Characteristics of hospitalized acute Q fever patients during a large epidemic, The Netherlands.

BACKGROUND: From 2007 to 2009, The Netherlands experienced a major Q fever epidemic, with higher hospitalization rates than the 2-5% reported in the literature for acute Q fever pneumonia and hepatitis. We describe epidemiological and clinical features of hospitalized acute Q fever patients and compared patients presenting with Q fever pneumonia with patients admitted for other forms of community-acquired pneumonia (CAP). We also examined whether proximity to infected ruminant farms was a risk factor for hospitalization. METHODS: A retrospective cohort study was conducted for all patients diagnosed and hospitalized with acute Q fever between 2007 and 2009 in one general hospital situated in the high incidence area in the south of The Netherlands. Pneumonia severity scores (PSI and CURB-65) of acute Q fever pneumonia patients (defined as infiltrate on a chest x-ray) were compared with data from CAP patients. Hepatitis was defined as a >twofold the reference value for alanine aminotransferase and for bilirubin. RESULTS: Among the 183 hospitalized acute Q fever patients, 86.0% had pneumonia. Elevated liver enzymes (alanine aminotransferase) were found in 32.3% of patients, although hepatitis was not observed in any of them. The most frequent clinical signs upon presentation were fever, cough and dyspnoea. The median duration of admission was five days. Acute Q fever pneumonia patients were younger, had less co-morbidity, and lower PSI and CURB-65 scores than other CAP patients. Anecdotal information from attending physicians suggests that some patients were admitted because of severe subjective dyspnoea, which was not included in the scoring systems. Proximity to an infected ruminant farm was not associated with hospitalization. CONCLUSION: Hospitalized Dutch acute Q fever patients mostly presented with fever and pneumonia. Patients with acute Q fever pneumonia were hospitalized despite low PSI and CURB-65 scores, presumably because subjective dyspnoea was not included in the scoring systems.

Identification of risk factors for chronic Q fever, the Netherlands.

Since 2007, the Netherlands has experienced a large Q fever outbreak. To identify and quantify risk factors for development of chronic Q fever after Coxiella burnetii infection, we performed a case-control study. Comorbidity, cardiovascular risk factors, medications, and demographic characteristics from 105 patients with proven (n = 44), probable (n = 28), or possible (n = 33) chronic Q fever were compared with 201 patients who had acute Q fever in 2009 but in whom chronic Q fever did not develop (controls). Independent risk factors for development of proven chronic Q fever were valvular surgery, vascular prosthesis, aneurysm, renal insufficiency, and older age.

Microbiological challenges in the diagnosis of chronic Q fever.

Diagnosis of chronic Q fever is difficult. PCR and culture lack sensitivity; hence, diagnosis relies mainly on serologic tests using an immunofluorescence assay (IFA). Optimal phase I IgG cutoff titers are debated but are estimated to be between 1:800 and 1:1,600. In patients with proven, probable, or possible chronic Q fever, we studied phase I IgG antibody titers at the time of positive blood PCR, at diagnosis, and at peak levels during chronic Q fever. We evaluated 200 patients, of whom 93 (46.5%) had proven, 51 (25.5%) had probable, and 56 (28.0%) had possible chronic Q fever. Sixty-five percent of proven cases had positive Coxiella burnetii PCR results for blood, which was associated with high phase I IgG. Median phase I IgG titers at diagnosis and peak titers in patients with proven chronic Q fever were significantly higher than those for patients with probable and possible chronic Q fever. The positive predictive values for proven chronic Q fever, compared to possible chronic Q fever, at titers 1:1,024, 1:2,048, 1:4,096, and ≥1:8,192 were 62.2%, 66.7%, 76.5%, and ≥86.2%, respectively. However, sensitivity dropped to <60% when cutoff titers of ≥1:8,192 were used. Although our study demonstrated a strong association between high phase I IgG titers and proven chronic Q fever, increasing the current diagnostic phase I IgG cutoff to >1:1,024 is not recommended due to increased false-negative findings (sensitivity < 60%) and the high morbidity and mortality of untreated chronic Q fever. Our study emphasizes that serologic results are not diagnostic on their own but should always be interpreted in combination with clinical parameters.

[Screening for chronic Q fever in symptomatic patients with an aortic aneurysm or prosthesis]. / Screening op chronische Q-koorts bij symptomatische patiënt met aneurysma of prothese van de aorta.

A 76-year-old man was referred to the Emergency Department because of collapse, epigastric pain and nausea. The patient had been diagnosed with an infrarenal aneurysm of the abdominal aorta nine years earlier. His symptoms were attributed to an aortic-duodenal fistula originating from the aneurysm. The patient died despite placement of an aortic prosthesis. A hospital screening programme for chronic Q fever in patients with aortic aneurysm revealed chronic Q fever. Until recently, vascular infection with Coxiella burnetii was an unknown disease in the Netherlands. In view of the nonspecific clinical presentation, severity and therapeutic consequences of the disease, we advise screening for chronic Q fever in all symptomatic patients with an aortic aneurysm or prosthesis - whether or not with aspecific symptoms - in regions where the disease is endemic.