Objective To evaluate the epidemiology of infectious meningitis in children in a Lyme borreliosis (LB) endemic area, and to study how clinical and laboratory characteristics may distinguish between different types of childhood meningitis.

Design Retrospective, population based study.

Setting A paediatric department serving all children (62 000) in a costal LB endemic region of southwestern Norway.

Patients All children with cerebrospinal fluid pleocytosis aged 3 months to 14 years.

Main outcome measures Epidemiological, clinical and laboratory characteristics of different types of childhood meningitis.

Results Infectious meningitis was diagnosed in 211 children (annual incidence 38/100 000). Lyme meningitis (LM) was identified in 142 children (67%), non-Lyme aseptic meningitis in 46 children (22%) and bacterial meningitis in 23 children (11%). Age, month of admission and clinical and laboratory characteristics differed between the groups. An aetiological agent was found in 89% of children. The positive predictive value for having LM if the child had facial nerve palsy or head and/or neck stiffness (meningism) as the only symptom was 97% for both variables. Symptoms of cerebral involvement or signs of systemic inflammation were rare in children with LM compared to children non-Lyme aseptic meningitis.

Conclusion LM was diagnosed in two-thirds of children with infectious meningitis in this LB endemic area. Distinct clinical characteristics distinguished the majority of children with LM from children with non-Lyme aseptic meningitis and bacterial meningitis.