Acute Q fever in patients with an influenza-like illness in regional New South Wales, Australia.

• Published in: PLOS Neglected Tropical Diseases
• Main Authors: Chaturaka Rodrigo, Gregory Walker, Andrea T K Sevendal, Chelsea Nguyen, Sacha Stelzer-Braid, William Rawlinson, Stephen Graves, Heather F Gidding, John Stenos, Andrew R Lloyd
• Format: Article in Journal/Newspaper
• Language: English
• Published: Public Library of Science (PLoS) 2024
• Subjects: Arctic medicine. Tropical medicine; RC955-962; Public aspects of medicine; RA1-1270; Arctic
• Online Access: https://doi.org/10.1371/journal.pntd.0012385; https://doaj.org/article/36659ac14d304a9c8eeb01b5c6008d3e

Introduction Query (Q) fever is a zoonosis caused by the bacterium Coxiella burnetii typically presenting as an influenza-like illness (ILI) with or without hepatitis. The infection may be missed by clinicians in settings of low endemicity, as the presentation is clinically not specific, and there are many more common differential diagnoses for ILI including SARS-CoV-2 infection. Methods Residual serum samples were retrospectively tested for Phase 1 and 2 Q fever-specific IgM, IgG, IgA antibodies by indirect immunofluorescence and C. burnetii DNA by polymerase chain reaction. They had not been previously tested for Q fever, originating from undiagnosed patients with probable ILI, aged 10-70 years and living in regional New South Wales, Australia. The results were compared with contemperaneous data on acute Q fever diagnostic tests which had been performed based on clinicians requests from a geographically similar population. Results Only one (0.2%) instance of missed acute Q fever was identified after testing samples from 542 eligible patients who had probable ILI between 2016-2023. Laboratory data showed that during the same period, 731 samples were tested for acute Q fever for clinician-initiated requests and of those 70 (9.6%) were positive. Probability of being diagnosed with Q fever after a clinician initiated request was similar regardless of the patients sex, age and the calendar year of sampling. Conclusion In this sample, Q fever was most likely to be diagnosed via clinician requested testing rather than by testing of undiagnosed patients with an influenza like illness.