A Montezuma County cat has tested positive for bubonic plague, prompting health officials to urge residents and visitors to take precautions against the potentially fatal disease.

The cat, from a rural area northeast of Cortez, was brought to a local veterinary clinic after it injured a child. Whether the wound was a bite or a scratch could not be determined, and the child has developed neither plague symptoms nor a positive culture.

Tests performed on the cat indicated that it had the disease. A blood sample from the cat has been sent to the Colorado Department of Public Health and Environment for confirmation of the diagnosis.

Plague is caused by a bacterium, Yersinia pestis, carried by fleas that infest wild animals, including rats, prairie dogs, rabbits and squirrels. It is transmitted to humans by flea bites experienced when a person is walking through a rodent-infested area, and through direct contact with infected animals. Fleas are aggressive parasites and will readily bite other animals, particularly if their natural hosts are killed.

Domestic pets can also contract plague by eating infected animals or by being bitten by fleas.

"Pets come in contact with the fleas by nosing around rodent holes, or a pet that hunts may contract the disease by killing and eating an infected animal," explained Cathy Allen, a veterinarian with Cedarwood Animal Clinic, who said that cases of plague in cats are not rare.

"This is an endemic area," Allen said. "We see it every year."

Plague, a bacterial disease which killed 28 million Europeans during the Middle Ages, was introduced to North America by rat-infested ships. Because it cannot be effectively eliminated from the animal population, plague is always a threat. The incidence of human cases tends to rise and fall in cycles lasting several years.

Cats and dogs may carry fleas home to their owners, or may serve as a direct source of infection through body fluids. Animals which groom themselves and kill fleas with their teeth are at risk for a tonsillar form of plague. Plague-infected cats exhibit symptoms similar to those of humans; dogs generally do not develop the illness but may still host infected fleas.

Flea control is the best way of preventing the spread of plague from animals to humans, Allen said.

In recent years, topical products have been developed that, when applied to the back of a pet, will protect against fleas for one to three months. Such products are available from local veterinarians.

The incubation period of plague in humans is usually two to six days between the time of exposure and the appearance of symptoms. Typical symptoms include sudden onset of fever and chills, severe headache, muscle aches, nausea, vomiting and a general feeling of illness. Extreme pain and swelling in a lymph node draining the infection site is a sign of bubonic plague.

Other forms of the illness include septicemic plague, with no infected lymph node, or bubo, developing, and pneumonic plague. Pneumonic plague can be spread by inhalation of droplets expelled by another human or animal with plague pneumonia.