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Commentary
Prairie Dog: Cuddly Pet or
Trojan Horse?
Abdu F. Azad*
*University of Maryland School of Medicine, Baltimore, Maryland, USA
Suggested citation
for this article:
Azad AF. Prairie dog: cuddly pet or Trojan horse? Emerg Infect Dis [serial
online] 2004 Mar [date cited]. Available from: http://www.cdc.gov/ncidod/EID/vol10no3/04-0045.htm
In this issue of Emerging Infectious Diseases, two articles analyze tularemia
outbreaks, and one examines the pathologic features of monkeypox in commercially
traded prairie dogs. While the prairie dog–associated tularemia outbreak
and the first U.S. monkeypox outbreak highlight health risks to humans
of the unregulated trade of wild-caught animals, they also raise broader
issues. Exotic animal import and export have altered the composition of
native fauna and flora throughout the world and have been associated with
disease outbreaks. In addition, translocation of animals in some circumstances
has provided the opportunity for pathogens to jump species and become
established in native animal populations. Examples abound of intentionally
or accidentally imported exotic species introducing new pathogens (e.g.,
rats introducing Yersinia pestis, the etiologic agent of plague,
to the western United States) and allowing them to become established
in native animal populations.
Avashia et al. (1) and Petersen et al. (2),
analyzing the tularemia outbreak in commercially traded prairie dogs,
underscore the difficulty of identifying existing infection in wild-caught
animals, particularly by commercial collectors and distributors who trap
prairie dogs from disease-endemic foci. The outbreak was predictable,
considering the conditions in which the animals were kept. In retrospect,
the prairie dog–associated monkeypox outbreak highlights the speed with
which exotic rodent species, transported worldwide, allow virulent pathogens
to jump species and be transmitted to humans. Often, infection with these
pathogens is fatal for recipient animals, as is the case in prairie dogs
infected with Y. pestis or Francisella tularensis (the etiologic
agent of tularemia). The infected animals can also become “silent” carriers
and serve as a new reservoir for the introduced pathogen. The overall
outcome of a pathogen’s jumping species often remains unpredictable. Guarner
et al. (3) investigated the pathologic features of monkeypox
in prairie dogs to identify the route of viral transmission to humans.
They found that viral transmission could occur through both respiratory
and direct mucocutaneous exposure. In addition, prairie dogs may be an
excellent model for assessing monkeypox viral transmission, pathogenesis,
and new vaccines and treatments.
Recent incidents involving plague, tularemia, and monkeypox transmission
to humans by pet prairie dogs are a wake-up call for better surveillance
of wild-caught animals before they are sold internationally and imported
into the United States. Relying on visual inspection to select healthy
animals is virtually impossible, since wild-caught animals often do not
exhibit signs of overt disease and may not appear sick during the early
stages of infection with Y. pestis or F. tularensis. Prairie
dog–associated monkeypox and tularemia, as discussed in Avashia et al.,
Petersen et al., and Guarner et al. (1–3), highlight
the need for more research, public education, regulatory guidelines for
exotic animal husbandry practices, and possibly a ban on the sale of wild-caught
animals. Although the examples in this issue relate to prairie dogs, they
may well serve as harbingers of other emerging infections. In introducing
seemingly harmless furry friends, the trade of exotic pets brings together
species that have never encountered one another in nature, with unpredictable
and sometimes tragic results.
References
- Avashia SB, Petersen JM, Lindley CM, Schriefer ME,
Gage KL, Cetron M, et al. Prairie dog–to-human tularemia transmission,
Texas, 2002. Emerg Infect Dis 2004;10:483–6.
- Petersen JM, Schriefer ME, Carter LG, Zhou Y, Sealy T, Bawiec D, et
al. Laboratory analysis of tularemia in wild trapped, commercially traded
prairie dogs, Texas, 2002. Emerg Infect Dis 2004;10:419–25.
- Guarner J, Johnson BJ, Paddock CD, Shieh W-J, Goldsmith CS, Reynolds
MG, et al. Monkeypox transmission and pathogenesis in prairie dogs.
Emerg Infect Dis 2004;10:426–31.
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