Clinical and laboratory features, hospital course, and outcome of Rocky Mountain spotted fever in children.

OBJECTIVES: To describe the clinical characteristics and course of children with laboratory-diagnosed Rocky Mountain spotted fever (RMSF) and to identify clinical findings independently associated with adverse outcomes of death or discharge with neurologic deficits. STUDY DESIGN: Retrospective chart review of 92 patients at six institutions in the southeastern and southcentral United States from 1990 to 2002. Statistical analyses used descriptive statistics and multiple logistic regression. RESULTS: Children with RMSF presented to study institutions after a median of 6 days of symptoms, which most commonly included fever (98%), rash (97%), nausea and/or vomiting (73%), and headache (61%); no other symptom or sign was present in >50% of children. Only 49% reported antecedent tick bites. Platelet counts were <150,000/mm3 in 59% of children, and serum sodium concentrations were <135 mEq/dL in 52%. Although 86% sought medical care before admission, only 4 patients received anti-rickettsial therapy during this time. Three patients died, and 13 survivors had neurologic deficits at discharge. Coma and need for inotropic support and intravenous fluid boluses were independently associated with adverse outcomes. CONCLUSIONS: Children with RMSF generally present with fever and rash. Delays in diagnosis and initiation of appropriate therapy are unacceptably common. Prognosis is guarded in those with hemodynamic instability or neurologic compromise at initiation of therapy.

La Crosse encephalitis in Eastern Tennessee: clinical, environmental, and entomological characteristics from a blinded cohort study.

A blinded cohort study was conducted in 2000 to better understand the emergence of La Crosse virus infection in eastern Tennessee, with special emphasis on the potential mosquito vector(s). Children with suspected central nervous system infection were enrolled at the time of clinical presentation at a large pediatric referral hospital. Clinical, environmental, and entomological data were collected prior to case confirmation. Sixteen of the 40 children included in the final analysis were confirmed to have La Crosse infection by a fourfold increase in antibody titers between collection of acute- and convalescent-phase sera. Factors significantly associated with La Crosse infection included average number of hours per day spent outdoors (5.9 for La Crosse virus cases vs. 4.0 for noncases, p = 0.049); living in a residence with one or more tree holes within 100 m (relative risk = 3.96 vs. no tree holes within 100 m, p = 0.028); and total burden of Aedes albopictus (number of female and male larvae and adults collected at a site), which was more than three times greater around the residences of La Crosse virus cases versus noncases (p = 0.013). Evidence is accumulating that the newly introduced mosquito species Ae. albopictus may be involved in the emergence of La Crosse virus infection in eastern Tennessee.