Why it’s a Threat
is a disease caused by Yersinia pestis,
a bacterium found in rodents and their fleas.
Human plague occurs in the western United States
with an average of 5 to 15 cases each year.
Globally, the World Health Organization reports
1,000 to 3,000 cases of plague every year.
The most common form of the disease, bubonic plague,
is characterized by a swollen and very tender
lymph node called a "bubo". Less
common forms include pneumonic plague, characterized
by high fever, cough, bloody sputum and difficulty
in breathing and septicemic plague, characterized
by fever and gastrointestinal symptoms. Y.
pestis is considered a potential biological
weapon and is classified as a Category A agent.
Gram-negative bacteria, coccobacillus, approximately
0.5 µm wide and 1.5 microns long, exists as
single organism or in short chains; nonmotile.
Y. pestis is most commonly transmitted
to humans by the bite of an infected flea. Y.
pestis can also be transmitted by direct handling
of tissue or body fluids of a plague-infected animal
or by inhaling respiratory droplets expelled by a
person or animal with pneumonic disease.
Eliminating food and shelter for rodents in and
around homes, work places, and recreation areas by
making buildings rodent-proof, and by removing brush,
rock piles, junk, and food sources (such as pet food),
from properties. Treatment of pets (dogs and cats)
for flea control, once each week, is recommended.
Plague can be effectively treated with appropriate
antibiotics; however, about 14% (1 in 7) of all plague
cases in the United States are fatal. Deaths typically
result from delays in seeking treatment or misdiagnosis.
About 50-60% of bubonic plague patients who fail
to receive any antibiotic treatment die. Untreated
septicemic or pneumonic plague is almost always fatal.