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March 1963

Thrombocytopenia in Colorado Tick Fever

Author Affiliations


Clinical Fellow in Hematology.; From the Department of Medicine, University of Utah College of Medicine.

Arch Intern Med. 1963;111(3):307-308. doi:10.1001/archinte.1963.03620270033005

Thrombocytopenia has been reported as occurring during the course of a number of infectious diseases,1 including those caused by bacteria, viruses, and rickettsia. The purpose of this report is to record the first documented occurrence of thrombocytopenia in association with Colorado tick fever, a ticktransmitted viral disease indigenous to the Rocky Mountain area of the Western United States.

Report of a Case  A 59-year-old white male was working during the summer of 1961 in the mountains of Utah at an elevation of 8,000 ft. On Aug. 11, he was bitten on the right arm by a tick. For the next 4 days, he was asymptomatic. On Aug. 15, he noted the sudden onset of fever, pleuritic chest pain, malaise, retroorbital headache, myalgia, and arthralgia. He immediately went to bed and took some acetylsalicylic acid. The next 3 days the symptoms persisted, and, in addition, he had several nosebleeds. On

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