On Friday, Benton-Franklin Health District officials announced that a local resident was being tested for a possible case of pneumonic plague.

This image depicts a magnified view of an oriental rat flea, Xenopsylla cheopis. Image/CDC
This image depicts a magnified view of an oriental rat flea, Xenopsylla cheopis. Image/CDC

On Saturday, health officials said tests performed at the Washington State Department of Health were negative.

Plague occurs naturally in the western United States; the last case in Washington State was in 1984. The plague bacterium (Yersinia pestis) is transmitted by fleas and cycles naturally among wild rodents. Plague can also infect humans and their pets. Plague can be treated successfully with antibiotics, but an infected person must be treated promptly. Anyone who has been exposed to the illness can be treated with antibiotics before developing symptoms.

Plague is most often transmitted through bites of infected fleas. It can also be contracted by touching or skinning infected animals (coyotes, squirrels, rats, prairie dogs, and rabbits) or inhaling droplets from the cough of an infected person or animal (especially sick cats). The last reported human-to-human transmission in the US occurred in the 1920s.

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