too, what the natural hosts for the diseases are," she said. Establishing a database of information on wildlife deaths will help veterinarians to determine quickly which infections are natural and which might be from bioterrorism. Wildlife biologists already know, for example, that coyotes eat rodents, and blood samples from dead coyotes sometimes reveal antibodies to plague. That shows they are not vulnerable to the disease.

Leslie said the project also will ask some veterinarians to take blood samples from rural cats they treat and send the samples to the laboratory. Some cats survive plague, and researchers want to see how often plague antibodies show up from the animals' consumption of rodents.

That will provide a better idea of the natural occurrence of the disease in rodents and help veterinarians recognize the symptoms in cats that actually have plague.

"We're linking vets into the system because animal and human health are interconnected," Leslie said. "Vets can be an important part of the eyes and ears of public health in terms of our surveillance."

The project also will serve as a watchdog for emerging illnesses in pets and humans, Leslie said. Unusual, unexplained symptoms may indicate the introduction of a disease from abroad, such as with the monkeypox outbreak a year ago.

In that outbreak, at least 71 human cases of the disease were reported in six Midwestern states after a Texas exotic-pet dealer imported infected Gambian rats and dormice from Ghana. Those creatures, in turn, infected prairie dogs widely sold as pets by an Illinois dealer. At least 18 of the patients were hospitalized with the disease, which is similar to smallpox but not as deadly.

Warren King: 206-464-2247 or wking@seattletimes.com