Disease causing pathogens are the first link in the chain of infection. Among these pathogens are a wide variety of viruses, bacteria, fungus, and protozoa. Pathogen-induced infections are major health burdens in Qatar and worldwide. This book tackles the epidemiology, prevalence and molecular diagnosis of major viral, bacterial, fungal, and protozoal diseases caused by pathogens in Qatar. It also highlights recent advances in microbiome science and its association with different health and disease conditions. Finally, the book highlights the important role of the Qatar Biobank as a major player in the enhancement of biomedical research in Qatar.