Low prevalence of tick-borne encephalitis virus antibodies in Norwegian blood donors

Abstract

Background: Tick-borne encephalitis (TBE) constitutes a public health concern in Europe. Certain coastal municipalities in southern Norway are considered TBE risk areas and in the last two years, there have been increasing numbers of TBE cases. Since the majority of infections are claimed to be asymptomatic, the aim of the current study was to assess the seroprevalence of antibodies to tick-borne encephalitis virus (TBEV) among unvaccinated adults living in a TBE endemic area in Norway.Methods: One thousand one hundred and twenty-three blood donors living in Vestfold and Telemark county were included and associated sera were analysed for TBEV IgG antibodies. Information regarding tick bites, previous flavivirus exposure and knowledge regarding TBE and TBE prevention were obtained through a questionnaire.Results: Fifty-eight samples were reactive by ELISA, of which 21 (36.2%) were confirmed by a TBEV-specific serum neutralization test. Of the 21 blood donors with neutralizing TBEV antibodies detected, 17 reported previous TBE vaccination. Thus, only four blood donors (0.4%) had TBEV neutralizing antibodies consistent with previously undergone TBEV infection. Regarding TBE awareness, half of the blood donors were familiar with TBE, but only 35% were aware of a preventive TBE vaccine.Conclusions: Our study indicates low prevalence of subclinical TBEV infections among blood donors living in Vestfold and Telemark county and there is a lack of awareness among general public.

Seroprevalence Rates against West Nile, Usutu, and Tick-Borne Encephalitis Viruses in Blood-Donors from North-Western Romania

“…The present study depicts a rather low seroprevalence rate regarding the TBEV in the assessed samples compared to countries where it is considered endemic [57][58][59], yet it is comparable with results obtained by Christova et al (2017) in Bulgaria (0.6%) [60]. Low seroprevalence rates were also reported in studies conducted on healthy blood donors in Norway (0.65, 0.4%) [61,62].…”

Seroprevalence of tick-borne diseases in the Northwest Federal District of the Russian Federation

“…Similar results were obtained from a survey of healthy donors in other areas (Vestfold and Telemark counties) in Norway. Only 0.4% of them had antibodies to TBEV [36,38].…”

Prevalence of tick‐borne encephalitis virus in questing Ixodes ricinus nymphs in southern Scandinavia and the possible influence of meteorological factors

“…meningoencephalitis and meningoencephalomyelitis (Kaiser, 1999); however, infections with TBEV-Eu are often reported to be asymptomatic (Gritsun et al, 2003;Larsen et al, 2014;Marvik et al, 2021;Svensson et al, 2021;Thortveit et al, 2020).TBE has been a notifiable disease in Sweden andNorway since 1969 and1994, respec-tively, but is not at present notifiable in Denmark.…”

“…TBEV has also been detected in raw milk from cows and sheep (Cisak et al, 2010; Paulsen et al, 2019; Wallenhammar et al, 2020). TBEV infection may vary from being asymptomatic to fatal meningitis, encephalitis, meningoencephalitis and meningoencephalomyelitis (Kaiser, 1999); however, infections with TBEV‐Eu are often reported to be asymptomatic (Gritsun et al, 2003; Larsen et al, 2014; Marvik et al, 2021; Svensson et al, 2021; Thortveit et al, 2020). TBE has been a notifiable disease in Sweden and Norway since 1969 and 1994, respectively, but is not at present notifiable in Denmark.…”