Persistent high antibody titres against Coxiella burnetiiafter acute Q fever not explained by continued exposure to the source of infection: a case-control study

Abstract

BackgroundFrom 2007 to 2010, (the southern part of) the Netherlands experienced a large Q fever epidemic, with more than 4,000 reported symptomatic cases. Approximately 1 - 5% of the acute Q fever patients develop chronic Q fever. A high IgG antibody titre against phase I of Coxiella burnetii during follow-up is considered a marker of chronic Q fever. However, there is uncertainty about the significance and cause of persistence of high IgG phase I antibody titres in patients that do not have any additional manifestations of chronic Q fever. We studied whether continued or repeated exposure to the source of infection could explain elevated IgG phase I antibody levels.MethodsA case-control study was performed to analyze predictors for possible chronic Q fever. Possible chronic Q fever cases (n = 53) are patients with phase I IgG antibody titre ≥1:1,024 at any point in the 9 - 18 months after acute Q fever diagnosis, with a negative PCR test result for C. burnetii DNA and without other disease manifestations. Controls (n = 110) are acute Q fever patients that did not develop chronic Q fever, and who consistently had phase I IgG antibody titre <1:1,024 during the 9 - 18 months follow-up. Binary logistic regression was performed to analyze the effect of living close to an infected farm on the high antibody titres. A longitudinal analysis described the serological profiles of cases and controls.ResultsProximity to infected farms and contact with animal placental material were not associated with an increased risk for possible chronic Q fever. Possible chronic Q fever patients have high IgG phase II as well as IgG phase I antibody titres, even after 48 months of follow-up.ConclusionWe were unable to explain the cause of persistent high IgG phase I titres among possible chronic Q fever patients by being continuously exposed to the source of infection.Electronic supplementary materialThe online version of this article (doi:10.1186/s12879-014-0629-6) contains supplementary material, which is available to authorized users.

Sero-epidemiological survey of Coxiella burnetii in livestock and humans in Tana River and Garissa counties in Kenya

“…This study also collected data through a cross-sectional study design. Thus, we could not accurately determine current infections of C. burnetii in the targeted hosts since antibodies elicited against this pathogen persist for long after infection [66,67]. Therefore, we recommend future studies that have repeated sampling of individuals to obtain samples at both the acute and convalescent phases of disease progression.…”

Reactivation of Q fever: case report of osteoarticular infection developing at the site of a soft tissue injury

“…Between one and five per cent of patients with C. burnetii develop symptomatic persistent focalized infection [ 3 ], more commonly endocarditis than bone infection. Some patients exhibit persistent elevations in phase I antibody titres, without clinical manifestations or ongoing exogenous exposure to the antigen [ 4 ]. Clinical reactivation of Q fever is rare, with limited reports in the setting of parturition, cardiac and orthopaedic surgery.…”

The prognostic value of serological titres in chronic Q fever: treat the patient, not the laboratory data

“…There was no association between serology changes and adverse events. However this relatively short-duration analysis might not have captured some data because of the slow kinetics of C. burnetii antibody changes [10,11]. Serology testing was performed in many different laboratories, using two different immunofluorescence assays (IFA) kits.…”