Estimating the transfusion transmission risk of Q fever.

BACKGROUND

The Q fever outbreaks in the Netherlands in 2007 to 2009 initiated discussion on the necessity of measures to prevent transmission through blood products. Risk assessments help transfusion regulators decide when and where measures are required. This study assesses the transfusion transmission (TT) risk of Q fever using the European Up-Front Risk Assessment Tool (EUFRAT) model.

STUDY DESIGN AND

METHODS

We estimated the number of Q fever infections in recipients during the 2007 to 2009 outbreaks' peaks using selected notification data; estimates are calculated from the probability of a donor being infected. We compared this probability to the prevalence of infection estimated from an independent donation testing study and using the Biggerstaff model. We also quantified the risk reduction by implementing measures such as donation testing and donor deferral.

RESULTS

At the peak of the 2007, 2008, and 2009 outbreaks, there were an estimated 0.21, 0.96, and 1.59 recipients infected with Q fever, respectively. Between June 1, 2009, and January 31, 2010, the probability of a donor being infected with Q fever in the high-incidence areas was estimated at 260 (95% confidence interval, 192-340) per 100,000 donors, consistent with results from the donation testing study. The EUFRAT estimates were also consistent with estimates from the Biggerstaff model. Scenario analyses showed that donation testing provided the largest risk reduction of various risk reduction strategies.

CONCLUSION

The TT risk of Q fever during the 2007 to 2009 outbreaks was small, a result that is consistent with results of other studies. EUFRAT can be applied successfully to support decision making during outbreaks.