Q fever in Spain: Epidemiology and demographic characteristics of hospitalized patients (2016–2023)

BACKGROUND: Q fever, caused by Coxiella burnetii, is a zoonosis with significant public health implications. This study described the epidemiology, demographic and clinical characteristics, clinical and hospitalization burdens, and geographical distribution of hospitalized Q fever patients in Spain from 2016 to 2023. METHODS: We conducted a nationwide, retrospective study using a nationwide registry between 2016 and 2023. We analyzed temporal trends, demographic data, comorbidities, complications, and mortality. RESULTS: We identified 3358 hospitalizations for Q fever, representing an overall hospitalization rate of 0.89 per 100,000 population. The median patient age was 56 years, and the cohort was predominantly male (72%). The median hospital length of stay was 9 days (IQR 6-15). The overall mortality rate was 2.4%. The most common complication was pneumonia (32%). The highest hospitalization rates in the Canary Islands, and La Rioja. CONCLUSION: The risk of hospitalization increases with age and the presence of predisposing conditions. The marked regional heterogeneity and high frequency of complications such as pneumonia underscore the need for enhanced surveillance and a strengthened One Health approach to control this zoonosis.