Colorado reports three more plague cases, all had contact with dog that died

In a follow-up to a story last week of a Colorado man and his pet dog who contracted plague, The Colorado Department of Public Health and Environment has identified three additional Colorado residents positive for plague, bringing the total to four cases.

Yersinia pestis bacteria, which was grown on a medium of sheep’s blood agar (SBA) Image/CDC

The investigation of the original case identified three individuals, each of whom had direct contact with the previously reported dog that had died of plague. They all had mild symptoms, were treated with appropriate antibiotics, recovered, and no longer are contagious. The initial patient, who had pneumonic plague, remains hospitalized.

The dog likely was exposed to a prairie dog or rabbit with plague-infected fleas in eastern Adams County.

Tri-County Health Department officials, the Centers for Disease Control and Prevention and the Colorado Department of Public Health and Environment are continuing to work together to investigate these cases and prevent further illnesses. Although person-to-person transmission of plague is extremely rare, individuals who may have been exposed through close contact with the four cases have been identified, and have received antibiotic treatment or are being monitored for symptoms when indicated.

Plague is spread by fleas from rodents, most commonly prairie dogs. Flea samples recently collected from eastern Adams County tested positive for plague bacteria. Tri-County Health Department staff members have gone door-to-door in the area with information about plague and to assess prairie dog populations. People and pets walking in open spaces and trails should avoid contact with prairie dogs, rabbits and other rodents.

Contact your physician if you develop a high fever and other plague symptoms following a fleabite or direct contact with dead rodents, or exposure to a sick cat or dog that may have had contact with plague-infected rodents.

LISTEN: Talking plague and the situation in New Mexico with Dr. Paul Ettestad

Symptoms of plague include a sudden onset of high fever, muscle pain, nausea and vomiting, or a general feeling of being ill. Individuals with pneumonic plague (the lung form) develop fever, headache, weakness, shortness of breath, chest pain and coughing, which can lead to respiratory failure. Pneumonic plague is the most serious form of the disease and is the only form of plague that can be spread from person to person (by infectious droplets from coughing). Although human cases occur infrequently, plague can be severe and potentially life-threatening if not detected and quickly treated with common antibiotics.

Related story: Congo, Madagascar top countries reporting most plague 2000-2009, US reports 57 cases

Plague often is identified when there is an unusual die-off of prairie dogs in an area. When an infected animal dies, the fleas leave the carcass to find another host, thus spreading the disease. Most human plague cases occur when humans are bitten by infected fleas. Less commonly, people are infected by direct contact with blood or tissues from an infected animal or from pets (primarily cats) that become infected and transmit the disease. Since 1957, Colorado has identified 60 cases of human plague, nine (15 percent) of which were fatal. For more infectious disease news and information, visit and “like” the Infectious Disease News Facebook page

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