Routine screening for Coxiella burnetii infection during pregnancy: a clustered randomised controlled trial during an outbreak, the Netherlands, 2010.

Between 2007 and 2010, the Netherlands experienced one of the largest outbreaks of Q fever. Since asymptomatic Coxiella burnetii infection has been associated with maternal and obstetric complications, evidence about the effectiveness of routine screening during pregnancy in outbreak areas is needed. We performed a clustered randomised controlled trial during the Dutch outbreak, in which 55 midwife centres were randomised to recruit pregnant women for an intervention or control strategy. In both groups a serum sample was taken between 20 and 32 weeks of gestation. In the intervention group (n=536), the samples were analysed immediately by indirect immunofluorescence assay for the presence of IgM and IgG (phase I/II) and treatment was given during pregnancy in case of an acute or chronic infection. In the control group (n=693), sera were frozen for analysis after delivery. In both groups 15% were seropositive. In the intervention group 2.2% of the women were seropositive and had an obstetric complication, compared with 1.4% in the control group (Odds ratio: 1.54 (95% confidence interval 0.60-3.96)). During a large Q fever outbreak, routine C. burnetii screening starting at 20 weeks of gestation was not associated with a relevant reduction in obstetric complications and should therefore not be recommended.

Screening for Coxiella burnetii infection during pregnancy: pros and cons according to the Wilson and Jungner criteria.

In Europe the incidence of human Q fever has dramatically increased over the previous years. Untreated infections with Coxiella burnetii, the causal agent of Q fever, have been associated with both obstetric and maternal complications. The majority of pregnant women with a C. burnetii infection remain asymptomatic, hence screening could be of value to prevent unwanted outcomes in this high-risk group. We applied the updated Wilson and Jungner criteria to review the evidence for routine screening for C. burnetii infection during pregnancy. Since much uncertainty remains about the incidence, clinical consequences, diagnostics and treatment of C. burnetii infection during pregnancy, routine screening for C. burnetii infection during pregnancy should not be recommended. Rigorous studies to assess the effectiveness of C. burnetii screening are warranted.

Placental histopathology after Coxiella burnetii infection during pregnancy.

Symptomatic and asymptomatic Coxiella burnetii infection during pregnancy have been associated with obstetric complications. We described placental histopathology and clinical outcome of five cases with asymptomatic C. burnetii infection during pregnancy and compared these cases with four symptomatic cases from the literature. In contrast with the symptomatic cases, we did not observe necrosis or active inflammation in the placentas of the asymptomatic women. Obstetrical outcome was more favourable in the asymptomatic cases than in the symptomatic cases. Asymptomatic and symptomatic C. burnetii infection during pregnancy are different entities with respect to placental histopathology and the risk of obstetric complications.

Effectiveness of the Q fever vaccine: a meta-analysis.

In the Netherlands, the number of notified human Q fever cases showed a steep increase over the last three years and is not expected to disappear in the next few years. Since vaccination might be an option to prevent Q fever cases in the general population, evidence is needed about its effectiveness. We therefore conducted a meta-analysis to determine the evidence base for effectiveness for Q fever vaccination in human populations. We calculated Mantel-Haenszel risk ratios and we used the following formula to calculate the vaccines effectiveness: (1-mhRR) × 100%. Although individual and the pooled estimates showed a high effectiveness of Q fever vaccine, conclusions for the general population cannot be confidently drawn about vaccine effectiveness due to potential flaws in the design of the studies and the selected group of study participants.