Rocky Mountain Spotted Fever: A Note on Some Aspects of Its Epidemiology

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Abstract
Age and sex fatality rates over a 10-yr. period for 2 western states (Montana and Idaho) and 2 eastern states (Maryland and Virginia) have been compared. Crude fatality rates of 18.4% in the eastern states and 28.1% in the western states show no significant differences when broken down by age groups. Under 15 yrs., the rate was 12.9% in the East, 12% in the West; for 15-39 yrs. group 11.1% in the East, 15.1% in the West; and for the group aged over 40, it was 37.6% in the East and 41.8% in the West. Case distribution by ages shows that 502% of all western cases were over 40 yrs. of age; in the East, 46.8% were in the 15 yrs. or younger group. This difference may possibly be due to-occupational contact with the vector and the habitat of Dermacentor variabilis in the East and D. andersoni in the West.