Patients with an aneurysm or vascular graft will be screened for chronic Q-fever. Patients with chronic Q-fever will be included in a follow-up program, in which additional research and treatment will start. The initial treatment of patients with chronic Q-fever is doxycycline and hydroxychloroquine for at least 18 months. In addition, patients will be monitored in 3-monthly controls, blood samples and imaging will be done. Parameters as complaints, titers, circulating DNA, grow of aneurysm, complications etc. will be investigated.