Autochthonous Cases of Tick-Borne Encephalitis, Belgium, 2020

Abstract

T ick-borne encephalitis (TBE) is a severe viral zoonosis caused by TBE virus (TBEV) (1). To date, confi rmed locally acquired human TBEV infections have not been reported in Belgium, although the most common vector, the tick Ixodes ricinus, is abundant in Belgium and seroprevalence studies have revealed the presence of TBEV antibodies in dogs, cattle, roe deer, and wild boar (2,3). We report 3 confi rmed autochthonous TBE cases, diagnosed at the National Reference Centre (NRC) for Arboviruses (Antwerp, Belgium) during summer 2020. The StudyA 48-year-old woman had muscle pain and an elevated body temperature 2 weeks after a tick bite on her right hip. She tested negative for coronavirus disease (COVID-19), and her general practitioner prescribed antimicrobial drugs. A few days later, the patient was hospitalized with asthenia, tremor, drowsiness, and fever. A neurologist determined signs of peripheral facial palsy with brachial weakness and nuchal rigidity. Cerebrospinal fl uid (CSF) showed an elevated leukocyte count (37 cells/µL; reference range 0-5 cells/µL). Borrelia serology and PCR results were negative. Magnetic resonance imaging

Spatiotemporal spread of tick-borne encephalitis in the EU/EEA, 2012 to 2020

“…This expansion has been previously described in recent scientific literature. While countries such as Austria, Czechia and Switzerland have been considered endemic for decades [1], the first human TBE cases were reported in Belgium, the Netherlands and the United Kingdom (UK) between 2016 and 2020 [23][24][25]. Furthermore, countries with known endemic regions such as Denmark, France and Germany have been reporting newly affected regions north and west of their traditional foci [26][27][28].…”

Comparison of Serological Methods for Tick-Borne Encephalitis Virus-Specific Antibody Detection in Wild Boar and Sheep: Impact of the Screening Approach on the Estimated Seroprevalence

“…Recently, our laboratory reported a TBEV seroprevalence of 0.42% in sheep and 9.27% in wild boar [ 15 ]. In 2020, for the first time, three autochthonous cases were identified in humans [ 17 ]. Ticks have also been screened, but so far, TBEV has not been detected [ 15 ].…”

First Expert Elicitation of Knowledge on Possible Drivers of Observed Increasing Human Cases of Tick-Borne Encephalitis in Europe

“…This driver was first implicated in TBEV emergence by [ 36 ], who suggested that increased unemployment and marginal employment in forests due to the socio-economic transition were driving an increase in human TBEV exposure across eastern Europe. Other studies have linked changing human behavior to new autochthonous cases of TBE in infected areas [ 30 , 36 , 43 ]. Preventive actions are mostly related to tick bite avoidance (wearing protective clothing such as long sleeve tops and long trousers tucked into socks or boots and using tick repellents on the skin and/or clothing) [ 35 ].…”

“…In Europe, TBE is endemic in several central, northern, and eastern countries. Some countries experienced novel autochthonous TBE in humans, like the Netherlands in 2016 [ 28 ], Belgium in 2018 and 2020 [ 29 , 30 ], and the United Kingdom in 2019 [ 31 ]. Since 2017, there has been a gradual increase in reported TBE cases in the European Union/European Economic Area (EU/EEA) (see also the atlas of diseases from ECDC at the following address: ; accessed on 15 March 2023).…”