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Q-fever in the Netherlands
Since 2007 the Netherlands
has been faced with a severe outbreak of Q-fever. Over the past 3 years almost
3500 people have been diagnosed with the disease, some suffering from chronic
infections or chronic fatigue syndrome. In the Netherlands Q-fever-infected
large dairy goat farms, and to a lesser extent dairy sheep farms, are related
to the human epidemic.
Detection of Coxiella burnetii using (q)PCR: a comparison of
available assays
Q fever, caused by the bacterium Coxiella burnetii, has become an emerging
public health problem in the Netherlands since 2007. Diagnosis of Q fever,
both in humans and animals, is mainly based on serology. Serological techniques
are less suitable for direct transmission and source-finding studies for C.
burnetii infection due to the delayed detection window for serological tests.
The last two decades, several PCR based diagnostic assays (conventional PCR
or qPCR) have been developed for the detection of C. burnetii DNA. These assays
have been applied for the detection of C. burnetii DNA in clinical samples,
veterinary samples, and environmental samples. These PCR-based diagnostic
tests are often "in-house" developed assays. A number of commercial
PCR diagnostic tests, however, have also become available. A drawback of these
commercial kits is that information on some of the components is patented.
This makes a thorough assessment of assay performance in relation to other
"inhouse" developed assays difficult. In the current study, we describe
a comparison of various (q)PCR assays used by laboratories both nationally
and internationally for the detection of C. burnetii DNA. We compare the results
obtained from three ring trials, set up specifically for the detection of
C. burnetii DNA in human, veterinary, or environmental matrices. In addition,
we compare specific parameters, such as sensitivity, specificity, and reproducibility
for each of the (q)PCR assays. In conclusion, most (q)PCR assays developed
for C. burnetii include detection of the multicopy insertion element IS1111,
in combination with detection of other single copy genes such as icd, com1,
sod, or plasmid genes. PCR based detection assays (conventional PCR or qPCR)
for C. burnetii DNA preferably target short and multiple target sequences,
including an internal process control in multiplex format. Other performance
characteristics have not yet been published for these qPCR assays for the
detection of C. burnetii, although this would be recommended.
Full report.
Tough
lessons from Dutch Q-fever outbreak
Factsheet
Q-fever Netherlands
RIVM
and CVI reports on Q-fever