Clinical features of Lyme borreliosis in the middle Urals and distribution of Borrelia burgdorferi sensu lato species in local Ixodes persulcatus ticks.

From 1991 to 1993, we investigated the clinical features of Lyme borreliosis (LB) in 864 patients from the Sverdlovsk region (population 4.5 million) in the middle Urals. Ixodes persulcatus ticks were collected in the vicinity of Yekaterinburg to determine the presence of Borrelia burgdorferi sensu lato species. From 1991 to 1993, the number of patients with LB increased from 91 to 320 and 453, respectively. Nearly all LB patients (97%) recalled a tick bite and the first signs of LB developed between May and August. Erythema migrans (EM) was seen in 820 patients (94.9%) and fever was common (44.6%). Neuroborreliosis, mainly radiculoneuritis, was found in 154 patients (17.8%), secondary erythema was seen in 53 patients, and Lyme arthritis (LA) was diagnosed in 35 patients. Carditis was rare and acordermatitis chronica atrophicans (ACA) was not seen. Only 44 patients developed one or more symptoms of LB without a preceding EM. Few patients were seropositive for tick-borne encaphalitis. Borrelial DNA was detected in 67% of I. persulcatus ticks. Infected ticks carried predominantly Borrelia garinii or Borrelia afzelii, mixed infections of both species were common. Borrelia valaisiana was detected once, and B. burgdorferi sensu stricto was not found. Although the course of LB in the middle Urals in comparable to that of European LB, several discrepancies were noted. LB patients often recall tick bites, fever is common, LA is mild and ACA is absent.