Plague has been identified as a disease of concern to human, wildlife and domestic
animal populations within the United States. It is also considered a
A" disease by the Department of Homeland Security, meaning
it could potentially be used as a bioterrorist agent.
In the US, plague is almost exclusively restricted to the western half
of the country (west of the 102nd meridian).
This infectious disease is caused by the bacterium Yersinia pestis
and is primarily vectored by fleas.
Plague mostly affects, and is reservoired within, rodent populations
such as chipmunks, ground squirrels and prairie dogs, but can also affect
other mammals, such as carnivores and scavengers that feed on rodents.
Plague represents a health and safety threat to humans, especially in
places where humans and rodents interface. There are currently about
a dozen human plague cases reported each year.
Members of the cat family, Felidae, such as bobcats, mountain lions
and domestic cats are particularly susceptible to plague while the Canidae
(dog) family, including coyotes, wolves and domestic dogs, tend to be
fairly resistant to plague. Because cats are susceptible to plague and
tend to develop the highly-contagious form of the disease (pneumonic
plague), they can represent a health threat to people who come in contact
with them (ie, sportsmen, wildlife personnel & pet owners). While
canids do not tend to develop an active form of plague, they do readily
develop antibodies to plague when they come in contact with the disease
through scavenging or predation of infected rodents. Testing the canid’s
blood for the presence of these antibodies is a convenient and efficient
method of monitoring the area’s rodent population for plague activity.
NWDP biologists work closely with other WS personnel who conduct wildlife
damage management (WDM) activities to protect human health, agriculture
and natural resources. Collecting samples from coyotes taken during
WDM activities to test for the presence of plague antibodies is useful
because the coyotes make frequent contact with the infected rodents
through predation and scavenging. If contact is made with an infected
rodent, the coyote develops a titer (evidence of an immune response),
which indicates that plague is likely present in the area.
When the presence of plague is detected through lab diagnostic testing,
this evidence is shared with local health officials, both human and
veterinarian. Once alerted to the presence of the disease in their area,
health personnel can be on the look-out for patients exhibiting plague's
flu-like symptoms (fever, chills, swollen lymph nodes, etc.). Plague
symptoms so closely resemble other common diseases that physicians and
verterinarians who have not been alerted that plague is active in their
area may fail to consider plague in their diagnostic testing. Because
plague is generally not a commonly-encountered disease, health providers
who are unaware of its presence are likely to only test for the more
commonly-encountered illnesses, thus delaying the true diagnosis. When
detected early, plague infections can be readily treated with antibiotic
drugs with excellent results. A delay in the diagnosis, even for a short
period, can make treatment much more difficult and could lead to fatal
Plague Surveillance Updates
Plague Surveillance Update Volume 1, Issue 1, October 2010
NWDP Sylvatic Plague Surveillance Update May 2011
More information on plague:
Disease Control- Plague
3 Background, Biological Agents (Homeland Security Factsheet)
Thomas Gidlewski, DVM
4101 Laporte Ave
Fort Collins, CO 805021