Svensson et al.
A serosurvey of tick-borne encephalitis virus in Sweden: Different populations and geographical locations.
Vector Borne Zoon. Dis. 2021; 21:614-619. doi: 10.1089/vbz.2020.2763

Since the first TBE cases having been reported in Sweden in the 1950s in coastal areas near Stockholm, the annual number and geographical spread of TBE has significantly increased there. This is also true for the province of Skåne in southern Sweden. A study has been carried out to analyze the prevalence and levels of TBE antibodies in people living in rural areas of Skåne who had visited health care centers (group 1) and of people living in Skåne who self-reported to often get tick bites (group 2).

A total of 491 samples were anonymously collected from individuals belonging to group 1, of which 0.6% were IgM TBE positive and 5.4% were IgG TBE positive – with a range from 0% to 8.6% depending on the geographical regions where the people lived.

In group 2, the TBE vaccination coverage was 45% according to the study questionnaire. 28% of the individuals were TBE IgG positive with a medium ELISA titer of 55.5 RU/ml in the vaccinated group and 3.7 RU/ml in the unvaccinated group. In group 2, six individuals have been identified who had neutralizing TBE antibodies despite not having been vaccinated.

The authors concluded that different levels of TBE antibodies have been found in different geographical locations in southern Sweden. In addition, subclinical or misdiagnosed TBE cases have probably occurred in Skåne.

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