Sections View Full Chapter Figures Tables Videos Annotate Full Chapter Figures Tables Videos Supplementary Content +++ Key Features +++ Essentials of Diagnosis ++ Travel in endemic area; tick bite Fever, chills, headache, retro-orbital pain, myalgia Biphasic fever curve Leukopenia early in the illness +++ General Considerations ++ Endemic in the high plains and mountains of the central and northern Rocky Mountains and northern Pacific coast of the United States Reservoir of the virus consists of squirrels and chipmunks Many hundreds of cases occur each year in visitors or laborers entering this region, primarily from May through July +++ Clinical Findings +++ Symptoms and Signs ++ After a 3- to 4-day incubation period (maximum, 14 days), fever begins suddenly together with chills, lethargy, headache, ocular pain, myalgia, abdominal pain, and nausea and vomiting Conjunctivitis may be present A nondistinctive maculopapular rash occurs in 5–10% of patients Illness lasts 7–10 days Half of patients have a biphasic fever curve with several afebrile days in the midst of the illness +++ Differential Diagnosis ++ Enterovirus, measles, or rubella infection may be suspected early in course, especially if rash is present Leptospirosis Borreliosis Tularemia Ehrlichiosis Rocky Mountain spotted fever +++ Diagnosis +++ Laboratory Findings ++ Leukopenia is characteristic early in the illness Platelets are modestly decreased Specific enzyme linked immunosorbent assay (ELISA) testing is available, but 2–3 weeks may elapse before seroconversion Fluorescent antibody staining will detect virus-infected erythrocytes during the illness and for weeks after recovery Reverse transcription polymerase chain reaction (RT-PCR) is positive within the first week of illness +++ Treatment ++ Supportive Do not use analgesics that modify platelet function +++ Outcome +++ Complications ++ Meningoencephalitis occurs in 3–7% of patients Cardiac and pulmonary complications are rare +++ Prevention ++ Avoid endemic areas Use conventional means to avoid tick bite +++ Reference + +Meagher KE, Decker CF: Other tick-borne illnesses: tularemia, Colorado tick fever, tick paralysis. Dis Mon 2012;58(6):370–376 [PubMed: 22608124] . Your Access profile is currently affiliated with '[InstitutionA]' and is in the process of switching affiliations to '[InstitutionB]'. Please click ‘Continue’ to continue the affiliation switch, otherwise click ‘Cancel’ to cancel signing in. Get Free Access Through Your Institution Learn how to see if your library subscribes to McGraw Hill Medical products. Subscribe: Institutional or Individual Sign In Username Error: Please enter User Name Password Error: Please enter Password Forgot Username? Forgot Password? Sign in via OpenAthens Sign in via Shibboleth