Epidemiologic Notes and Reports Winter Plague -- Colorado, Washington, Texas, 1983-1984

Three human plague cases have been reported to and confirmed by CDC during the 1983-1984 winter season. The patients, all adult males, acquired their infections by direct contact with infected animal tissues. Plague or tularemia was suspected early in all three cases. They were treated with appropriate antibiotics and recovered uneventfully. Brief case reports follow.

Case 1: A 32-year-old gas-well service contractor in Rangely, Rio Blanco County, Colorado, experienced onset of illness with fever, malaise, and painful axillary swelling on December 11, 1983; he was hospitalized on December 12. Two blood cultures obtained on admission grew organisms subsequently identified as Yersinia pestis. The patient was treated with streptomycin and progressively improved. Sera drawn from the patient on December 12 and December 19 had plague antibody titers of less than 4 and 64, respectively.

Interviews with the patient revealed that he had shot, skinned, and dressed a cottontail rabbit on December 8 or December 9 in an area about 25 miles south of Rangely. During follow-up studies of this case, 12 cottontail rabbits from this area and 29 pools of 506 fleas from them were collected, none of which yielded evidence of plague infection.

This is the second human plague infection reported from Rio Blanco County; the first occurred in a 60-year-old man in June 1967.

Case 2: A 29-year-old male resident of Yakima County, Washington, who is a professional hunter/trapper, suffered onset of illness on January 11, 1984. Clinical findings on hospitalization on January 12 included fever and bilateral axillary pain and swelling. Based on his symptoms and on a history of repeated animal contact, the patient's illness was diagnosed as tularemia. He was treated with tetracycline and recovered. Blood cultures taken on admission grew organisms subsequently identified as Y. pestis. Paired sera drawn January 12 and February 7 showed plague antibody titers of less than 4 and 32, respectively.

The patient's exposure to infection probably occurred January 7 or January 8, when he skinned several coyotes and bobcats. He remembered cutting his arm while doing so. Long bones from the carcasses of three coyotes and three bobcats the patient had skinned were recovered from their disposal site and submitted for bacteriologic testing. Y. pestis was recovered from two of the bobcat specimens; Pasteurella multocida, a common, sometimes pathogenic, bacterial resident of mammalian respiratory tracts, was also recovered from one of the plague-positive bobcats.

This case is the first human plague infection reported from Yakima County and the first human case in Washington since 1913. The eight previous indigenous Washington cases, seven in 1907 and one in 1913, all occurred in Seattle, King County.

Case 3: A 48-year-old Winkler County, Texas, man had hunted, skinned, and dressed cottontail rabbits in the Wink, Texas, area on January 14, 1984. He experienced onset of illness, including fever, chills, and axillary soreness on January 16. He sought medical attention and was hospitalized on January 18. Blood cultures were obtained, and the patient was treated with antibiotics, including tetracycline. He gradually improved and was afebrile on January 22, when organisms recovered from an admission blood culture were tentatively identified as Y. pestis. This culture was destroyed, and no confirmatory tests were performed. Paired sera drawn January 24 and February 2 demonstrated a fourfold decrease in titer to Y. pestis--32 and 8, respectively--confirming the diagnosis of plague.

The patient's hunting companion, who had similar exposure, became ill with a cough and fever on January 20. Plague was considered but eventually ruled out by serologic testing.

Fifteen rabbit carcasses processed and frozen by the two men were available for bacteriologic studies. Y. pestis was recovered from three of these carcasses. This is the first human plague infection reported from Winkler County and the second indigenous human plague case in Texas since 1920. The last human case occurred in a 22-year-old male resident of Ector County, who died in January 1982. Ector County adjoins the eastern boundary of Winkler County.

None of the sera from the three patients had measurable antibody titers to the tularemia organism. None of the three patients developed secondary plague pneumonia, and no concurrent cases occurred among contacts of the patients. Reported by M Sindler, MD, WH Brady, MD, V McElvane, Rangely District Hospital, Rangely, JK Emerson, DVM, SW Ferguson, PhD, State Epidemiologist, Colorado Dept of Health; J Allard, PhD, M McDowell, PhD, L Baum, JM Kobayashi, MD, State Epidemiologist, Washington State Dept of Social and Health Svcs; KD Heath, MD, GM Caspit, MD, Kermit, MG Gollapudi, MD, Midland, WW Rosser, DVM, CR Allen, MD, Public Health Regions 2 and 12, CE Alexander, MD, Acting State Epidemiologist, Texas Dept of Health; Plague Br, Div of Vector-Borne Viral Diseases, Center for Infectious Diseases, CDC.

Editorial Note

Editorial Note: From 1956 to 1983, 231 persons in the United States were reported ill with plague, and an additional two persons have had plague as of March 1, 1984. The majority of these persons experienced onset from April through September. "Off-season" plague occurs during rabbit-hunting season in many states (October-February) primarily among male rabbit hunters (Table 1). Of off-season cases, 26 of 30 occurred in males (24 of hunting age, i.e., 12 years of age and older), and 15 were proven or circumstantially associated with direct contact with rabbits or hares. Incriminated sources for other off-season cases include direct contact with tissues of bobcats (three cases), coyotes (1), Abert's squirrels (1), or domestic cats (2). 0ne plague patient, associated with a sick domestic cat, developed primary plague pneumonia. Sources of infection for eight cases were not determined, but four were considered possibly due to flea bites, the usual mode of transmission during warmer months.

Ten of the 30 cases occurred in nine areas that had never before reported human plague and constitute the only human infections recorded for these counties. For two patients, the places of exposure were far removed from the location where they had onset of illness. A Eugene, Oregon, resident hunted rabbits in central Wyoming and became ill in Ontario, Oregon, enroute home. A Klamath County, Oregon, man, most likely exposed at or near home, traveled to Los Angeles, California, before onset of his fatal illness. These data emphasize the continuing need for physicians and laboratory personnel at any time and in any place to be alert to the possibility of plague infection in a patient with fever, lymphadenopathy, and a suggestive epidemiologic history (i.e., wild-animal exposure in the western states).

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