IgM globulin response in Q fever (Coxiella burneti) infections

The IgM globulin response has been measured following the onset of primary Q fever infections. A complement fixation test method was used to measure the IgM after separation by ultracentrifugation in a sucrose density gradient. Specific IgM was demonstrable between 2 and 10 wk after onset of symptoms. The test can be used to confirm a recent infection when only a 'convalescent' blood specimen has been collected and will be useful in the assessment of workers' compensation claims.