The incidence of
Lyme borreliosis (LB) was studied prospectively in 49 children (< 17 years of age) with 50 episodes of acute FP. In addition, 43 children with a history of FP (average follow-up of 5.2 y) were studied retrospectively for the outcome of FP and for the symptoms and signs of late LB. In the prospective study, 17 (34%) patients with FP proved to have acute LB. They all received antibiotic treatment and their FP had a favourable outcome. In the retrospective study the patients had had FP before the diagnostic tests for LB were available. Thus, none of the 43 patients had been diagnosed to have, or treated for, LB. The outcome of their FP had generally been favourable. None of them had any signs of late LB at the follow-up visit. Our results indicate that LB is a frequent cause of acute paediatric FP in an endemic area. In addition our data suggests that FP caused by LB in children has a favourable prognosis, even when left untreated.