Spotting Rocky Mountain Spotted Fever in Children

Clinical and Laboratory Features, Hospital Course, and Outcome of Rocky Mountain Spotted Fever in Children

Buckingham SC, Marshall GS, Shutze GE, et al; Tick-borne Infections in Children Study Group
J Pediatr. 2007;150:180-184, 184.e1

The goal of the authors was to provide a contemporary descriptive review of cases of Rocky Mountain spotted fever (RMSF) in children, given that there is a relative dearth of information about how the disease presents in children (relative to the published literature on adults with RMSF).

The cases were identified from 6 medical centers in the southeastern and southcentral United States during the period 1990-2002. The authors began the search for cases by looking for rickettsial disease diagnoses among ICD-9 discharge codes at the 6 medical centers. They also searched laboratory data at the centers, along with other sources, in an effort to identify all cases of RMSF. The authors then performed chart review of all cases to collect data on presentation, treatment required, etc.

There were 92 patients with RMSF identified at the 6 centers during the study period; 47% were male. Of the 92 subjects, approximately one third were confirmed cases and two thirds were suspected cases. The median age was 5.8 years, and only 49% reported a tick bite. Only one third reported having been in a wooded area. The median duration of symptoms before admission to hospital was 6 days, but 86% of the patients had made at least 1 healthcare visit before the admission. Four of the patients had received a prescription for doxycycline prior to admission.

The 2 most prevalent symptoms were rash (97%) and fever (98%), but the rash involved the palms and soles in only 65% of subjects. Other than fever and rash, only nausea/vomiting (73%) and headache (61%) were present in more than 50% of cases. The authors calculated that only 58% of subjects had "classic" symptoms of fever, rash, and headache. Fever, rash, and tick exposure were present in only 45% of cases. Median leukocyte counts were not elevated (median, 9500/microliter), but 59% of patients had platelet counts < 150,000/mm³. Liver function studies and clotting labs were normal in the majority of patients.

The median CSF leukocyte count was elevated at 25/mm³, but median values for glucose and protein in the CSF were normal. One third of the patients required ICU care, with 16% having been intubated. Three of the subjects died. Another 15% (n = 13) of subjects had some degree of neurologic deficit at discharge. Ninety percent of the cases occurred between April and September.

The authors concluded that fever and rash are usually present in children with RMSF and that most children are seen by clinicians prior to hospital admission.

One of the best ways to apply the findings of this study to daily practice is to consider the diagnosis of RMSF in any patient with fever plus rash. No other combination of symptoms or findings occurred more commonly, although 58% had the classic findings of fever and rash plus headache. Neither combination would have a very high positive predictive value for RMSF given how common fever and headache are in many pediatric febrile illnesses. However, RMSF is a diagnosis not to miss, so it is important to consider the diagnosis rather than to neglect it. Of course, physicians in more endemic areas should be even more vigilant. there is a useful map of incidence rates across the US by state at the CDC website (http://www.cdc.gov/ncidod/dvrd/rmsf/Epidemiology.htm). The CDC Web page for RMSF has many other resources, including a standard case report form (CDC's RMSF page: http://www.cdc.gov/ncidod/dvrd/rmsf/index.htm).

Abstract