NATIONAL SURVEILLANCE FOR ROCKY-MOUNTAIN-SPOTTED-FEVER, 1981-1992 - EPIDEMIOLOGIC SUMMARY AND EVALUATION OF RISK-FACTORS FOR FATAL OUTCOME

Between 1981 and 1992, the Centers for Disease Control collected and s ummarized 9,223 cases of Rocky Mountain spotted fever (RMSF) reported from 46 states. Four states (North Carolina, Oklahoma, Tennessee, and South Carolina) accounted for 48% of the reports. The annual incidence per million U.S. population decreased from a high in 1981 of 5.2 to a low in 1992 of 2.0, primarily due to decreased incidence in the south east. Case report forms were filed on 7,650 patients, of whom 4,217 ha d laboratory-confirmed RMSE The age group with the highest incidence w as those 5-9 years of age. Most cases (90.0%) occurred between April 1 and September 30 and included a history of tick attachment (59.6%). R eported symptoms included fever (94.0%), headache (86.2%), myalgia (82 .5%), and rash (80.2%). The case-fatality ratio was 4.0%. Risk factors associated with death included older age, delay in treatment or no tr eatment, and treatment with chloramphenicol (compared with tetracyclin e); however, insufficient data existed to fully assess the confounding effect of severity of illness on antibiotic choice.