Coxiella burnetii causes Q-fever (QF), which may result in Q-fever-fatigue-syndrome (QFS), severely impacting patients’ quality of life. This study aimed to investigate the occurrence of Q-fever-fatigue-syndrome (QFS) after QF infection from a large outbreak (77 detected cases) in July 2019 in rural Southwest Germany.
Patients with positive phase II IgM and IgG antibodies against Coxiella burnetii were included. To determine a QFS, a questionnaire was created and validated, with questions on onset and duration of fatigue, with frequently mentioned symptoms of QFS, possible risk factors and a validated questionnaire to determine the severity of fatigue (CIS20R – Checklist individual strength). The filled out questionnaire and antibody-titers were examined at five sampling times within two years. Due to the COVID-19 pandemic and its possible influence on fatigue-symptoms, data from the second year were excluded from the analysis. Composition of study population, responses of participants and antibody-titers were analyzed descriptively by using SAS-software.
31 participants were recruited for the study; 48% were female, 25% hospitalised and 51% had pneumonia. Median age was 53 years [IQR: 24-88 years]. QFS was identified in 6 participants (20%, 50% female). There was no significant correlation between development of QFS and age or previous illnesses (Fisher's Exact Test). Likewise, data showed no correlation between QFS and the severity (pneumonia, hospitalization) nor between QFS and high levels of antibody-titers (IgG>1:4096).
The analysis did not provide insight into the OR/RR of developing QFS, due to the relative small study population. However, 20% of study cases developed QFS, which confirms findings by other international studies. Furthermore, the created questionnaire will be included in national guidelines for QF, helping doctors diagnose QFS as an officially recognized illness. Further long-term studies are necessary, preferably with international partners to extend the cohort, in order to identify possible risk factors and to establish a harmonized procedure for diagnosing QFS throughout Europe.