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Disease Name: Rocky Mountain Spotted Fever

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Please review the Idaho Reportable Disease Rules (IDAPA 16.02.10) for the most up-to-date information.

Tickborne Diseases of the United States: http://www.cdc.gov/ticks/tickbornediseases/rmsf.html

Overview / Case Definition

Spotted fever rickettsioses are a group of tickborne infections caused by some members of the genus Rickettsia. Rocky Mountain spotted fever (RMSF) is an illness caused by Rickettsia rickettsii, a bacterial pathogen transmitted to humans through contact with ticks. Dermacentor species of ticks are most commonly associated with infection, including Dermacentor variabilis (the American dog tick), Dermacentor andersoni (the Rocky Mountain wood tick), and more recently Rhipicephalus sanguineus (the brown dog tick).

Disease onset averages one week following a tick bite. Age-specific illness is highest for children and older adults. Illness is characterized by acute onset of fever, and may be accompanied by headache, malaise, myalgia, nausea/vomiting, or neurologic signs; a macular or maculopapular rash appears 4-7 days following onset in many (~80%) patients, often present on the palms and soles. RMSF may be fatal in as many as 20% of untreated cases, and severe, fulminant disease can occur.

In addition to RMSF, human illness associated with other spotted fever group Rickettsia species, including infection with Rickettsia parkeri (associated with Amblyomma maculatum ticks), has also been reported. In these patients, clinical presentation appears similar to, but may be milder than, RMSF; the presence of an eschar at the site of tick attachment has been reported for some other spotted fever rickettsioses.




Within 3 working days

Reportable by Healthcare and Labs:

Reportable by Food Service Facility:

Suspect Reportable:

Reporting Timeframe: Within 3 working days

Diagnosis / Testing

The organism in the acute phase of illness is best detected by polymerase chain reaction (PCR) and immunohistochemical methods (IHC) in skin biopsy specimens, and occasionally by PCR in appropriate whole blood specimens taken during the first week of illness, prior to antibiotic treatment. Serology can also be employed for detection, however an antibody response may not be detectable in initial samples, and paired acute and convalescent samples are essential for confirmation.


Additional Information

Tickborne Diseases of the United States: http://www.cdc.gov/ticks/tickbornediseases/rmsf.html

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