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

PLAGUE; YERSINIA pestis; ISOLATION of biotechnological microorganisms; PUBLIC health; INFECTIOUS disease transmission; ALLELES; ANIMAL experimentation; DISEASE vectors; COMPARATIVE studies; EPIDEMIOLOGICAL research; FLEAS; GENOMES; GRAM-negative bacteria; RESEARCH methodology; MEDICAL cooperation; GENETIC mutation; RESEARCH; EVALUATION research; SEQUENCE analysis; DIAGNOSIS

UNITED States; YOSEMITE National Park (Calif.); CALIFORNIA

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. [ABSTRACT FROM AUTHOR]