Is Rocky Mountain Spotted Fever Found Mainly in Mountain Environments?

RMSF was first reported in the U.S. in 1896 in people living in the Rocky Mountains of Idaho and was eventually named after that region. Some investigators suggest the name is misleading because the disease currently is found in most of the U.S. states, with North Carolina and Oklahoma accounting for a total of about 35% of all U.S. cases. States containing the Rocky Mountains (for example, Idaho, Utah) have infection rates of about 0%-3% of cases. Additionally, almost every area in the world (except Antarctica) has reported the disease syndrome similar to RMSF and has isolated Rickettsia spp very similar to R. rickettsii. In the U.S., the fatality rate is about 2%; before effective treatments were available, reported fatality rates varied from 30%-70%.

The age groups at highest risk for infection with RMSF are children under 10 years of age, although any age group can be infected. RMSF has been a reportable disease since the 1920s, and about 250-1,200 cases are reported each year. From about 1972 to about 1990, the average number of cases per year was high (about 1,000) and then decreased until 2001, when the case numbers again climbed and have remained at about 1,000 per year. Recent data suggest the numbers of cases are increasing.