La borreliosi di Lyme e la sua diffusione in Italia

Lyme borreliosis (LB) is a tick borne spirochetosis first reported in 1975 in the town of Lyme (Connecticut, USA). In Italy the first case was observed in Liguria in 1983. LB is a multisystemic infection involving skin, joints, nervous system, eyes and heart. The prevalence of LB reflects the geographic areas where the vectors are present. Hard tick Ixodes ricinus is the most common vector, but also other haematophagous arthopodes, such as tabanides and fleas are considered vectors of Borrelia burgdorferi. At present there is no map of the tick distribution in Italy. The infection is endemic in the woody areas of the Alps and their neighbouring Regions Friuli Venezia Giulia, Liguria, Trentino Alto Adige, some areas of Veneto and north-west Tuscany and Emilia Romagna. Some sporadic reports suggest that Borrelia burgdorferi infection is present also in other Italian regions. However, it is currently difficult to present conclusive epidemiologic data on LB. In fact there are no widely accepted case definitions for the numerous clinical features due to or linked to Borrelia burgdorferi infection and the incidence and the prevalence of each LB manifestation are different depending on the geographical areas. In this paper the differences between American and European, (in particular, Italian) clinical manifestations are discussed. Erythema migrans is the hallmark of early LB, present in about 80% of cases, and it is the most common lesion observed in our regions; acrodermatitis chronica atrophicans is milder in Italy than in Northern Europe and arthritis is less common in Italy than in the USA. In conclusion, at present the real incidence and prevalence of LB, in Italy is unknown and it cannot be estimated exactly because there is no mandatory reporting and standardized case definitions are not always in use.