Comparison of the epidemiological and clinical features of tick-borne encephalitis in children and adults.

The aim of this prospective study was to compare epidemiological data and clinical features in children and adults with tick-borne encephalitis (TBE). Patients with aseptic meningitis diagnosed at the University Medical Centre, Department of Infectious Diseases, Ljubljana, Slovenia, from June to August 1997, in whom the diagnosis of TBE was ascertained by the presence of serum IgM antibodies against TBE virus, who were serologically negative for Borrelia burgdorferi sensu lato and had a negative PCR CSF result on enteroviral infection, were included in the study. Out of 213 patients with aseptic meningitis, 80 (37.56%) fulfilled inclusion criteria. There were 20 children and 60 adults. In both groups males predominated. Virtually all patients had headache and fever, and more than 50% suffered from vomiting. The majority of patients in both groups recalled a tick bite, had a biphasic course of the illness, and was found to have obviously expressed meningeal signs. In both groups the median CSF leukocyte count was somewhat lower than 100 x 10(6)/l with a predominance of lymphocytes. Children were more often given antibiotics during the initial phase of TBE than adults (p = 0.0095). Several other statistically significant distinctions (p < 0.05) were found including the frequency of fatigue, malaise, vertigo, photophobia, myalgias, arthralgias, as well as elevated CSF albumin and protein concentration, elevated albumin quotient and IgG quotient; all these findings were more often present in adults. In addition a longer duration of fever, more frequent need for anti-edematous treatment and longer hospitalization were found in adults. Direct comparison of clinical and epidemiological characteristics of TBE in children and adults revealed differences in several clinical and laboratory features and corroborates the previous conclusion that TBE in childhood is a milder illness than TBE in adults.