Public health officials in Coconino and Navajo counties in Arizona issued a warning after tests found fleas in the northern parts of the state positive for Yersinia pestis. The bacteria is known to have caused the bubonic plague, the infectious disease that killed millions of people during the Middle Ages.
Authorities urged the public to take precautions to reduce their exposure to the disease, which can be transmitted by fleas, rabbits, rodents and predators that prey on these animals.
"An abundance of active prairie dogs doesn't indicate disease is present. However, a sudden die-off of prairie dogs and rodents, may be an indicator of plague. Persons noticing a sudden die-off of rodents or rabbits are urged to contact the Navajo County Health Department," reads Navajo County Health Department's public advice.
The disease can spread when humans and other animals get bitten by an infected flea. It can also be transmitted by direct contact with an infected animal. The plague can be transmitted through body fluids such as respiratory droplets so it is possible to contract the bacteria when handling tissue or fluids of animals with the illness. The disease may spread throughout the bloodstream (septicemic), or may affect the lungs (pneumonic).
"Out of the human cases with bubonic plague, around 10% develop pneumonic plague, meaning the infection continuing to spread in the organism gets into their lungs," WHO said. "People in close contact with pneumonic cases can be directly contaminated by respiratory droplets, such as from coughing."
For those who have concerns that they may have been exposed to the illness, the symptoms of plague in humans typically appear between two and six days after exposure. Symptoms include chills, fever, weakness, headache, muscle pain and swollen glands in the limbs, armpits or groins.
Disease That Killed Millions Centuries Ago Persists
The disease was once known as the Black Death likely because of the dark patches caused by bleeding under the skin. It swept through Europe 700 years ago and left about 25 million people dead. The number is equivalent to a third of Europe's population. It also killed millions in Hong Kong and China.
Even centuries later, the disease periodically emerges in some parts of the globe albeit at a relatively minor level. The plague can persist in rodent populations for a long time sans affecting humans but there is the possibility it can re-emerge in human population.
In 2015, WHO recorded 320 cases of plague worldwide. Of these, 77 resulted in death. The typical number of human plague cases in the United States, on the other hand, is 17 per year. The disease is curable with antibiotics if diagnosed and treated early.