[Epidemiology of Lyme borreliosis and neuroborreliosis in France].

Lyme borreliosis (LB) is a systemic disease called neuroborreliosis (NB) when neurological symptoms are pre-eminent. LB is a zoonosis caused by Borrelia bacteria transmitted by Ixodes tick-bite. Because of the absence of a national registry, epidemiology of LB in France is not well known. Moreover, diagnosis of NB may be difficult because of the various clinical forms. Acute meningoradiculitis is the most common presentation, but pauci-symptomatic meningitis, encephalitis, myelitis, polyneuropathy, cerebrovascular involvement, and rarely chronic encephalomyelitis are also described. The vector Ixodes ricinus (I. ricinus) is found throughout metropolitan France excepting border areas of the Mediterranean seaside and in regions with an altitude above 1500 meters. In France, the Borrelia infestation rate of Ixodes is 7% with wide disparity between administrative districts. Prospective work in 1999-2000 by 875 general practitioners participating in the "Sentinel" network established the estimated incidence of BL (9.4/100 000) and of NB (0.6/100 000) in France. Incidence is higher in certain regions: in Alsace, prospective work by 419 general practitioners and specialists in cooperation with the national surveillance agency (Institut national de veille sanitaire), estimated BL incidence at 86 to 200/100 000 inhabitants and NB at 10/100 000. Thus, although globally France is a country with a moderate risk for LB, some regions such as Limousin, Auvergne, Lorraine and Alsace, have a high risk of LB, comparable to countries in the northeastern Europe such as Germany and Sweden.