Viruses are small (10-100nm) that is one tenth of the size of a bacterium, in general can only be seen via electron microscope. These microorganisms infect humans, other animals, plants and bacteria and they can cause severe acute or intense oral, facial or systemic disease. The disease is manifested with signs and symptoms that lead to infection and illness. Viruses can be easily transmitted via various routes.
They consist of genetic material ( DNA or RNA) but never both, can be single or double stranded and can be of circular or linear form. Viruses cannot live on their own, they need a host cellular activity to replicate or survive. The viral genetic material is surrounded by a coat made of proteins called caspids, these create a structure called nucleocaspid. This whole structure can be “naked or “enveloped”, the virus is to be enveloped if the nucleocaspid has a coat or sheath derived from the actual host cell membrane. Viral composition is arranged in symmetric forms, either icosahedral (cubic) and helical (rod shape).
Viral classification is based on either its genetic material (DNA OR RNA), morphology or by host’s immunological response to the virus. A virus cannot live on its own, it can only survive inside the host or infected cell. In order to replicate, the virus must first attach to the receptors on the host’s cells, followed by penetration into the host cell. Once inside the cell, the viral particle becomes part of the cellular activity and so it transforms and releases its genetic material using the cell’s activity. As the viral genetic material gets into the cell, it directs the host’s cell to produce more viral material, (viral DNA replicates in cell’s nucleus, while viral RNA replicates in the cell membrane of the host’s cell). New viral forms are formed then release out of the host’s cell, then the host’s cell dies or gets destroyed since the virus inactivated normal cell activity.
Healthy individuals with normal or properly functioning immune systems, intact skin, good oral health, healthy bodily functions and with current immunization schedules can avoid viral infections. Viruses are opportunistic microorganisms who take advantage of weaken immune systems. The type of severity of disease symptoms depend on location and type of cells infected, the quantity of the virus, the body’s or host’s immune response to the infection and tissue damage, these determine the severity of the disease.
Viruses can enter via respiratory tract (oral, inhalation of aerosols, droplets) gastrointestinal (stomach, intestines), genital tract or by penetrating the skin. Once inside the body, viruses may produce symptoms at the location of infection or can replicate at he location of infection and then travel to nearby areas or distant organs or systems to produce disease.
Viruses cannot replicate outside the infected host, and generally are only seen under the electron microscope. However, there are viral diagnosis that rely on virus isolation in living systems, viral antigen detection, viral serology (study of the response in composition of blood to the viral particle) and molecular biology using molecular probes. Light microscope can also be used using viral infected cells scraped from an infected lesion and stained with specific stains to see or study inclusions or abnormal structures that can appear within the infected cell.
Viruses are parasites that used the host’s cells to copy themselves, viruses causing human disease are quite numerous and some are very familiar to us. Most viruses have limited host range and do not survive long outside a the host’s body. As viruses change and new viruses surface in response to environmental pressures, at our dental practice, we thrive in staying informed and follow strict OSHA Personal Protective Equipment standards, OSHA blood born pathogen standards, California Division of Occupational Safety and Health Standards, general environmental controls and many more safety precautions and engineering controls to prevent the transmission of pathogens in our environment. The safety of our patients is paramount.
