Options for decentralized testing of suspected secondary outbreaks of foot-and-mouth disease.

This article reviews the options for use of virus detection techniques for decentralized testing of samples from suspected secondary outbreaks of foot-and-mouth disease (FMD). These options have been expanded by the advent of new tests including disposable lateral flow devices (LFDs) that detect viral proteins and portable RT-PCR equipment that detects viral RNA. LFDs have been developed with similar sensitivity to antigen detection ELISA but with the ability to provide a result 1-30 min after the addition of epithelium or vesicular fluid. Portable RT-PCR platforms are being developed that can detect FMD viral RNA in blood, epithelium or other materials with minimal sample processing and with high sensitivity, in as little as 60 min in some cases. These devices may be used on infected farms as pen-side tests, in regional, local or mobile laboratories, or in National Reference Laboratories (NRL). Advantages and disadvantages of different testing options are considered to inform decisions on the optimal strategies for different national circumstances. Issues include validation and quality control, containment needs, availability of test devices and reagents, the decision tree for declaring an outbreak, training issues and provision of samples for subsequent viral characterization. Tests to confirm the diagnosis of the index case of an outbreak of FMD should continue to be carried out in the NRL.