Outbreak of alimentary tick-borne encephalitis in Podlaskie voivodeship, Poland

Abstract

Tick-borne encephalitis (TBE) virus remains one of the main etiological agents of central nervous system infections in Europe. The disease occurs endemically in Central and Eastern Europe, Southern part of Russia and Scandinavia. Between 2000 and 2015 there were 3 662 registered TBE cases in Poland and approximately 45% of them were reported in Podlaskie voivodeship. TBE typically develops as a result of being bitten by infected tick, however, it can also be a consequence of ingestion of unpasteurized milk from viremic animal. The aim of the article was to underline to the importance of TBE virus transmission via alimentary route and clinical description of four patients who developed TBE as a result of raw goat milk consumption. A retrospective analysis of documentation of four patients hospitalized in Observational-Infectious Department of Independent Public Healthcare Centre in Hajnówka and Department of Infectious Diseases and Neuroinfections at the Medical University of Bialystok from June 10th 2017 to July 11th 2017 due to alimentary TBE. Patients were between 24 and 36 years of age. They have consumed goat milk from the same source. None of the patients have been vaccinated against TBE virus. In all patients typical biphasic disease course with the presence of prodromal and neurological phase was observed. TBE was confirmed by demonstration of anti-TBE antibodies in serum and/or cerebrospinal fluid of patients. Diagnosis of TBE should be considered in every case of encephalitis in endemic areas. Due to the risk of TBE infection after consumption of unpasteurized milk from livestock, it is crucial to raise awareness of general population and farm owners about the possibility of TBE infection via alimentary route.