Bluetongue: control, surveillance and safe movement of animals

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Article
bluetongue, vaccination, surveillance, vector, Culicoides, insecticides
First published in the EFSA Journal
8 March 2017
Adopted
18 January 2017
Type
Opinion of the Scientific Committee/Scientific Panel
Abstract

The performance of different bluetongue control measures related to both vaccination and protection from bluetongue virus (BTV) vectors was assessed. By means of a mathematical model, it was concluded that when vaccination is applied on 95% of animals even for 3 years, bluetongue cannot be eradicated and is able to re-emerge. Only after 5 years of vaccination, the infection may be close to the eradication levels. In the absence of vaccination, the disease can persist for several years, reaching an endemic condition with low level of prevalence of infection. Among the mechanisms for bluetongue persistence, the persistence in the wildlife, the transplacental transmission in the host, the duration of viraemia and the possible vertical transmission in vectors were assessed. The criteria of the current surveillance scheme in place in the EU for demonstration of the virus absence need revision, because it was highlighted that under the current surveillance policy bluetongue circulation might occur undetected. For the safe movement of animals, newborn ruminants from vaccinated mothers with neutralising antibodies can be considered protected against infection, although a protective titre threshold cannot be identified. The presence of colostral antibodies interferes with the vaccine immunisation in the newborn for more than 3 months after birth, whereas the minimum time after vaccination of animal to be considered immune can be up to 48 days. The knowledge about vectors ecology, mechanisms of over-wintering and criteria for the seasonally vector-free period was updated. Some Culicoides species are active throughout the year and an absolute vector-free period may not exist at least in some areas in Europe. To date, there is no evidence that the use of insecticides and repellents reduce the transmission of BTV in the field, although this may reduce host/vector contact. By only using pour-on insecticides, protection of animals is lower than the one provided by vector-proof establishments.

Panel members at the time of adoption
Miguel Angel Miranda, Jan Arend Stegeman, Dominique Bicout, Anette Botner, Andrew Butterworth, Paolo Calistri, Klaus Depner, Sandra Edwards, Bruno Garin-Bastuji, Margaret, Good, Christian Gortazar Schmidt, Virginie Michel, Simon More, Mohan Raj, Søren Saxmose Nielsen, Lisa Sihvonen, Hans Spoolder, Hans H. Thulke, Antonio Velarde, Preben Willeberg and Christoph Winckler.
Panel on Animal Health and Welfare
doi
10.2903/j.efsa.2017.4698
EFSA Journal 2017;15(3):4698 [126 pp.].
Question Number
On request from
European Commission
Print on demand
Number of Pages
126