Emerging Infectious Diseases (Dec 2016)

Investigation of and Response to 2 Plague Cases, Yosemite National Park, California, USA, 2015

  • Mary Danforth,
  • Mark Novak,
  • Jeannine Petersen,
  • Paul S. Mead,
  • Luke Kingry,
  • Matthew Weinburke,
  • Danielle Buttke,
  • Gregory Hacker,
  • James Tucker,
  • Michael Niemela,
  • Bryan Jackson,
  • Kerry Padgett,
  • Kelly Liebman,
  • Duc Vugia,
  • Vicki L. Kramer

DOI
https://doi.org/10.3201/eid2212.160560
Journal volume & issue
Vol. 22, no. 12
pp. 2045 – 2053

Abstract

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In August 2015, plague was diagnosed for 2 persons who had visited Yosemite National Park in California, USA. One case was septicemic and the other bubonic. Subsequent environmental investigation identified probable locations of exposure for each patient and evidence of epizootic plague in other areas of the park. Transmission of Yersinia pestis was detected by testing rodent serum, fleas, and rodent carcasses. The environmental investigation and whole-genome multilocus sequence typing of Y. pestis isolates from the patients and environmental samples indicated that the patients had been exposed in different locations and that at least 2 distinct strains of Y. pestis were circulating among vector–host populations in the area. Public education efforts and insecticide applications in select areas to control rodent fleas probably reduced the risk for plague transmission to park visitors and staff.

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