Rabies prevention: the role of serology in parenteral vaccination of companion animals and livestock.

Rabies virus (RABV)-specific antibodies generated in response to rabies vaccination provide the basis for the establishment of rabies protection and hence rabies control and prevention. Rabies serology is the primary and most appropriate way to determine vaccination efficacy. Various immunological methods, such as serum neutralisation, enzyme-linked immunosorbent assay, the indirect fluorescent antibody test and immunochromatographic (or lateral flow) assay can detect and measure these antibodies. These methods range from complex to simple and from highly precise to approximate. Rabies serology interpretation, cut-off levels and method limitations are important considerations that oftentimes are overlooked when evaluating the results of tests that measure the immune response to rabies vaccination or RABV antigen exposure. In addition, a meaningful result may depend on the timing of obtaining the samples. Practical issues such as the costs of testing and accessibility of test reagents or facilities play an increasingly important role in the success of rabies elimination efforts in developing areas. The discovery of new lyssaviruses in recent years means that the rabies vaccines currently in use should be evaluated to determine whether or not they confer protection against these viruses. Methods that can be adapted for the measurement of RABV-specific antibodies are needed. Whether used for diagnosis, serosurveillance, or determination of individual or group vaccine response, rabies serology has a great impact on rabies control and prevention efforts. It is critical, therefore, that not only does the method employed generate results that are applicable, but that these results are interpreted correctly. To ensure that this is the case, it is crucial to know exactly what the test was designed to measure and to understand its limitations.