Viral diseases: Introduction. A viral infection is any type of illness or disease caused by a virus, a type of microbe. Microbes are tiny organisms that cannot be seen without a microscope and include bacteria, fungi, and some parasites, as well as viruses.iral diseases: Introduction. A viral infection is any type of illness or disease caused by a virus, a type of microbe. Microbes are tiny organisms that cannot be seen without a microscope and include bacteria, fungi, and some parasites, as well as viruses.
OPTAR stands for Operating/Operational Target. Operating Targets. Operations, Planning, Training and Resource Support Services. Oceanside Photo & Telescope Astronomical Society (San Diego County, CA) Operational Tasking. Operational Tasking Data Link. Operational Tasking Nuclear. Occasional Papers in Translation and Textlinguistics.
Opthalmology The ability of the eye to adjust to variations in light intensity Psychology The fitting of behavior to the environment by modifying one's impulses, emotions, or attitudes. See Social adaptation.