Chapter 23 : Molecular Diagnostic Assays for the Detection and Control of Zoonotic Diseases

Abstract:

Zoonotic pathogens, those that are naturally transmissible from animals to humans, are important causes of morbidity and mortality in humans, with outcomes ranging from mild to fatal and occurrences from sporadic disease to pandemics. These pathogens have had profound impacts on human health throughout recorded history and will continue to pose challenges, as the majority of emerging pathogens are zoonotic (1). Continued encroachment of humans into previously undeveloped regions, concentration of human and animal populations from urban sprawl, expanded animal and vector ranges resulting from climate change, increasingly mobile animal populations, and rapid international movement of animal-based foods facilitate the emergence and rapid dissemination of zoonotic pathogens. Recent years have been accompanied by dramatic instances of newly identified zoonotic pathogens (e.g., severe acute respiratory syndrome coronavirus [2], Middle East respiratory syndrome coronavirus [3, 4], Hendra virus [5]), marked range changes in known pathogens (e.g., West Nile virus in North America [6]), and new variants of well-known pathogens (e.g., H1N1 pandemic influenza A [7]). Potential new clinical roles for known pathogens have also been identified, such as the recent association of Bartonella henselae with some neurocognitive disorders (8). The close relationship between animals and humans has also been reflected in the identification of interspecies transmission of important pathogens such as methicillin-resistant Staphylococcus aureus (MRSA) (9) and extended-spectrum beta-lactamase-producing Enterobacteriaceae (10, 11). At the same time, “traditional” zoonotic pathogens such as rabies virus, influenza A, Salmonella, Campylobacter, and Coxiella burnetii continue to pose tremendous challenges. While the overall impact of zoonotic diseases is not known (and virtually impossible to quantify), it is undeniable that diseases spread directly from animals, from animal products, and from animal contamination of the environment have a profound impact on human health and require substantial efforts for diagnosis, treatment, prevention, and control. All of those have a foundation in accurate and timely diagnostic testing, so it should be no surprise that molecular diagnostic testing is increasingly being used to identify zoonotic pathogens.