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A ProMED-mail post
ProMED-mail is a program of the
International Society for Infectious Diseases
Date: 11 Jul 20099
Source: National Park Traverl.com [edited]
Officials have confirmed the presence of sylvatic plague and
tularemia in Badlands National Park. That's bad news for the park's
prairie dogs and black-footed ferrets, but visitors should be OK if
they use common sense safety precautions.
Sylvatic plague, which was 1st detected in South Dakota in 2004,
turned up last year [2008] in the prairie dog population of the
Conata Basin just south of Badlands National Park. Since fleas spread
plague from infected animals to healthy ones (and occasionally to
humans as well), officials ordered a flea suppression campaign that
entailed applying insecticides to prairie dog colonies over an area
of about 11 000 acres. In addition, black-footed ferrets were
captured and given plague vaccinations. It was fervently hoped that
these measures would keep the disease from spreading to Badlands
National Park, which not only harbors many thousands of prairie dogs
but also a small and struggling population of endangered black-footed
ferrets that mainly feed on prairie dogs.
Alas, about a week ago, wildlife biologists confirmed that the
prairie dog population in the Sage Creek Wilderness Area of the park
is being assaulted by sylvatic plague. Tularemia (rabbit fever) has
also been detected in one of the park's prairie dog colonies. Both
diseases sicken and kill prairie dogs, so this disease outbreak has
the potential to decimate the park's prairie dog population and
perhaps undo much of the effort that's been invested in
reestablishing black-footed ferrets there.
Although few people in the U.S. have ever been infected by plague or
tularemia, both diseases can be transmitted to humans and should be
considered potentially dangerous. Park officials are advising
visitors to take these common sense safety precautions to minimize
the likelihood of infection:
- Be aware that potentially dangerous diseases can be transmitted to
humans by way of ticks or bites and scratches, urine-contaminated
water, and the inhaling of infectious aerosols.
- Apply DEET insect repellant to clothing and skin to avoid bites
from fleas and ticks.
- Avoid handling sick or dead animals in the park.
- Do not allow pets to wander into prairie dog colonies where they
may come into contact with disease-carrying fleas.
- See a doctor if you think that you may have been exposed to plague
or tularemia.
--
Communicated by:
ProMED-mail Rapporteur Brent Barrett
[These are diseases spread by ground squirrels and other wild
rodents, frequently in the western portion of the United States.
"Sylvatic" means pertaining to the woods (sylvan). These are diseases
spread by wild rodents, which serve as a reservoir for humans. In the
western part of the US, they are often spread by prairie dogs, ground
squirrels and other small ground rodents. These diseases can happen
almost anywhere, but we frequently see the problems in the western
region of the US.
Plague results from infection by _Yersinia pestis_, a non-motile,
facultatively intracellular, Gram negative rod (family _Enterobacteriaceae_).
Plague is usually spread between rodents or humans by the bites of
infected fleas. Vectors include a variety of rodent fleas,
particularly the oriental rat flea (_Xenopsylla Cheopis_). In the
U.S., the most common vector is _Oropsylla Montana_, a flea often
found on California ground squirrels, rock squirrels, and sometimes
other rodents including prairie dogs. Human fleas (_Pulex irritans)_
may also carry _Y. pestis_. _Y. pestis_ is also present in the
tissues and body fluids of infected animals; these bacteria can be
transmitted directly through mucous membranes and broken skin.
Aerosols from people or animals with the pneumonic form are
infectious, and animals may transmit bacteria in bites. Carnivores
often become infected when they eat diseased rodents.
Prairie dogs are considered to be sensitive indicators of plague and tularemia.
Tularemia results from infection by _Francisella tularensis_
(formerly known as _Pasteurella tularensis_), a Gram negative,
non-motile coccobacillus. Two subspecies exist: _F. tularensis
tularensis_ (also known as Jellison type A) and _F. tularensis
holarctica_ (Jellison type B). _F. tularensis tularensis_ is found in
lagomorphs in North America and is highly virulent for humans and
domestic rabbits; _F. tularensis holarctica_ is less virulent and
occurs in beavers, muskrats and voles in North America and in hares
and small rodents in Eurasia.
_F. tularensis_ can be transmitted by ingestion, inhalation,
arthropod-borne transfer or direct contact through the skin and
mucous membranes. Organisms are found in the blood and tissues of
infected animals and can survive for long periods on fomites
including food and water. Aquatic animals may develop tularemia after
being immersed in contaminated water. Carnivores sometimes become
infected after ingesting a contaminated carcass. Vectors for _F.
tularensis tularensis_ include ticks (including _Dermacentor
andersoni_, _D. variabilis_ and _Amblyomma americanum_) and biting
flies (particularly deerflies). _F. tularensis holarctica_ is also
transmitted by mosquitoes in Russia. Rarely, the organism is spread
by animal bites.
_F. tularensis_ can survive for long periods in arthropod vectors and
in the environment. Individual flies may carry the organism for 2
weeks and ticks throughout their lifetimes. Viable bacteria can also
be found for weeks to months in the carcasses and hides of infected
animals and in fomites including grain dust, straw, water, soil and
bedbugs. This organism is highly resistant to freezing; live
organisms have been found after 3 years in rabbit meat stored at -15 C.
Portions of this comment have been extracted from:
[see also:
Plague, fatal - USA (02): (NM) risk, prevention 20090611.2153
Plague, fatal - USA: (NM) bubonic 20090605.2080
Plague, rabbit - USA (NM) 20090415.1435
Tularemia, feline, canine - USA (SD) 20090711.2481
Tularemia, rabbits - USA (02): (NM) 20090417.1458
Tularemia, rabbits - USA (NM) 20090415.1429
2008
----
Plague, human, prairie dogs - USA: (AZ) 20081012.3229
Plague, bubonic - USA: (CT ex WY) 20080827.2672
Plague, wildlife - USA: (CO) rabbit 20080727.2289
Plague, prairie dogs, ferrets - USA: (SD)(02) 20080722.2213
Plague, prairie dog, ferrets - USA: (SD) 20080708.2082
Plague, feline - USA (WY): mountain lion 20080522.1694
Plague, prairie dogs - USA: (CO), susp., RFI 20080506.1552
Plague, human, feline - USA (NM): early season cases 20080127.0340
Tularemia, human, feline - USA: (NV) 20080825.2652
Tularemia, pneumonic - USA: (NYC) 20080612.1863]
....................................................tg/msp/dk
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