The IHU Mediterranean infection is national reference centre for Q fever. Coxiella burnetii is the bacteria responsible of this infection. The bacterium Coxiella burnetii infection is associated with secretion by the body both many antibodies against the bacteria but also against certain cells of the body (autoantibodies). These autoantibodies may have no effect or be associated with specific symptoms. Anti-Phospholipid antibodies are especially prevalent in the Q fever. Apart from this infection, they are associated with thrombocytopenia, obstetric complications, thrombosis and heart valve damage. These conditions have also been described as complications during Q fever. In a retrospective preliminary work on Q fever, we have shown that the presence of high levels of IgG anti-cardiolipin was associated with the presence of valvular and the evolution to endocarditis. Such associations have a therapeutic involvement and must therefore be confirmed. Indeed, if these associations were confirmed, a trans-esophageal ultrasound could be systematically proposed to patients with valvular disease of trans-thoracique ultrasound but IgG anticardiolipin high levels. Other special attention could be given to patients with high autoantibodies.