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The prevalence of Coxiella burnetti infection (Q fever) was determined among Nova Scotia (N.S.) and Prince Edward Island (P.E.I.) blood donors by using the complement fixation and microimmunofluorescence (IF) test. The complement fixation and IF antibody tests measured antibody prevalence for the phase II or phase I and II antigens, respectively. Complement-fixing antibodies to phase II antigen were detected in 4.1% of 997 N.S. and 5.0% of 219 P.E.I. blood donors. Anti-phase II antibodies were detected by microimmunofluorescence in 11.8 and 14.6% of the blood donors in the two provinces, respectively. Anti-phase I antibodies were detected among 2.8% of the N.S. blood donors and 6.3% of the P.E.I. blood donors. Comparison of rates of anti-phase II IF by counties in N.S. revealed that there was at least one county where infection by C. burnetti is hyperendemic. Rates of antibody prevalence were similar in all three areas of P.E.I. examined. We conclude that "Q fever" is endemic in N.S. and P.E.I. and that the microimmunofluorescence test is more suitable than the complement fixation test for seroepidemiologic studies.

Species-specific antigens from Rickettsia typhi and Rickettsia prowazekii were readily solubilized by French pressure cell extraction or sonication of Renografin density gradient-purified rickettsiae and were identified by rocket immunoelectrophoresis. As measured by quantitative rocket immunoelectrophoresis, the species-specific typhus rocket antigens (STRAs) appeared to be proteins; they were denatured by heating at 560C for 30 min but not by 50°C treatment, and they were sensitive to pronase and trypsin but were not affected by periodate oxidation, glycosidases of various specificities, phospholipase A, or lipase. STRAs from both R. typhi and R. prowazekii were separated from common antigens by DE52 column chromatography of 100,000-x-g supernatant fractions of rickettsial extracts. The purified STRAs were characterized by crossed immunoelectrophoresis, by polyacrylamide gel electrophoresis on Davis and sodium dodecyl sulfate gels, and by an enzyme-linked immunosorbent assay. The two purified STRAs were proteins with similar native electrophoretic mobilities in agarose and polyacrylamide gels, and these proteins had similar polypeptide pattems on sodium dodecyl sulfate gels. Most of the STRA activity migrated as a single protein band on sodium dodecyl sulfate-polyacrylamide and Davis polyacrylamide gels, although minor protein bands with STRA activity were also detected. The major STRA proteins constituted 10 to 15% of the total cellular protein of R. typhi and R. prowazekii. According to sensitive enzyme-linked immunosorbent assay titrations, the STRA of R. prowazekii had substantial cross-reactivity with rabbit antiserum prepared against R. typhi, as shown also by rocket immunoelectrophoresis, whereas the STRA of R. typhi reacted only very weakly with antiserum prepared against R. prowazekii according to the enzyme-linked immunosorbent assay and not at all according to rocket immunoelectrophoresis.

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