Abstract

Tick-borne encephalitis (TBE) is one of the most severe human tick-borne diseases in Europe. It is caused by the tick-borne encephalitis virus (TBEV), which is transmitted to humans mainly via bites of Ixodes ricinus or I. persulcatus ticks. The geographical distribution and abundance of I. ricinus is expanding in Sweden as has the number of reported human TBE cases. In addition to tick bites, alimentary TBEV infection has also been reported after consumption of unpasteurized dairy products. So far, no alimentary TBEV infection has been reported in Sweden, but knowledge about its prevalence in Swedish ruminants is scarce. In the present study, a total of 122 bulk tank milk samples and 304 individual milk samples (including 8 colostrum samples) were collected from dairy farms (n = 102) in Sweden. All samples were analysed for the presence of TBEV antibodies by ELISA test and immunoblotting. Participating farmers received a questionnaire about milk production, pasteurization, tick prophylaxis used on animals, tick-borne diseases, and TBE vaccination status. We detected specific anti-TBEV antibodies, i.e., either positive (>126 Vienna Units per ml, VIEU/ml) or borderline (63-126 VIEU/ml) in bulk tank milk from 20 of the 102 farms. Individual milk samples (including colostrum samples) from these 20 farms were therefore collected for further analysis. Our results revealed important information for detection of emerging TBE risk areas. Factors such as consumption of unpasteurized milk, limited use of tick prophylaxis on animals and a moderate coverage of human TBE vaccination, may be risk factors for alimentary TBEV infection in Sweden.

Keywords

Dairy animals; Bulk tank milk; Tick-borne encephalitis; Tick-borne encephalitis virus; Unpasteurized milk; Antibody detection

Published in

Comparative Immunology, Microbiology and Infectious Diseases
2023, Volume: 95, article number: 101958
Publisher: ELSEVIER SCI LTD

SLU Authors

• Hanberger, Alexander

  • Department of Animal Biosciences, Swedish University of Agricultural Sciences
    

• Albihn, Ann

  • Department of Animal Biosciences, Swedish University of Agricultural Sciences
    
  • National Veterinary Institute (SVA)

Sustainable Development Goals

Ensure healthy lives and promote well-being for all at all ages


UKÄ Subject classification

Microbiology
Animal and Dairy Science


Publication identifier

DOI: https://doi.org/10.1016/j.cimid.2023.101958

Permanent link to this page (URI)

https://res.slu.se/id/publ/122446