5.5.8 How can the seroconversion in foxes be determined?

The determination of seroconversion rates in the fox population after vaccination is based on the detection of rabies specific antibodies. By definition, seroconversion rate is the percentage of target animals having specific antibodies (humoral immune response) against RABV as a result of vaccination and should not be mixed up with herd immunity (see section 5.5.9). Rabies-specific antibodies can be measured either using a serum neutralisation test (VNAs) or an enzyme-linked immunosorbent assay (ELISA; binding antibodies).

The determination of seroconversion is strongly influenced by the sensitivity and specificity of the serological test used and the quality of the sera. If the monitoring of ORV campaigns is based exclusively on determination of seroconversion, the vaccination coverage in red foxes will be underestimated, as a certain percentage of foxes (5-10%) that have consumed a vaccine bait will develop immunity that cannot be measured by any of the above mentioned serological tests.


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Version 1 - Last updated November 2012