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SUMMARYBetween 1972 and 1988 we have serologically confirmed 103 Coxiella burnetii infections: 46 were acute, 5 were chronic, 52 represented past infections. Details of 61 cases are presented.Of acute cases 80 % had respiratory involvement; at least 63 % had pneumonias. The incidence (22 %) of neurological complications was of particular interest; 40% of these patients had prolonged sequelae. One acutely ill patient died of fulminating hepatitis. Patients with pre-existing pathology or immunosuppression were especially susceptible to C. burnetii.In the absence of acute sera, the complement fixation test alone provided inadequate differentiation between recent and past Q fever: phase II titres persisted at 3 80 for more than 1 year after the acute infection in 15 cases; maximum duration of persistence was 14 years. Three patients acquired high phase I titres.Only 5% of cases had chronic Q fever, but in view of the diverse sequelae observed in this series, we suggest that long-term serological and clinical followup of all cases of Q fever is fully justified.

Aims-To validate the sensitivity of universal antenatal screening for hepatitis B surface antigen (HBsAg) by testing pools of 10 sera, and to review 10 years' experience using this method. Methods-66 945 antenatal patients were tested between 1986 and 1996 using the pooled method. All sera from 1996 (n = 6050) were retrieved and retrospectively tested individually. An in vitro determination of the eVect of pooling on sensitivity was performed by checkerboard neutralisation assay. Results-26 HBsAg positive women were detected by universal screening over 10 years; 12 had non-European surnames and five had known risk factors for hepatitis B infection. High titre anti-HBs sera in the pool reduced the sensitivity of the HBsAg assay, though the eVect was only significant at low levels of HBsAg carriage. Conclusions-The prevalence of hepatitis B is extremely low in the antenatal population served by Plymouth PHL. Pooling is unlikely to reduce sensitivity enough to lead to significant preventable vertical transmission, and is a costeVective and valid strategy in areas of low seroprevalence. (J Clin Pathol 1998;51:392-395)

DevonSUMMARY IgM rheumatoid factor was assayed by three routine methods: latex fixation; haemagglutination; and end point laser nephelometry in 69 patients with definite or classical rheumatoid arthritis and 58 patients with other non-rheumatoid arthropathies, selected prospectively according to the American Rheumatism Association clinical criteria. The operators of the assays were unaware of the clinical diagnoses. In the group with rheumatoid arthritis 75-4% were positive by latex fixation, 73*9% by haemagglutination, and 55 1% by nephelometry. In the group with nonrheumatoid arthropathies 10-4% were positive by latex fixation, 8-6% by haemagglutination, and 10-4% by nephelometry. Thus the simple and inexpensive latex fixation test was as good as the haemagglutination test, and both were significantly better than nephelometry in the laboratory confirmation of the clinical diagnosis of definite or classic rheumatoid arthritis (X2 = 5.40 and 4 56, and p < 0 025 and < 0 05, respectively). None of these tests was significantly better or worse than the others in producing positive results in the group with non-rheumatoid arthropathies.

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