Editorial Note
RMSF is the most commonly fatal tickborne illness in the United States. Characterized by fever and a macular rash in its early stages, untreated RMSF can result in severe systemic manifestations, including pneumonitis, myocarditis, hepatitis, acute renal failure, encephalitis, gangrene, and death.

An estimated 612 deaths were attributable to RMSF in the United States during 1983-1998, and approximately 12% of reported deaths occurred in children aged <10 years.[4] Family clusters of infection are a well-recognized feature of RMSF because of shared residence and risks for vector exposure.[5]

In its early stages, RMSF can resemble many other infectious and noninfectious conditions and can be difficult to diagnose (Box), even for physicians familiar with the disease.[3,6]

The majority of patients do not have the classic RMSF triad of fever, rash, and history of tick bite on their first visit for medical care; often the rash appears several days after onset of fever and can evolve to become petechial. The absence of known tick bite is common and should not dissuade clinicians from suspecting RMSF.

None of the patients in this report recalled a tick bite before illness onset, although all lived near wooded or grassy areas where ticks might have been present.

Box. (click image to zoom)

The infection can have a rapid course; 50% of RMSF deaths occur within 9 days of illness onset.[1,2] Doxycycline therapy is considered the best treatment for RMSF in both adults and pediatric patients and is most successful when initiated within 5 days of illness onset.[1,7]

Delay of doxycycline therapy can increase the risk for severe or fatal outcomes; treatment should never be delayed pending laboratory confirmation.

Criteria for diagnosis* of a confirmed infection include the presence of a clinically compatible illness, plus at least one of the following:

1) serologic evidence of a significant change (fourfold increase or greater) in antibody titer reactive with R. rickettsii antigens between paired serum specimens, as measured by a standardized assay conducted in a commercial, state, or reference laboratory;

2) demonstration of R. rickettsii antigen by IHC in a clinical specimen such as skin biopsy or other tissue;

3) detection of R. rickettsii DNA by PCR in a clinical specimen, such as whole blood or tissue; or

4) isolation of R. rickettsii from a clinical specimen in cell culture. Probable cases have a clinically compatible illness and serologic evidence of antibodies reactive with R. rickettsii in a single serum sample at a titer considered indicative of current or past infection (cutoff titers are determined by individual laboratories).

At CDC, reciprocal IFA IgG titers of >/=64 are considered to be evidence of current or past infection.

The most effective measures to reduce the risk for RMSF (particularly in children) are to

1) limit exposure to ticks during periods of peak tick activity (i.e., April-September);

2) inspect the head, body, and clothes for ticks thoroughly after being in wooded or grassy areas, especially along the edges of trails, roads, or yards; and

3) remove attached ticks immediately by grasping them with tweezers or forceps close to the skin and pulling gently with steady pressure.

Because rapid laboratory confirmation of RMSF infection is not available, clinicians should consider initiating empiric therapy in patients with a compatible clinical presentation (e.g., fever usually with subsequent development of a macular or petechial rash) and epidemiologic circumstance (e.g., recent recreational or occupational activities during spring and summer months that could have exposed persons to ticks) to reduce morbidity and mortality resulting from delayed diagnosis.[3,6]

As a nationally notifiable disease, all RMSF cases should be reported to state health departments. Additional information about RMSF is available at http://www.cdc.gov/ncidod/dvrd/rmsf/index.htm.

A neighbor of ours nearly died from RMSF last summer. She never saw the tick at all. She was initially misdiagnosed by an infectious disease specialist after onset of rather severe flu-like symptoms. Sent her home, and said "the flu" or "a virus". I find this outrageous in a state where RMSF is very prevalent. NC has the highest rate in the nation. Yet the doctor didn't recognize it at all, and had not even considered it as a differential diagnosis. By the time she finally had to go to the ER, she was very ill. She was ill for weeks, in ICU, with organs shutting down, the whole bit. She is very lucky to be alive, and will have some permanent consequences.

But, one of my points is SHE NEVER SAW THE TICK. And the other point is THE ID DUCK NEVER SUSPECTED RMSF AT ALL.

TICKS ARE EVERYWHERE here, but docs aren't even looking for tick-borne diseases!

I had RMSF years ago and was quite sick. My duck at that time did not correctly diagnose it for a month but told me I was cleared to go back to work after 10 days. Not sure how I got through that period, suppose it helps to be stubborn. A year later at a new Dr. I was ask how many weeks I was hospitalized, turns out my titer was 376. I had been trying to exactly understand what that number meant since the ducks tend to cover for each other.

Thanks for the info. RMSF is definitely not a good time, alot like being in a scary sci fi movie. Thanks again I really appreciate the info since I was delirious at times and never hospitalized it's hard to give accurate info to Drs. I still wondered if they really cleared it up correctly. I also appear to have had menegitis with it which made it very easy for LD to get in brain almost immediately. So if someone has had RMSF and then is bitten by another tick it is really important that the get to Dr or hospital right away and get doxycycline, and do not accept that your just nervous because you had a tick borne illnes before.

My life would be completely different if I had just been a you know what the day I went to the ER to get my last tick removed. Oh by the way the only reason I ever got the diagnoses for RMSF is the a month after getting so sick I was cleaning and found the tick under a tin holding soaps on a shelf in my bathroom and called my Dr. Up until they had not given me the correct meds. Apparently the tick came off after I had washed my hair or blew it dry. Thanks again.
Nancy