Another example is the relapsing fever by Borrelia. During the first episode, antibodies kill the bacteria and the fever subsides. However, some antigenics variants of the bacteria persist, and after five to seven days these new variants can cause a relapse in the patient with fever reappearing. Other examples of evasion of the immune response are bacteria such as N.gonorrhea, N.meningitidis, Haemphillus influenza, and others that secrete proteases that hydrolyze IgA antibody. Some strains of staphylococci secrete catalase, which prevents them from being killed inside phagocytic cells.