Chronic Q fever in abdominal aortic disease

After the Q fever outbreak in The Netherlands, approximately >40.000 people
were infected with Coxiella burnetii, the bacterium that causes Q fever. Of
these, more than 500 patients developed chronic Q fever. Chronic Q fever is a
life-threatening disease which infects the vascular walls, vascular prosthesis
and heart valves. Risk factors for developing chronic Q fever are a history of
aneurysm or vascular prosthesis. After the outbreak, patients with an aneurysm
or vascular prosthesis of the abdominal aorta were serologically screened for
C. burnetii. Now, ten years after the start of the Q fever outbreak, we would
like to complete follow-up of these patients. It is known that chronic Q fever
can develop for years after the initial infection. Every year, new patients are
diagnosed with chronic Q fever. Chronic Q fever knows a diagnostic delay,
resulting in patients being diagnosed with already serious complications.
Therefore, mortality rates among chronic Q fever patients are high.

The objective of this study is to determine the incidence of chronic Q fever
and seronegativity in vascular patients that were seropositive after the Dutch
Q fever outbreak. Seropositivity can indicate a past resolved Q fever infection
or chronic Q fever infection. These prevalences can also be used in the
decision for a national screening programme.

Follow-up will be done by measuring the phase I and II IgG antigens against
Coxiella burnetii in serum. Vascular patients that were already seropositive
have an indication for follow-up of their serology, but vascular patients that
became seronegative will be screened in the context of this study. Patients
will be recruited by the treating vascular surgeon. First, they will receive an
invitation letter via the post or during an appointment at the outpatient
clinic. After receiving this letter, Bianca Buijs or a representative will
contact the patient by telephone to ask if they would like to participate in
the study. Informed consent will then be obtained and an appointment for
venepuncture will be made. Patients who declined informed consent the first
time will not be approached again.

One venepuncture will be perfomed for measurement of phase I and II IgG
antigens against Coxiella burnetii. If serology indicates a possible chronic Q
fever infection, we will refer patients to a infectious disease specialist for
additional testing and, if necessary, treatment.