Following a request from the European Commission, a scientific opinion was prepared by EFSA's Animal Health and Welfare Panel to determine the magnitude, distribution, impact and significance of infection and disease in domestic ruminants and humans, risk factors for the maintenance (in domestic ruminant populations) and spillover (from these populations to humans) of Coxiella burnetii (the causative agent of Q fever), and control options in domestic ruminant populations. A range of approaches were used, including an assessment of monitoring/surveillance data, the development of a simple conceptual model, a critical review of available literature, and several country case studies. Control options for C. burnetii infection in small ruminants were qualitatively assessed. Infection is endemic in domestic ruminants in most, if not all, EU member states, however, disease is rare and impact is limited. In the EU, Q fever is a zoonotic disease with limited public health impact, except under certain epidemiological circumstances and for particular risk groups. Human cases are often associated with proximity to small ruminants (particularly at parturition or during abortions) and dry, windy weather. Currently, there is no clear evidence of an association between bacterial genotypes/isolates and virulence. A number of longer-term options to control C. burnetii infection in domestic ruminants were identified; these should be considered in those situations where the public health risk is considered unacceptable. Some additional options were not considered sustainable for long-term control, but may have a role in the face of an outbreak. Persistent environmental contamination may confound animal-based control efforts. Vaccination should be considered a long-term control option, noting that effectiveness may not be observed in the short-term. Antibiotic treatment of animals is not recommended. There is no conclusive evidence that the consumption of milk and milk products containing C. burnetii has resulted in clinical Q fever in humans.