Elizabeth A. Casper

499 EPIDEMIOLOGICAL ASPECTS OF ROCKY MT SPOTTED FEVER (RMSF) IN N.C. 1979–80

A prospective, case controlled, epidemiologic study of RMSF was begun in Rowan and Cabarrus Counties in July, 1979. A confirmed case has a 4 × fold rise in specific R. rickettsii antibodies. [indirect hemagglutination (IHA), microimmunofluorescence (MIF) or latex agglutination (LA)] or presence of IgM-MIF R. rickettsii antibodies. Disconfirmed cases have no detectable antibodies or stationary titers. Disconfirmed cases and case controls selected by age and neighborhood proximity have been compared to confirmed cases of RMSF. 78 suspect cases were identified in 1979 and 151 in 1980. 22 cases were confirmed in 1979 and 21 in 1980. These data produce an estimated rate of 12.4 confirmed symptomatic cases/100,000/year in Rowan and Cabarrus Counties, N.C. The 3 groups of patients did not differ in the month of onset of illness or sex. The majority of serologically confirmed cases occurred in males. Females were less likely to contract disease over 10 years of age. There is a striking preponderance of white patients. The possibility of hyperendemic foci for disease is suggested by geographical clustering of confirmed cases. There was a greater likelihood of a history of tick exposure or bite in proven cases, but it was not satistically different from the other 2 groups. Children are brought sooner for medical care with an illness than adults seeking assistance for themselves. Delay in initiation of therapy results from failure to make the diagnosis rather than from failure to seek medical care. There is no correlation of educational differences in patients or parents with delay in seeking physician assistance.