Lyme borreliosis and other tick-borne diseases. Guidelines from the French scientific societies (II). Biological diagnosis, treatment, persistent symptoms after documented or suspected Lyme borreliosis

•The serodiagnosis of Lyme borreliosis relies on a two-stage strategy: firstly, a screening test using an immune-enzymatic technique (ELISA), and secondly, in case of positivity, a confirmatory test using a western-blot technique for its better specificity. For erythema migrans, Lyme serology has poor sensitivity (30–40%) and should not be performed. Serological follow-up is not recommended. For neuroborreliosis, it is recommended to perform ELISA tests in simultaneous samples of blood, and cerebrospinal fluid, to test for intrathecal synthesis of Lyme antibodies.•Given the continuum between early localised, and disseminated borreliosis, and the efficacy of doxycycline for treatment of neuroborreliosis, doxycycline is preferred as first-line regimen for erythema migrans and neuroborreliosis. Treatment of articular manifestations of Lyme borreliosis relies on doxycycline, ceftriaxone or amoxicillin. In patients with persistent symptoms after adequate treatment of Lyme borreliosis, it is recommended not to repeat, or prolong, antibacterial treatment.•Some patients suffer from persistent and pleomorphic symptoms after documented or supposed Lyme borreliosis. Another condition is eventually diagnosed in 80% of them. Among these other conditions, the positive diagnosis of persistent somatic symptoms (PSS) relies on a careful diagnostic workout and will allow to initiate specific therapeutic interventions.