Evidence of tick-borne encephalitis virus neutralizing antibodies in Serbian individuals exposed to tick bites

Front Microbiol. 2023 Dec 12:14:1314538. doi: 10.3389/fmicb.2023.1314538. eCollection 2023.

Abstract

Introduction: Tick-borne encephalitis (TBE) is an emerging vector-borne and food-borne disease caused by the tick-borne encephalitis virus (TBEV; Orthoflavivirus encephalitidis), with a distribution spanning the Eurasian continent. Despite its significant public health impact in various European regions, TBE remains largely underdiagnosed in Serbia due to limited awareness and diagnostic challenges. In response to this, our study aimed to comprehensively assess TBEV exposure in individuals infested with ticks and to identify potential TBEV foci within Serbia.

Materials and methods: From 2019 to 2021, we conducted an observational study involving 450 patients who reported tick infestations.

Results: Our demographic analysis revealed a median age of 38 years, with a slight male predominance among the participants. We documented tick infestations in 38 municipalities across 14 districts of Serbia, with a notable concentration in proximity to Fruška Gora Mountain. The ticks most frequently removed were Ixodes ricinus, with nymphs and adult females being the predominant stages. On average, nymphs were removed after about 27.1 hours of feeding, while adult females remained attached for approximately 44.4 hours. Notably, we found age as a significant predictor of infestation time for both nymphs and adult females. Furthermore, we detected TBEV-neutralizing antibodies in 0.66% of the serum samples, shedding light on potential TBEV foci, particularly in Fruška Gora Mountain and other regions of Serbia.

Conclusion: Our study emphasizes the urgent need for active TBE surveillance programs, especially in areas suspected of hosting TBEV foci, in order to assess the true TBE burden, identify at-risk populations, and implement effective preventive measures.

Keywords: Serbia; TBEV; TBEV-neutralizing antibodies; seroprevalence; ticks.

Grants and funding

The author(s) declare financial support was received for the research, authorship, and/or publication of this article. The BSL3+ work at Institute of Microbiology and Immunology, Faculty of Medicine, University of Ljubljana was supported by Slovenian Research and Innovation Agency (grant number P3-0083), Network of Infrastructure Centers of the University of Ljubljana (MRIC-UL-IC-BSL3+), and the European Union’s Horizon 2020 research and innovation program—EVA GLOBAL project (Grant agreement no. 871029). The BSL2+ work at Pasteur Institute Novi Sad was supported by an independent medical grant from Pfizer. The funders had no role in the design of the study; in the collection, analyses or interpretation of data; in the writing of the manuscript or in the decision to publish the results.