Outbreak investigation: how to prevent laboratory contamination during high-throughput testing

This is particularly important for outbreaks of highly contagious animal diseases. Efficient and correct testing as well as the reduction of technical breakdowns should be addressed by a laboratory contingency plan specially designed for the use of polymerase chain reactions (PCRs), i.e. PCR or reverse transcription PCR ([RT]-PCR) or the high-throughput quantitative real-time form of these tests([RT]-qPCR). Problems with contamination during outbreak investigations can negatively impact reliable diagnostics, and ultimately the eradication of the disease in the field. Therefore, well-defined standard procedures for preventing contamination are highly recommended, particularly in emergencies when a steep increase in the number of samples necessitates the use of additional, less-experienced laboratory support staff. In the context of an outbreak, the possible implementation of preclinical testing is an important point of discussion. Very sensitive methods, which are prone to contamination, are used for this type of testing, increasing the risk of false-positive results. Potential approaches to minimising contamination include standard protocols adapted for high-throughput analyses, different procedures for samples with an expected high or low viral load, and the prioritisation and treatment of samples with respect to epidemiological aspects (e.g. epidemic vs endemic situations). Although there may be pressure to perform outbreak investigations as soon as possible, the authors do not recommend preclinical testing in every case due to the severe consequences of false-positive results. Contingency plans should be discussed with the responsible authorities and communicated to relevant personnel before an outbreak occurs. The specific aim of this paper is the detailed description of solutions to prevent the laboratory contamination of samples and to avoid the generation of false-positive results.