A Retrospective Analysis of Tick-borne Encephalitis in Children Treated in Kaunas Hospital During 2012 to 2019

Background: Lithuania has the highest tick-borne encephalitis (TBE) rates in Europe. Although TBE incidence in children is lower, it may still cause long-term consequences. So far pediatric epidemiological and clinical characteristics of TBE in Lithuania were not described. Methods: We performed a retrospective analysis of 87 cases of children who were hospitalized for TBE in Kaunas Hospital of the Lithuanian University of Health Sciences from 2012 to 2019. Each case was identified with neurological symptoms and positive serological tests. Results: Around half of the children (50.6%) reported having a tick bite, whereas 6.9% stated having exposure to unpasteurized milk. Biphasic course of the disease occurred in 70.1% of the cases. The most common clinical symptoms were headache (100%), fever (100%), nausea (85.1%), vomiting (78.2%), drowsiness (67.8%) and general weakness (66.7%). Meningeal symptoms were present in 93.1% of the cases, and 93.1% of the children had at least one focal neurological sign (tremor 82.3%, impaired balance 73.6%). Isolated meningitis was diagnosed in 57.5%, meningoencephalitis in 41.4% and meningoencephalomyelitis in 1.1% of the cases. Majority of younger children (1-8 years old) had meningitis (77.3%), whereas 49.2% of older children (9-17 years old) had more severe forms of TBE. Cerebrospinal fluid pleocytosis was found in 94.3% of cases (average white blood cell count: 111.7 per mu L, protein: 0.5 g/L). Higher levels of cerebrospinal fluid protein were associated with more severe forms of TBE and older age. Duration of the symptomatic disease lasted approximate to 11 days. Early residual signs were observed in 75.9% of all cases. Conclusions: The epidemiological and clinical characteristics of TBE in children in Lithuania are similar to those described in other countries. Only half of the subjects reported having a tick bite. Younger children tend to suffer from meningoencephalitis and meningoencephalomyelitis less frequently than elder ones. Focal neurological signs were commonly observed. Majority of children had lasting symptoms of TBE upon discharge from the hospital.