The case was flagged last Friday from preliminary test results, and the potential source of the infection is still under investigation, the Pueblo Department of Public Health and Environment in the state of Colorado said.
The plague is an infectious disease caused by bacterium, “Yersinia pestis”, transmitted by fleas.
Although it is best known for The Black Death, an outbreak that killed millions of Europeans during the Middle Ages, the bacteria circulates naturally among wild rodents and rarely infects humans today, according to the US Centers for Disease Control and Prevention (CDC).
Plague is transmitted to humans through bites from infected fleas, contact with infected animals or inhaling droplets from the cough of an infected person or animal.
Anyone who develops symptoms of plague should get medical attention immediately, the CDC says.
Typical symptoms include sudden fever and chills, severe headache, muscle aches, nausea, vomiting and, commonly, swollen lymph nodes with pain.
“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 the Pueblo Department of Public Health and Environment.
“We advise all individuals to protect themselves and their pets from plague,” the department says.
One way to avoid infection is to eliminate places where wild rodents can exist around humans such as brush, rock piles, trash and piles of lumber around homes, garages, sheds and recreation areas, according to the department.
Taking precautions around pets can also reduce risk of transmission. The department suggests treating dogs and cats for fleas, keeping pet food in rodent-proof containers and not letting pets roam in rodent areas or sleep in bed with you.
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From 1970 to 2022, there were 67 reported cases of plague in Colorado, according to the CDC. Worldwide, 3248 human plague cases were reported from 2010 to 2015, most commonly in the Democratic Republic of Congo, Madagascar and Peru, the World Health Organisation found.
“A plague vaccine is no longer available in the United States,” the CDC says. “New plague vaccines are in development but are not expected to be commercially available in the immediate future.”