Proceedings of the 2013 annual meeting of the Netherlands Epidemiology Society
Volume 1 Issue S1 Abstract 25
C.C.H. (Lieke) Wielders (1,2), P.C.A. (Alex) Wijnbergen (1), J.J.A. (Jeroen) Schellekens (3), P.M. (Peter) Schneeberger (1), P.C. (Peter) Wever (1), M.H.A. (Mirjam) Hermans (3)
1. Department of Medical Microbiology and Infection Control, Jeroen Bosch Hospital, ’s- Hertogenbosch, the Netherlands
2. Centre for Infectious Disease Control, National Institute for Public Health and the Environment (RIVM), Bilthoven, the Netherlands
3. Molecular Diagnostics, Jeroen Bosch Hospital, ’s-Hertogenbosch, the Netherlands
PCR is very effective in diagnosing acute Q fever at the early stages of infection, when bacterial DNA is present in the bloodstream but antibodies have not yet developed. The objective of this study was to determine the diagnostic value of real- time PCR (qPCR) in diagnosing acute Q fever in an outbreak situation.
At the Jeroen Bosch Hospital, in 2009, qPCR for Coxiella burnetii DNA was performed for 2,715 patients suspected of acute Q fever (positive: n=385; negative: n=2,330). Sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of the qPCR were calculated for patients with a negative qPCR result with a follow-up sample within 14 days (n=305), and qPCR positive patients with at least one follow-up sample (n=369). The correctness of the qPCR was based on immunofluorescence assay results of samples submitted for qPCR and follow-up.
Sensitivity of the Q fever qPCR was 92.2%, specificity 98.9%, PPV 99.2%, and NPV 89.8%. Patients who later developed a serologic profile indicative of chronic Q fever infection had a significantly higher DNA load during the acute phase than patients who did not (p<0.001).
qPCR is a valuable tool in the diagnosis of acute Q fever and should be used in outbreak situations when onset of symptoms is <15 days. Special attention is needed in the follow-up of patients with a high C. burnetti DNA load during the acute phase, as this might be indicative for the development of a serologic profile indicative of chronic Q fever.
Published: 06 Jun, 2013