Glossary of Flu and Influenza Terms

Acute Care- Services provided by physicians and other health professionals and staff in the community and in hospitals, including emergency, general medical and surgical, psychiatric, obstetric and diagnostic services.

Airborne Transmission- Refers to dissemination of microorganisms by aerosolization. Organisms are contained in droplet nuclei or in dust particles containing skin cell slough/debris that remains suspended in the air for long periods of time. Such microorganisms are widely dispersed by air currents.

Airborne Precautions- Precautions taken to prevent and control the spread of infection for organisms spread by airborne transmission.

Allergic reaction- The hypersensitive response of the immune system of an allergic individual to a substance.

Allergy- A misguided reaction to foreign substances by the immune system , the body system of defense against foreign invaders, particularly pathogens. The allergic reaction is misguided in that these foreign substances are usually harmless.

Amantadine- An antiviral agent indicated in adults and children >1 year for the treatment of illness due to influenza and for prophylaxis following exposure to influenza type A viruses. It has no effect against the influenza type B virus.

Antibiotic- A substance produced by bacteria or fungi that destroys or prevents the growth of other bacteria and fungi.

Antibiotic resistance- Occurs when bacteria or other microbes that cause disease evolve into forms that can no longer be killed by antibiotics. It is the reason people are not given antibiotics as readily as in the past.

Antibody- A protein produced by the body's immune system that recognizes and helps fight infections and other foreign substances in the body. When your body is infected with a particular strain of influenza, the immune system makes antibodies that are specific to that strain.

Antigenic Drift- A gradual change of the hemagglutinin or neuraminidase proteins on the surface of a particular strain of influenza virus occurring in response to host antibodies in humans who have been exposed to it. It occurs on an ongoing basis in both type A and type B influenza strains and necessitates ongoing changes in influenza vaccines.

Antigenic Shift- The movement of a type A influenza virus strain from other species into humans. The novel strain emerges by reassortment with circulating human influenza strains or by infecting humans directly. Because they flourish in the face of global susceptibility, viruses that have undergone antigenic shift usually create pandemics.

Antisense RNA- Negative sense RNA is the kind of RNA that is the genetic blueprint of the influenza virus. RNA, like DNA, carries genetic information in a sequence of three letters (the genetic code). In our bodies, DNA is double-stranded, with each strand a 'code mirror image' of the other. Thus when the cell replicates, the two strands separate and each makes a mirror image copy so the result is two new double-strands just like the first one. In the influenza virus, however, there is a single-strand of RNA.

Antivirals- Drugs that are used to prevent or cure a disease caused by a virus, by interfering with the ability of the virus to multiply in number or spread from cell to cell.

Asian Flu/Influenza- Common name for the influenza A strain that killed over a million people around the world in the 1957 pandemic.

Auxiliary Virus- AAV is incapable of carrying out a replication cycle in the course of cell infection. The presence of another virus, called a helper (auxiliary), provides additional functions needed for viral replication and leads to a productive infectious cycle. This dependency is the origin of the genus name of AAVs (dependovirus).

Avian Influenza- Avian influenza, or "bird flu", is a contagious disease of animals caused by viruses that normally infect only birds and, less commonly, pigs. Avian influenza viruses are highly species-specific, but have, on rare occasions, crossed the species barrier to infect humans.