Which physical findings are characteristic of Colorado tick fever?

Updated: Aug 05, 2019
  • Author: Shawn J Sethi, DO; Chief Editor: Jeter (Jay) Pritchard Taylor, III, MD  more...
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Physical examination is not particularly helpful for diagnosing Colorado tick fever. 

In 5-15% of patients, a macular, maculopapular or petechial rash is present. Occasionally, a small, red, painless papule (presumably at the bite site) is present. The distribution is often truncal, in contrast to the more acral rash in Rocky Mountain spotted fever. The rash tends to be short lived, which is another difference compared with Rocky Mountain spotted fever. Petechiae occur in rare cases and may be complicated by thrombocytopenia. A palatal enanthema is sometimes present.

Nuchal rigidity is found in 15-20% of cases. Splenomegaly may occur. In severe cases, patients can present with altered sensorium or even coma.

Complications of Colorado tick fever are uncommon. However, cases with neurologic sequelae, including meningitis and meningoencephalitis, are reported, especially in children. [6]

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