LYME BORRELIOSIS. Lyme borreliosis (LB) is the most common vector-borne disease in the Northern Hemisphere, caused by the bacterium Borrelia burgdorferi sensu lato, transmitted to humans by a bite of ticks Ixodes. Prevention is based on simple measures to evict ticks, and on their rapid extractionin the event of a bite. The diagnosis of LB is based on 3 arguments: an exposure to tick bites; clinically compatible symptoms (cutaneous, neurological or rheumatological manifestations, +/- functional symptoms such as fatigue or polyarthromyalgia), evolving in 3 stages (early localized or erythema migrans, early or late disseminated LB); a positive two-tier serological test (ELISA +/- Western-Blot). Serology can be negative for the first 6 weeks, without excluding the diagnosis. Since serology can remain positive for life, evolution is only evaluated clinically. LB treatment is mainly based on doxycycline for 14 to 28 days, depending on the clinical stage and manifestations, without demonstrated interest in prolonging it, even if symptoms persist. Nonetheless their management is crucial as often responsible for medical wandering. Attentive listening to the patient is essential. The prognosis of LB in the medium-term is favorable, especially if they beneficiate of an early management.

La borréliose de Lyme est la principale zoonose vectorielle en France. Elle est due à la bactérie Borrelia burgdorferi sensu lato, transmise lors d’une piqûre de tique infectée du genre Ixodes. Son diagnostic repose sur un trépied diagnostique, parfois incomplet. La prévention consiste en la protection contre les piqûres de tiques, et leur extraction rapide en cas de piqûre. Le traitement repose principalement sur la doxycycline.