Tick populations from endemic and non-endemic areas in Germany show differential susceptibility to TBEV

Abstract

Tick-borne encephalitis virus (TBEV) is endemic in twenty-seven European countries, transmitted via the bite of an infected tick. TBEV is the causative agent of one of the most important viral diseases of the central nervous system (CNS). In Germany, 890 human cases were registered between the years 2018–2019. The castor bean tick, Ixodes ricinus, is the TBEV vector with the highest importance in Central Europe, including Germany. Despite the nationwide distribution of this tick species, risk areas of TBEV are largely located in Southern Germany. To increase our understanding of TBEV-tick interactions, we collected ticks from different areas within Germany (Haselmühl/Bavaria, Hanover/Lower Saxony) and infected them via an in vitro feeding system. A TBEV isolate was obtained from an endemic focus in Haselmühl. In two experimental series conducted in 2018 and 2019, ticks sampled in Haselmühl (TBEV focus) showed higher artificial feeding rates, as well as higher TBEV infections rates than ticks from the non-endemic area (Hanover). Other than the tick origin, year and month of the infection experiment as well as co-infection with Borrelia spp., had a significant impact on TBEV Haselmühl infection rates. Taken together, these findings suggest that a specific adaptation of the tick populations to their respective TBEV virus isolates or vice versa, leads to higher TBEV infection rates in those ticks. Furthermore, co-infection with other tick-borne pathogens such as Borrelia spp. can lower TBEV infection rates in specific populations.

Evaluation of two artificial infection methods of live ticks as tools for studying interactions between tick-borne viruses and their tick vectors

“…Vector competence is genetically determined and could rely on a particular virus strain and on a particular arthropod geographical strain. This has been shown previously for other arboviruses such as TBEV, bluetongue, Rift Valley fever virus or chikungunya virus 45 – 50 . The I. ricinus ticks we used in our studies were from Slovakia.…”

A one health approach to investigating an outbreak of alimentary tick-borne encephalitis in a non-endemic area in France (Ain, Eastern France): a longitudinal serological study in livestock, detection in ticks, and the first TBE virus isolation and molecular characterization

“…We evaluated a minimal detection of infectious viral particle at 10 4 TCID50/mL of milk and 10 5 TCID50/ mL after dissolution of 2.5g of cheese. In ticks, the mean viral copy number lies between 2 × 10 2 to 4.8 x10 3 RNA copies per sample (Liebig, Boelke et al 2020, Liebig, Boelke et al 2021. Our data confirmed the high virus load detected in tank milk.…”

Using social media listening and data mining to understand travellers’ perspectives on travel disease risks and vaccine-related attitudes and behaviours

“…For example, several traveller personas in our study were concerned by tick-borne encephalitis in regions with no such risk and despite the disease being endemic in parts of Germany. 40 The global level of anxiety about endemic disease at travel destinations in our study differed by persona, and of note, the different personas were not anxious about the same diseases. Our results suggest a need to adapt discussions between healthcare professionals and travellers to focus on the diseases that are associated with anxiety for the different traveller profiles to reassure and vaccinate (or initiate appropriate prophylaxis) as required.…”