Unexpected TBEV Seropositivity in Serbian Patients Who Recovered from Viral Meningitis and Encephalitis

Ixodid ticks and zoonotic tick-borne pathogens of the Western Balkans

Ixodid ticks are distributed across all countries of the Western Balkans, with a high diversity of species. Many of these species serve as vectors of pathogens of veterinary and medical importance. Given the scattered data from Western Balkan countries, we have conducted a comprehensive review of available literature, including some historical data, with the aim to compile information about all recorded tick species and associated zoonotic pathogens in this region. Based on the collected data, the tick fauna of the Western Balkans encompasses 32 tick species belonging to five genera: Ixodes, Haemaphysalis, Dermacentor, Rhipicephalus and Hyalomma. A range of pathogens responsible for human diseases has also been documented, including viruses, bacteria and parasites. In this review, we emphasize the necessity for integrated surveillance and reporting, urging authorities to foster research by providing financial support. Additionally, international and interdisciplinary collaborations should be encouraged that include the exchange of expertise, experiences and resources. The present collaborative effort can effectively address gaps in our knowledge of ticks and tick-borne diseases.

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

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.

Tick-Borne Encephalitis Virus and Borrelia burgdorferi Seroprevalence in Balkan Tick-Infested Individuals: A Two-Centre Study

Lyme borreliosis (LB) and tick-borne encephalitis (TBE) are important tick-borne diseases in Europe. This study aimed to investigate the seroreactivity against Borrelia burgdorferi and TBE virus (TBEV) in tick-infested individuals in North Macedonia and Serbia. Serum samples were collected from tick-infested individuals and from healthy individuals in the same regions. Samples were tested for anti-Borrelia IgG reactivity and TBEV-neutralizing antibodies. Results showed higher seroreactivity against Borrelia antigens in patients and healthy donors from Novi Sad compared to those from the Skopje region. However, there was no statistically significant difference between tick-infested patients and healthy donors within each region. No TBEV-neutralizing antibodies were detected in participants from Novi Sad or in the control groups, except for one person from North Macedonia who had a moderate TBEV-neutralizing reaction. The study highlights the need for improved surveillance and diagnostic capabilities for LB and TBE in these regions. It also suggests the potential existence of TBEV foci in North Macedonia. The findings provide a complementary understanding of the LB and TBE epidemiology in the studied regions; however, further research is needed to investigate the presence and distribution of Borrelia spp. and TBEV in ticks to assess the significance of detected seroreactivity.

Tick-borne encephalitis in pediatrics: An often overlooked diagnosis

Tick-borne encephalitis (TBE) is a vector-borne disease caused by a flavivirus, the tick-borne encephalitis virus (TBEV), and transmitted by the bite of infected Ixodes ricinus ticks. The European subtype (TBEV-Eu) is endemic in 27 European countries. During the last decade, increased TBE incidence was observed in many countries, including some of those believed to be of low endemicity/devoid of TBEV circulation. However, data dealing with TBE in children are far less profuse than with adults. Historically, children are known to have mild TBEV infection with favorable outcomes. That said, recent case reports and observational studies on pediatric cohorts have challenged this point of view. Like adults, children may present severe forms and fail to completely recover following TBE infection, at times leading to long-term cognitive impairment. In this review, we comprehensively describe the incidence, exposure factors, and transmission routes of TBEV in children, as well as the clinical and biological manifestations of TBE and imaging findings in this population. We also harness new data on long-term outcomes and sequelae in pediatric cohorts. Finally, we provide an overview of vaccination recommendations for children in European countries.

Fatal Case of Imported Tick-Borne Encephalitis in South Serbia

Tick-borne encephalitis (TBE) is vaccine-preventable neglected zoonotic neuroinvasive disease, caused by tick-borne encephalitis virus (TBEV). Many of the Central and Eastern European countries are affected by TBE, which is often poorly perceived by tourists visiting endemic territories. Here we are reporting a fatal case of imported TBE in Serbian resident who was exposed to a tick bite during a visit to Switzerland.

Recommendations to Improve Tick-Borne Encephalitis Surveillance and Vaccine Uptake in Europe

There has been an increase in reported TBE cases in Europe since 2015, reaching a peak in some countries in 2020, highlighting the need for better management of TBE risk in Europe. TBE surveillance is currently limited, in part, due to varying diagnostic guidelines, access to testing, and awareness of TBE. Consequently, TBE prevalence is underestimated and vaccination recommendations inadequate. TBE vaccine uptake is unsatisfactory in many TBE-endemic European countries. This review summarizes the findings of a scientific workshop of experts to improve TBE surveillance and vaccine uptake in Europe. Strategies to improve TBE surveillance and vaccine uptake should focus on: aligning diagnostic criteria and testing across Europe; expanding current vaccine recommendations and reducing their complexity; and increasing public education of the potential risks posed by TBEV infection.