Health officials in Colorado have confirmed a rare case of human plague, a potentially life-threatening disease transmitted from infected rodents.

"The Pueblo Department of Public Health and Environment, in collaboration with the Colorado Department of Public Health and Environment, is investigating a human case of plague based on preliminary test results," Pueblo County officials said in a news release.

Although plague was responsible for massive pandemics and millions of deaths in Europe during the Middle Ages, it is now a rare infection, with only a few thousand cases reported worldwide. In the U.S., the disease affects up to 7 people annually.

Plague is caused by Yersinia pestis bacterium which naturally occurs among wild rodents and other animals. Humans may contract the infection from bite of an infected rodent flea or while handling an infected animal. The bacterium can also spread through direct contact with contaminated tissues or fluids of infected animals. These are the most common forms of transmission for bubonic and septicemic types of plague.

In rare instances, a form of plague called pneumonic plague can be transmitted through respiratory droplets from an infected person or animal, but this requires direct and close contact with the individual.

The signs of plague vary with the type of plague. For patients with bubonic plague, common symptoms include fever, headache, chills, weakness, and swollen, painful lymph nodes (buboes). The symptoms typically begin within 2 to 8 days after the bite of an infected flea.

If untreated with antibiotics, the bacteria can spread to other parts of the body and can lead to septicemic plague. Septicemic plague may also occur as the first symptom of flea bites or handling an infected animal. The symptoms include fever, chills, extreme weakness, abdominal pain, shock, and bleeding into the skin and other organs. Skin and tissues, especially on fingers, toes, and the nose, may turn black and die.

Pneumonic plague can result from untreated bubonic or septicemic plague, or by inhaling infectious droplets. Symptoms include fever, headache, weakness, and pneumonia with shortness of breath, chest pain, cough, and sometimes bloody or watery mucus. It is the most serious form and the only one that can spread person-to-person.

To reduce the risk of plague, it is recommended to avoid flea bites, and direct contact with infected body fluids, tissues, and carcasses. Officials advise using insect repellent containing 20-30 percent DEET to prevent flea bites. Not allowing pets to roam in areas known for rodents and regularly treating them for fleas can prevent infection in them. Using standard precautions when handling potentially infected patients and collecting specimens can also reduce the transmission risk.

Although a serious infection, early diagnosis allows for effective treatment with commonly available antibiotics, significantly reducing the risk of complications or death. Close contacts of severely ill pneumonic plague patients may also receive preventive antibiotic therapy after evaluation.

"If you develop symptoms of plague, see a health care provider immediately. Plague can be treated successfully with antibiotics, but an infected person must be treated promptly to avoid serious complications or death," said Alicia Solis from Pueblo Department of Public Health and Environment.

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