A microarray such as the LLMDA [19, 20] could be a useful tool in a number of ways. Since it enables simultaneous detection of viruses as well as bacteria, it could be useful in e.g. diagnosis of sexually transmitted diseases, or of respiratory illnesses with combined viral and bacterial components. Furthermore, many viruses cause symptoms that clinically are very similar, making it hard to choose the correct diagnostic analysis. In cases of clinical hypothesis failure, the microarray could be a useful tool for finding an etiologic agent in samples that are presumed negative or in samples with unknown etiology. Microarray could also play a dual role combining diagnostics and research, by being a suitable research tool for finding new pathogens. It could also be of great value for epidemiological surveillance, where clinically unimportant viruses or viruses with unknown consequence for the carrier (e.g. TTV, retroviruses or others) could be found, described and followed in both human and animal populations.