Acute Q fever in Majorca island 2017-2022. An underestimated problem

Q fever (QF) is a zoonotic infection caused by Coxiella burnetii. Previous studies suggest that the incidence in the island of Majorca may be high. The objective was to know the epidemiological, clinical, diagnostic, and therapeutic characteristics of acute QF (AQF) on the island of Majorca during the years 2017-2022.

Retrospective analysis of a series of cases of AQF diagnosed in 3 out 4 hospitals of the Health Service of the island of Majorca. AQF was considered if a clinically compatible syndrome was present with one of the following serological criteria: confirmed AQF if IgG seroconversion phase II, very possible if only IgG ≥1/128 is available in addition to a positive IgM, and AQF possible if IgG≥ 1/512 with negative IgM or if IgM positive with negative IgG in a single serological determination.

223 cases of AQF were diagnosed, of which 102 (45.7%) were confirmed, 84 (37.7%) very probable and 37 (16.6%) probable AQF. Prolonged febrile syndrome was the most frequent clinical diagnosis (107, 48.0%), followed by pneumonia with/without pleural effusion (49, 21.9%), acute hepatitis (38, 17.0%), pericarditis and/or myocarditis (6, 2.6%). Three patients developed endocarditis (one in the acute phase, two others during follow-up). The median number of cases per year was 34 (p25-p75: 31.7-40.25). AQF-related mortality was 1.8% (4 patients).

AQF is a preventable and little recognized zoonosis, causing significant morbidity and mortality in Majorca.