Virus infection terminology

A serious mental illness characterized by the presence of hallucinations, delusions, disorganized speech or thinking, a loss of contact with reality, and a noticeable deterioration of functioning in everyday life. One of the most basic units of biological classification, ranking just below the genus and comprising individuals or populations capable of interbreeding.

The male gamete, or sex cell, which carries the hereditary material of the male parent and unites with the female egg cell during sexual reproduction.

An infection caused by any one of several harmful species or subspecies of bacteria of the genus Staphylococcus. The process of destroying all forms of life, including infectious agents, from a surface, fluid, or biological medium with the use of heat, chemicals, irradiation, high pressure, filtration, or some combination of these methods. A poisonous substance, often a protein, produced by the metabolic processes of living cells or organisms that can cause disease if introduced into the body.

The area, sometimes referred to as an ecotone, encompassing the edges of two distinct ecosystems, such as the area where a forest intersects with grassland. An organism usually an arthropod such as a flea, mosquito, or tick that carries an infectious agent from one host to another. An infectious agent that is only capable of replicating itself inside the living cells of other organisms.

A special type of cell that works as part of the immune system to defend the body against disease and infection. The directing and coordinating authority for health within the United Nations system, responsible for providing leadership on global health matters, shaping the health research agenda, setting norms and standards, articulating evidence-based policy options, providing technical support to countries and monitoring and assessing health trends.

A broad group of microscopic fungi that includes harmless forms of yeast used in baking and alcoholic fermentation as well as pathogenic species that can cause disease. Our bodies contain at least 10 times more bacterial cells than human cells. The National Academies. Adaptive Mutation A mechanism through which certain cells can increase the rate in which genetic mutations occur, often in response to stress. Anemia A condition in which there is a deficit in the number of healthy red blood cells in the blood, resulting in fatigue and feelings of weakness.

Antibiotic Resistance The process through which pathogenic microorganisms, by way of genetic mutation, develop the ability to withstand exposure to the drugs that had once been successful in eradicating them. Antibiotics A class of drugs used to kill or inhibit the growth of disease-causing microorganisms. Antibodies A class of drugs used to kill or inhibit the growth of disease-causing microorganisms. Autoimmune Disease An umbrella term for a range of conditions in which the immune system mistakenly attacks healthy tissue in the body.

Bacilli A taxonomic class of bacteria. Bacteria A large group of unicellular microorganisms that lack a cell nucleus. Beta-lactam Antibiotics One of several families of antibiotics, including penicillins, cephalosporins, carbapenems, and monobactams, containing a molecular ring-shaped structure made up of three carbon atoms and one nitrogen atom. Biological Agent Terrorism A bacterium, virus, or other biological toxin used in bioterrorism or biological warfare.

Bioterrorism The deliberate release of a virus, bacterium, or other biological agent to cause illness and death in people, animals, or plants. Bioweapon A bacterium, virus, or other biological toxin used in bioterrorism or biological warfare. Bronchial Tubes Large tubes that carry air into smaller branches of the lungs after the air has passed through the mouth, nasal passages, and windpipe.

Cancer A class of diseases in which abnormal cells divide without control and are able to invade healthy tissues in various parts of the body. Cell The smallest unit of living matter capable of functioning independently. Cell Membrane A semipermeable barrier that separates the interior of a cell from the external environment. Chromosome An organized structure of DNA and proteins within the nucleus of a cell that contains many genes.

Chronic Disease Any disease that is long lasting 3 months or more or recurrent—as opposed to an acute disease—and cannot be prevented by a vaccine or cured by medication. Cirrhosis A condition caused by chronic liver disease characterized by the development of scar tissue leading to a loss of liver function. Climate Change The process of shifting from one prevailing state in regional or global climate to another.

Contagion A general term for any disease-causing infectious agent spread by direct or indirect contact. Cytokine A type of protein secreted by cells in the immune system that carries signals that facilitate cell-to-cell communication and help regulate the way the immune system responds to inflammation and infection. Disease Any abnormal condition that affects all or part of an organism, resulting in symptoms such as pain or loss of function.

DNA Short for deoxyribonucleic acid, DNA is any of the nucleic acids that contain the genetic instructions necessary for the development and functioning of all living organisms as well as some viruses. No matter the shape, all viruses consist of genetic material DNA or RNA and have an outer protein shell, known as a capsid. There are two processes used by viruses to replicate: the lytic cycle and lysogenic cycle. Some viruses reproduce using both methods, while others only use the lytic cycle.

In the lytic cycle, the virus attaches to the host cell and injects its DNA. Then fully formed viruses assemble. These viruses break, or lyse, the cell and spread to other cells to continue the cycle. Like the lytic cycle, in the lysogenic cycle the virus attaches to the host cell and injects its DNA.

In humans, viruses can cause many diseases. For example, the flu is caused by the influenza virus. Typically, viruses cause an immune response in the host, and this kills the virus. However, some viruses are not successfully treated by the immune system, such as human immunodeficiency virus, or HIV. This leads to a more chronic infection that is difficult or impossible to cure; often only the symptoms can be treated.

Unlike bacterial infections, antibiotics are ineffective at treating viral infections. Viral infections are best prevented by vaccines, though antiviral drugs can treat some viral infections. Most antiviral drugs work by interfering with viral replication. Some of these drugs stop DNA synthesis, preventing the virus from replicating.

Although viruses can have devastating health consequences, they also have important technological applications. Viruses are particularly vital to gene therapy. Because some viruses incorporate their DNA into host DNA, they can be genetically modified to carry genes that would benefit the host.

Some viruses can even be engineered to reproduce in cancer cells and trigger the immune system to kill those harmful cells. Although this is still an emerging field of research, it gives viruses the potential to one day do more good than harm.

Antibiotics do not stop viruses. Also called the flu. The audio, illustrations, photos, and videos are credited beneath the media asset, except for promotional images, which generally link to another page that contains the media credit. Your immune system may be able to fight it off.

For most viral infections, treatments can only help with symptoms while you wait for your immune system to fight off the virus. Antibiotics do not work for viral infections. There are antiviral medicines to treat some viral infections. Vaccines can help prevent you from getting many viral diseases. The information on this site should not be used as a substitute for professional medical care or advice.

Contact a health care provider if you have questions about your health. Viral Infections. Learn More Related Issues Specifics. See, Play and Learn Images.