Autochthonous Tick-Borne Encephalitis Virus-Seropositive Cattle in Belgium: A Risk-Based Targeted Serological Survey

Abstract

The risk of tick-borne encephalitis virus (TBEV) introduction into Belgium remains high, and the presence of infected wildlife in Belgium is suspected. Domestic animals can serve as excellent sentinels for TBEV surveillance to install an early warning surveillance component for this emerging zoonotic disease of public health importance. In a targeted, risk-based and cross-sectional sampling design, serological screening was performed on Belgian cattle (n=650), selected from the 2010 Belgian national cattle surveillance serum bank. All samples were subjected to a gold standard TBEV seroneutralization test (SNT), based on the rapid fluorescent focus inhibition test (RFFIT) protocol. Seventeen bovines were seropositive (titer >1/15) and six had borderline results (1/10 < titer < 1/15). The accuracy of the RFFIT-SNT was confirmed in a mouse inoculation test. The overall bovine TBEV seroprevalence in the targeted area was estimated between 2.61% and 4.29%. This confirms for the first time the presence of infected foci in Belgium. Further surveillance in cattle, other sentinels, ticks, and humans at risk is recommended to further determine the location and size of endemic foci and the risk for public health.

First TBEV serological screening in Flemish wild boar

“…Immunoglobulin of subtype G (IgG) antibodies were first detected by a commercial veterinary TBEV-ELISA (Immunozym FSME/TBE IgG All-Species-ELISA ® , Progen Biotechnik GmbH, Germany). Then, neutralising TBEV-specific antibodies were titrated for all samples using a seroneutralisation test (SNT) and two cut-off titres (1/10–1/15) ( 3 , 8 ). This test is considered to be the gold standard for medical and veterinary diagnosis of TBE ( 9 , 10 ).…”

Tick-borne encephalitis in Europe, 2012 to 2016

“…More recently, some countries, e.g. Belgium and the Netherlands, reported possible new endemic foci having found antibodies to the TBE virus in roe deer and cattle [ 14 , 15 ] and in 2016, the Netherlands reported their first locally-acquired human case [ 16 ]. The mapping of endemic foci is essential to make recommendations for vaccination programme and travel advice [ 17 ].…”

Tick-Borne Encephalitis Virus in Ticks and Roe Deer, the Netherlands

“…Expansion of TBEV subtypes has been reported ( 4 ). Reports of TBEV-neutralizing antibodies in wildlife and cattle in Belgium prompted us to reinvestigate the presence of TBEV in the Netherlands ( 5 , 6 ). …”