Q fever among blood donors
Project leader: Prof Hans Zaaijer MD PhD
In 2007, 2008 and 2009 outbreaks of Q fever occurred in the Netherlands with increasing magnitude, caused by the release of large amounts of Coxiella burnetii spores in the environment. The 2009 outbreak with 2,354 reported cases is the largest human Q fever outbreak ever recorded.
To assess the extent of infection and the safety of donated blood, we tested local blood donations for presence of C. burnetii-antibodies and -DNA. Starting May 2009, over 40,000 serum samples were collected from all consenting blood donors in the areas with high Q fever incidence. A PCR for detection of C. burnetii DNA was developed. The 1,004 samples from the areas with the highest number of reported cases were tested for presence of C. burnetii DNA. Seroprevalence and incidence were determined using ELISA and immunofluorescence assays (IFAs) in the subset of 543 donors, of whom a follow-up sample was available. 6/1,004 donor samples tested reactive for C. burnetii DNA.
Confirmatory testing (IFA) on the index and follow-up samples demonstrated seroconversion in 2 donors; high-level pre-existing antibodies in 1 donor and no seroconversion in 3 donors. Thus, 3/1,004 blood donations were proven to contain C. burnetii DNA. IgG testing of the 543 serum pairs showed that 66 (12.2%) were reactive in the latest sample, of which 10 represented seroconversions. The ten seroconversions result in an incidence of 5.7% per year, which is more than 10-fold higher than the local number of reported clinical cases (0.47% per year).