Scientific Advances in the Diagnosis of Emerging and Reemerging Viral Human Pathogens

Despite scientific advances, the diagnosis of infectious diseases is primarily possible through vaccination and later by antibiotics. Emerging and reemerging pathologies are still considered to be dangerous to humanity because of the unique nature of these diseases: it is the encounter between two living organisms that have coexisted for millions of years within the people on the same planet without being previously recognized. These infectious agents, such as bacteria, viruses, fungi, or parasites, pose no threat to humans. In fact, only a few hundred are able to inflict damage to the human host. In addition, the spectrum of human disease caused by a particular pathogen varies considerably depending on the factors related to the ecological agent, the host, and the infectious agents. Several emerging or reemerging infectious agents are organisms that could be used in biological control. The differentiation of a natural epidemic from a bioterrorian event is based on several epidemiological indices as well as on the molecular characterization of the pathogen(s) involved. The role of pathologists is indeed very important. It is in this context that this chapter aims to discuss the various scientific advances, particularly molecular, in terms of diagnosis of these diseases; the new discoveries in the role of nanotechnologies and nanobiosensors; and also the implication of biomarkers, especially microRNAs (miRNAs), since it was reported that a single miRNA has the ultimate capacity to target multiple genes simultaneously. In a viral infection context, miRNAs have been connected with the interplay between host and pathogen and occupy a major role in the host–parasite interaction and pathogenesis. It is in this context that various molecular and nanomethods for the detection of emerging viruses and experimental validation of miRNAs during quelling viruses target transcripts will be discussed in this chapter.