Epidemiology and Infection

Original Papers

Q fever

In search of hidden Q-fever outbreaks: linking syndromic hospital clusters to infected goat farms

C. C. VAN DEN WIJNGAARDa1 c1, F. DIJKSTRAa1, W. VAN PELTa1, L. VAN ASTENa1, M. KRETZSCHMARa1a2, B. SCHIMMERa1, N. J. D. NAGELKERKEa3, P. VELLEMAa4, G. A. DONKERa5 and M. P. G. KOOPMANSa1a6

a1 National Institute for Public Health and the Environment, Bilthoven, The Netherlands

a2 Julius Centre for Health Sciences and Primary Care, University Medical Centre Utrecht, The Netherlands

a3 United Arab Emirates University, Al-Ain, United Arab Emirates

a4 Animal Health Service, Deventer, The Netherlands

a5 Nivel, Netherlands Institute of Health Services Research, Utrecht, The Netherlands

a6 Erasmus Medical Center, Rotterdam, The Netherlands

SUMMARY

Large Q-fever outbreaks were reported in The Netherlands from May 2007 to 2009, with dairy-goat farms as the putative source. Since Q-fever outbreaks at such farms were first reported in 2005, we explored whether there was evidence of human outbreaks before May 2007. Space–time scan statistics were used to look for clusters of lower-respiratory infections (LRIs), hepatitis, and/or endocarditis in hospitalizations, 2005–2007. We assessed whether these were plausibly caused by Q fever, using patients' age, discharge diagnoses, indications for other causes, and overlap with reported Q fever in goats/humans. For seven detected LRI clusters and one hepatitis cluster, we considered Q fever a plausible cause. One of these clusters reflected the recognized May 2007 outbreak. Real-time syndromic surveillance would have detected four of the other clusters in 2007, one in 2006 and two in 2005, which might have resulted in detection of Q-fever outbreaks up to 2 years earlier.

(Accepted April 14 2010)

(Online publication May 18 2010)

Correspondence:

c1 Author for correspondence: C. C. van den Wijngaard, M.Sc., RIVM, Centre for Infectious Disease Control Netherlands, PO Box 1, 3720 BA Bilthoven, The Netherlands. (Email: kees.van.den.wijngaard@rivm.nl)

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