Operational TBE incidence forecasts for Austria, Germany, and Switzerland 2019-2021

In spring 2019, forecasts of the incidence of tick-borne encephalitis (TBE) for the next 2 years, i.e. 2019 and 2020, were made for the first time. For this purpose, negative binomial regression models with 4-5 predictors were fitted to the time series of annual human TBE incidences from Austria, Germany, and Switzerland. The most important predictor for TBE incidences is the fructification index of the European beech (Fagus sylvatica) 2 years prior as a proxi for the intensity of the TBE virus transmission cycle. These forecasts were repeated in spring 2020 after the updated predictors and the confirmed TBE cases for 2019 became available. Forecasting TBE incidences for 2020 and 2021 results in 156 ± 19 and 131 ± 23 TBE cases for Austria, 663 ± 95 and 543 ± 112 TBE cases for Germany as well as 472 ± 56 and 350 ± 62 TBE cases for Switzerland. The newly implemented operational TBE forecasts will be verified every year with confirmed TBE cases. An initial verification for 2019 demonstrates the high reliability of the forecasts.