Be alert to the possibility of Rocky Mountain spotted fever in endemic areas when any of four common symptoms present, especially in spring or summer, results of a new study suggest.
Common symptoms are fever, rash, nausea and/or vomiting, and headache.
Moreover, a medical outpatient visit early in the course of illness is significantly associated with delay in therapy.
Those are key findings from a review of 92 children with laboratory-confirmed Rocky Mountain spotted fever who were treated at six medical centers in the South Central United States between Jan. 1, 1990, and Dec. 31, 2002.
Diagnosis of the condition “should be considered in children in the first few days of their illness who have any single compatible finding especially during the spring and summer,” wrote the researchers, who were led by Dr. Steven C. Buckingham of the department of pediatrics at the University of Tennessee, Memphis. “Children generally improve markedly after starting antirickettsial therapy—as demonstrated by, on average, defervescence within 2 days and hospital discharge within 5 days. Those outcomes are certainly worth achieving.”
He and his associates with the Tick-Borne Infections in Children Study Group reviewed the demographic, clinical, and laboratory data from the medical charts of 92 children with the illness (J. Pediatr. 2007;150:180–4). Their mean age was 6 years and most (92%) were white.
The researchers reported that children presented to the respective medical centers after a median of 6 days of symptoms. The four most common symptoms were fever (98%), rash, (97%), nausea and/or vomiting (73%), and headache (61%); 49% of children reported antecedent tick bites.
Blood platelet counts were below 150,000/mm
Most (86%) sought medical care before hospital admission yet only four patients received antirickettsial therapy during that time. Delays in treatment “occurred not because patients … failed to seek medical attention, but because their treating clinicians failed to consider [the diagnosis],” the researchers wrote. “Such diagnostic misadventures are understandable given the nonspecificity of the usual presenting clinical and laboratory features.”
Three children died and 13 had neurologic deficits on discharge, including speech and/or swallowing dysfunction (6 patients), global encephalopathy (4), ataxia or other gait disturbances (4), and cortical blindness (1). Follow-up data were available for only five: One had weakness that resolved by 10 days after discharge; the other four had persistent abnormalities reported from 2 months to 4 years after discharge, the researchers said.
Antirickettsial therapy included doxycycline alone, chloramphenicol alone, tetracycline alone, doxycycline plus chloramphenicol, and tetracycline plus chloramphenicol.
Since 1994, doxycycline alone has been the sole treatment used.
The study was limited by the fact that only medical records were analyzed and that serologic testing for the disease is an imperfect science.