Care for patients with vascular chronic Q fever

Abstract

Q fever is caused by Coxiella burnetii, a Gram-negative and intracellular bacterium. From 2007 to 2010, the Netherlands was confronted with the world’s largest Q fever outbreak. Dairy goats were identified to be the source. At the end of 2009, the outbreak expanded enormously (with 1000 patients in 2008 and 2354 patients in 2009). After months to years, the chronic form of an Q fever infection (chronic Q fever) may develop. Patients with an aneurysm or vascular reconstruction have an increased risk for developing chronic Q fever (vascular chronic Q fever). The clinical presentation is diverse and can be life threatening. Diagnosing chronic Q fever is challenging, because C. burnetii is difficult to culture and the diagnostic performance of single tests are disappointing. The mortality rate of this disease is high and an evidence-based therapeutic guideline is lacking.

A large, multicenter observational study including patients with vascular chronic Q fever was performed in Province of North-East Brabant in the south of the Netherlands. More than a 1000 patients with an aneurysm or central vascular reconstruction were screened for C. burnetii antibodies. Sixty-eight patients with evidence of a chronic Q fever infection were included in a large follow-up study.

The number of infected people with Coxiella burnetii is much higher than expected after the world’s largest Q fever outbreak, with a seroprevalence of Coxiella burnetii antibodies of 16.8% and a high prevalence of chronic Q fever (30.8%) among these patients . Vascular chronic Q fever seems to be the main clinical manifestation of chronic Q fever (30.8% vs. 7.8% for patients with Q fever endocarditis). The variable clinical presentation of vascular chronic Q fever at time of diagnosis is confirmed: 20% of all patients present without any complaints, 50% show non-specific complaints (such as fever, fatigue, weight loss and abdominal pain) and 30% present with an acute aneurysmal related complication, which is significantly higher compared to general population. The mortality rate in patients with vascular chronic Q fever is 23-30%, of which approximately 80% is Q fever related. The use of a diagnostic test such as 18F-FDG-PET is justified within the combination strategy for diagnosing chronic Q fever (combined with the serological profile), as described in the Dutch consensus guideline. Histological examination of a chronic Q fever patients’ vascular wall tissue reveals characteristic features of a necrotising granulomatous infiltration, which is first described within this thesis. The first choice antibiotics (doxycycline/hydroxychloroquine) for patients with vascular chronic Q fever seems not as effective as in patients with Q fever endocarditis. A low rate of cure, 26% of all patients with vascular chronic Q fever, was calculated after 20 months of antibiotic treatment. On top of that, a decline in physical health is observed during follow-up/treatment, which is probably related to the (side) effect(s) of the antibiotic treatment and/or the major surgical intervention. The possible effect of surgery on cure in patients with vascular chronic Q fever patients is a subject for further research.