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Deadliest, Rarest Form of Plague Contracted Near Denver

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July 14 (Bloomberg) -- A rare airborne form of the plague that can spread through coughing and sneezing has infected a Colorado man, and state health officials are searching for other possible cases.

The man, who hasn’t been identified, is infected with pneumonic plague, an inhaled form of the disease, the Colorado Department of Public Health and Environment said July 9 in a statement. It’s the first case of pneumonic plague seen in the state since 2004, said Jennifer House, a spokeswoman for the department. The man may have been exposed in Adams County near Denver, the department said.

Plague, which can be fatal if left untreated, spreads most often through flea bites and continues to spread in parts of Africa, Asia and South America. Only seven people are infected in the U.S. each year. The Colorado man has been hospitalized and treated, and is no longer infectious, House said.

“He’s on treatment long enough to not be transmissible,” she said in a telephone interview. He may have contracted the illness from his dog, she said, which died suddenly and has also been found to carry the disease.

“We don’t think it’s out in our air,” House said. “We think it’s in our dead animal populations and dead rodent populations.”

The disease occurs when a bacterium named Yersinia pestis infects the body, according to the U.S. Centers for Disease Control and Prevention. The difference between the pneumonic and bubonic varieties is that the bacteria take hold in the lungs in the first case, rather than underneath the skin through insect bites. Both types can be treated with antibiotics.

State Investigating

The state is working “to investigate the source of exposure and to identify those who may have been exposed through close contact with the individual,” the Colorado health department said in its statement. “Any individuals exposed will be recommended for antibiotic treatment.”

Mark Salley, a spokesman for the department, said yesterday there was no update on the investigation or the number of cases.

Plague first came to the U.S. in about 1900 on ships infested with rats, which can carry plague-carrying fleas, according to the CDC website. The last urban outbreak of plague in the U.S. occurred in Los Angeles in 1924 and 1925, CDC said. Rare plague infections occur in a few Western rural areas, including northern New Mexico, northern Arizona, southern Colorado, California, southern Oregon, and far western Nevada, according to the Atlanta-based agency.

Colorado Cases

Colorado has had 60 cases of all types of plague since 1957, and nine people have died, the state said.

“The reaction is leaning toward people who are tired of the protection of prairie dogs on some level,” said Jim Siedlecki, director of public information of Adams County. “Most people look at them as cute little dogs on the side of the road, but in rural Adams County they are looked at as a rodent who damages crops and is potentially plague-ridden.”

Adams County, home to 470,000 residents, with 425,000 living in the Denver metro area, is one of Colorado’s fastest-growing counties and among the 20 fastest-growing counties in the nation.

Untreated plague is fatal, and antibiotics have to be given within 24 hours of the first symptoms to reduce the chance of death. Symptoms of the disease include fever, headache and chest pain, along with a pneumonia that develops rapidly causing shortness of breath, chest pain and bloody mucus, according to the CDC.

No Vaccine

There is no vaccine available for plague in the U.S. The bubonic form is the most common and is best known for its outbreaks in the Middle Ages. Bubonic plague occurs when a person is infected through the skin, usually through the bites of fleas.

Colorado officials recommend that residents keep pets away from wildlife, especially dead rodents. The plague can spread from animals after a large die-off of prairie dogs, when fleas with the bacteria seek new hosts, according to the state.

“The message we’re trying to get out is that the plague bacteria is present here in Colorado, and to take necessary precautions to avoid getting infected,” House said.

To contact the reporters on this story: Sonali Basak in New York at; Jennifer Oldham in Denver at

To contact the editors responsible for this story: Reg Gale at Bruce Rule, Steven Crabill

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