A, B, C

AI (Avian Flu) —: Influenza viruses that occur naturally among wild birds. Low pathogenic AI is common in birds and causes few problems. Highly pathogenic H5N1 is deadly to domestic fowl, can be transmitted from birds to humans, and is deadly to humans. There is virtually no human immunity and human vaccine availability is very limited.
Antibiotic —: A substance produced by bacteria or fungi that destroys or prevents the growth of other bacteria and fungi.
Antibodies —: Proteins produced by an organism’s immune system to recognize foreign substances.
Antigenic Drift —: One of two ways that influenza viruses can change (the other is antigenic shift, see below). Antigenic drift refers to small, gradual changes that occur through point mutations in the two genes that contain the genetic material to produce the main surface proteins, hemagglutinin, and neuraminidase. These point mutations occur unpredictably and result in minor changes to these surface proteins. Antigenic drift produces new virus strains that may not be recognized by antibodies to earlier influenza strains. This process works as follows: a person infected with a particular influenza virus strain develops antibody against that strain. As newer virus strains appear, the antibodies against the older strains might not recognize the “newer” virus, and infection with a new strain can occur. This is one of the main reasons why people can become infected with influenza viruses more than one time and why global surveillance is critical in order to monitor the evolution of human influenza virus strains for selection of which strains should be included in the annual production of influenza vaccine. In most years, one or two of the three virus strains in the influenza vaccine are updated to keep up with the changes in the circulating influenza viruses. For this reason, people who want to be immunized against influenza need to be vaccinated every year.
Antigenic Shift —: A sudden, major change in the antigenic structure of a virus, usually the result of a genetic mutation. Antigenic shift is one of two ways that influenza viruses can change (the other is antigenic drift, see above). Antigenic shift refers to an abrupt, major change to produce a novel influenza A virus subtype in humans that was not currently circulating among people. Antigenic shift can occur either through direct animal (poultry)-to-human transmission or through mixing of human influenza A and animal influenza A virus genes to create a new human influenza A subtype virus through a process called genetic reassortment. Antigenic shift results in a new human influenza A subtype.
Antigens —: Any substance that stimulates an immune response by the body. The immune system recognizes such substances as being foreign, and produces cellular antibodies to fight them. Antigen/antibody response is an important part of a person’s immunity to disease.
Antiviral —: Drug that is 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 —: A pandemic of influenza A (H2N2) in 1957-58. First identified in China in late February 1957, the Asian flu spread to the United States by June 1957 where it caused about 70,000 deaths. Also known as Asian influenza.
Avian Influenza (Avian Flu, Bird Flu) —: Influenza viruses that occur naturally among wild birds. Low pathogenic AI is common in birds and causes few problems. Highly pathogenic H5N1 is deadly to domestic fowl, can be transmitted from birds to humans, and is deadly to humans. There is virtually no human immunity and human vaccine availability is very limited. In 1997 (A/H5N1) and 1999 (A/H9N2) two new influenza pandemic threats emerged in Hong Kong. Both of these avian viruses have infected humans directly without having been altered first by infecting pigs as an intermediate host. These viruses are currently found in birds. In 1999, two children were infected and became ill with A/H9N1. After initially killing 18 people in Hong Kong in 1997 (www.PandemicFlu.gov), the A/H5N1 virus has gone on to infect at least 387 people (confirmed by WHO) in 15 countries killing 245 (confirmed by WHO) as of September 10, 2008. The highest number of deaths has occurred in Indonesia where 82% of those who are infected have died. Much of the current pandemic preparedness efforts in Idaho, the United States, and elsewhere in the world have been predicated on the potential of A/H5N1 becoming the next pandemic influenza. Human-to-human transmission of the virus has occurred, but only in a few instances on a very limited basis between family members and close contacts. Confirmed (by the OIE) outbreaks of highly pathogenic H5N1 (HPAI) in birds have been reported in 26 countries in 2008. Unless the virus becomes easily transmissible between humans through mutations or genetic drift, A/H5N1 will not become a pandemic. To learn more about A/H5N1, see an updated map of the countries with cases of H5N1 in humans confirmed by the World Health Organization (WHO), and see the H5N1 timeline visit PandemicFlu.gov. For additional information about H5N1 and other viruses in animals please visit the OIE (Organisation for Animal Health) Website.
Bacteria —: Single-celled microorganisms, some of which can cause disease
Bird Flu (Avian Flu) —: Influenza viruses that occur naturally among wild birds. Low pathogenic AI is common in birds and causes few problems. Highly pathogenic H5N1 is deadly to domestic fowl, can be transmitted from birds to humans, and is deadly to humans. There is virtually no human immunity and human vaccine availability is very limited.
Carrier —: A person or animal that harbors a specific infectious agent without visible symptoms of the disease. A carrier acts as a potential source of infection.
CDC —: Centers for Disease Control and Prevention, the U.S. government agency at the forefront of public health efforts to prevent and control infectious and chronic diseases, injuries, workplace hazards, disabilities, and environmental health threats. CDC is one of 13 major operating components of the Department of Health and Human Services.

D, E, F, G, H

Disease —: Formally speaking, a disease is the condition in which the functioning of the body or a part of the body is interfered with or damaged. In a person with an infectious disease, the infectious agent that has entered the body causes it to function abnormally in some way or ways. The type of abnormal functioning that occurs is the disease. Usually the body will show some signs and symptoms of the problems it is having with functioning. Disease should not be confused with infection.
Epidemic —: A disease occurring suddenly in humans in a community, region or country in numbers clearly in excess of normal.
Epizootic —: A disease occurring suddenly in animals in a community, region or country in numbers clearly in excess of normal.
FAO —: Food and Agriculture Organization of the United Nations leads international efforts to defeat hunger. FAO serves both developed and developing countries and acts as a neutral forum where all nations meet as equals to negotiate agreements and debate policy.
Flu (Influenza) —: A serious disease caused by viruses that infect the respiratory tract.
Genetic Drift (Antigenic Drift) —: One of two ways that influenza viruses can change (the other is antigenic shift, see below). Antigenic drift refers to small, gradual changes that occur through point mutations in the two genes that contain the genetic material to produce the main surface proteins, hemagglutinin, and neuraminidase. These point mutations occur unpredictably and result in minor changes to these surface proteins. Antigenic drift produces new virus strains that may not be recognized by antibodies to earlier influenza strains. This process works as follows: a person infected with a particular influenza virus strain develops antibody against that strain. As newer virus strains appear, the antibodies against the older strains might not recognize the “newer” virus, and infection with a new strain can occur. This is one of the main reasons why people can become infected with influenza viruses more than one time and why global surveillance is critical in order to monitor the evolution of human influenza virus strains for selection of which strains should be included in the annual production of influenza vaccine. In most years, one or two of the three virus strains in the influenza vaccine are updated to keep up with the changes in the circulating influenza viruses. For this reason, people who want to be immunized against influenza need to be vaccinated every year.
Great Pandemic (Spanish Influenza) —: A severe influenza pandemic that occurred worldwide in 1918 — 1919. Recent research estimates global mortality from the 1918-1919 pandemic at anywhere between 30 and 50 million. An estimated 675,000 Americans were among the dead.
Hemagglutinin (HA) —: One of two proteins on the surface of the influenza A virus used to name influenza A subtypes (e.g., H5N1). See also, neuraminidase (NA).
Hong Kong Flu —: Influenza caused by a serotype of influenza virus type A; it was first identified in Hong Kong during the 1968 epidemic.
Host —: An organism on or in which a parasite lives.
HPAI —: Highly Pathogenic form of Avian Influenza. Avian flu viruses are classified based upon the severity of the illness and HPAI is extremely infectious among humans. The rapid spread of HPAI, with outbreaks occurring at the same time, is of growing concern for human health as well as for animal health.

I, J, K, L

Immunity —

Ability to resist attack or overcome infection by invading microbes or larger parasites. Immunity is based on the proper functioning of the body's immune system.

Immunization —

The process of inducing immunity, usually through inoculation or vaccination.

Infection —

Invasion of the body or a body part by a pathogenic organism, which multiplies and produces harmful effects on the body’s tissues.

Influenza —

A serious disease caused by viruses that infect the respiratory tract. There are three types of influenza viruses: A, B, and C. Only influenza A viruses are further classified by subtype on the basis of the two main surface glycoproteins hemagglutinin (HA) and neuraminidase (NA). Influenza A subtypes and B viruses are further classified by strains. Humans can be infected with influenza types A, B, and C viruses. Subtypes of influenza A that are currently circulating among people worldwide include H1N1, H1N2, and H3N2 viruses. Wild birds are the natural host for all known subtypes of influenza A viruses. Typically, wild birds do not become sick when they are infected with avian influenza A viruses. However, domestic poultry, such as turkeys and chickens, can become very sick and die from avian influenza, and some avian influenza A viruses also can cause serious disease and death in wild birds.

Influenza A (and its subtypes) —

Influenza type A viruses can infect people, birds, pigs, horses, and other animals, but wild birds are the natural hosts for these viruses. Influenza type A viruses are divided into subtypes and named on the basis of two proteins on the surface of the virus: hemagglutinin (HA) and neuraminidase (NA). For example, an “H7N2” virus designates an influenza A subtype that has an HA 7 protein and an NA 2 protein. Similarly an “H5N1” virus has an HA 5 protein and an NA 1 protein. There are 16 known HA subtypes and 9 known NA subtypes. Many different combinations of HA and NA proteins are possible. Only some influenza A subtypes (i.e., H1N1, H1N2, and H3N2) are currently in general circulation among people. Other subtypes are found most commonly in other animal species. For example, H7N7 and H3N8 viruses cause illness in horses, and H3N8 also has recently been shown to cause illness in dogs. Only influenza A viruses infect birds, and all known subtypes of influenza A viruses can infect birds. However, there are substantial genetic differences between the influenza A subtypes that typically infect birds and those that infect both people and birds. Three prominent subtypes of the avian influenza A viruses that are known to infect both birds and people are:

Influenza A H5 — Nine potential subtypes of H5 are known. H5 infections, such as HPAI (highly pathogenic avian influenza) H5N1 viruses currently circulating n Asia and Europe, have been documented among humans and sometimes cause severe illness or death.
Influenza A H7 — Nine potential subtypes of H7 are known. H7 infection in humans is rare but can occur among persons who have direct contact with infected birds. Symptoms may include conjunctivitis and/or upper respiratory symptoms. H7 viruses have been associated with both LPAI (low pathogenic avian influenza, e.g., H7N2, H7N7) and HPAI (high pathogenic avian influenza, e.g., H7N3, H7N7), and have caused mild to severe and fatal illness in humans.
Influenza A H9 — Nine potential subtypes of H9 are known; influenza A H9 has rarely been reported to infect humans. However, this subtype has been documented only in a low pathogenic form.

Influenza Type B —

Influenza B viruses are usually found only in humans. Unlike influenza A viruses, these viruses are not classified according to subtype. Influenza B viruses can cause morbidity and mortality among humans, but in general are associated with less severe epidemics than influenza A viruses. Although influenza type B viruses can cause human epidemics, they have not caused pandemics.

Influenza Type C —

Influenza type C viruses cause mild illness in humans and do not cause epidemics or pandemics. These viruses are not classified according to subtype.

Influenza Strains —

Influenza B viruses and subtypes of influenza A virus are further characterized into strains. There are many different strains of influenza B viruses and of influenza A subtypes. New strains of influenza viruses appear and replace older strains. This process occurs through antigenic drift. When a new stain of human influenza virus emerges, antibody protection that may have developed after infection or vaccination with an older strain may not provide protection against the new strain. Therefore, the influenza vaccine is updated on a yearly basis to keep up with the changes in influenza viruses.

Intermediate Host —

A host in which a parasite goes through its larval or developmental stages.

Isolation —

A state of separation between persons or groups to prevent the spread of disease. The first published recommendations for isolation precautions in United States hospitals appeared as early as 1877, when a handbook recommended placing patients with infectious diseases in separate facilities. Isolation measures can be undertaken in hospitals or homes, as well as in alternative facilities.

Isolation (Idaho’s Definition) —

as defined in Idaho Code §56-1001(4) "Isolation" means the separation of infected persons, or of persons suspected to be infected, from other persons to such places, under such conditions, and for such time as will prevent transmission of the infectious agent.

LPAI (Low Pathogenic form of Avian Influenza) —

Most avian flu strains are classified as LPAI and typically cause little or no clinical signs in infected birds. However, some LPAI virus strains are capable of mutating under field conditions into HPAI viruses.

M, N, O, P

Morbidity —

State of being diseased; morbidity rate is the incidence or prevalence of disease in a specific population.

Mortality —

Death; mortality rate is a measure of the number of deaths in a population during a specified interval of time.

Mutation —

Any alteration in a gene from its natural state. This change may be disease causing or a benign, normal variant. Specific mutations and evolution in influenza viruses cannot be predicted, making it difficult if not impossible to know if or when a virus such as H5N1 might acquire the properties needed to spread easily among humans.

Neuraminidase (NA) —

One of two proteins on the surface of the influenza A virus used to name influenza A subtypes (e.g., H5N1). See also, hemagglutinin (HA).

OIE (World Organisation for Animal Health) —

an international organization including 167 member countries that collects, analyses, and reports information on global animal disease situations.

Outbreak —

sudden appearance of a disease in a specific geographic area (e.g., neighborhood or community) or population (e.g., adolescents)

Pandemic —

The worldwide outbreak of a disease in humans in numbers clearly in excess of normal. A global influenza pandemic may occur if three conditions are met:

A new subtype of influenza A virus is introduced into the human population.
The virus causes serious illness in humans.
The virus can spread easily from person to person in a sustained manner.

Pandemic Flu —

Virulent human flu that causes a global outbreak, or pandemic, of serious illness. Because there is little natural immunity, the disease can spread easily from person to person.

Pathogenic —

Causing disease or capable of doing so.

Pneumonia —

Inflammation of the lungs, often caused by infection with viruses or bacteria

Public Health Service —

A federal agency comprised of 12 core public health offices and the Commissioned Corps, a uniformed service of more than 6,000 health professionals who serve at Health and Human Services (HHS) and other federal agencies.

Q, R, S, T, U

Quarantine —: The period of isolation decreed to control the spread of disease. Before the era of antibiotics, quarantine was one of the few available means of halting the spread of infectious disease. It is still employed today as needed. The list of quarantinable diseases in the U.S. is established by Executive Order of the President, on recommendation of the Secretary of the Department of Health and Human Services, and includes cholera, diphtheria, infectious tuberculosis, plague, smallpox, yellow fever, and viral hemorrhagic fevers (such as Marburg, Ebola, and Congo-Crimean disease). In 2003, SARS (severe acute respiratory syndrome) was added as a quarantinable disease. In 2005 another disease was added to the list, influenza caused by novel or reemergent influenza viruses that are causing, or have the potential to cause, a pandemic.
Quarantine (Idaho’s Definition) —: as defined in Idaho Code §56-1001 (8) “Quarantine” means the restriction placed on the entrance to and exit from the place or premises where an infectious agent or hazardous material exists.
Russian Flu —: A widespread epidemic of mild influenza caused by an H1N1 virus similar to the virus that circulated worldwide during the early 1950s that occurred from November 1977 through mid-January 1978 in people less than 25 years old in the Union of Soviet Socialist Republics. Outbreaks of Russian flu occurred in school populations and military recruits in the United States starting in mid-January. Many other countries reported outbreaks of H1N1 virus in the winter of 1978.
Seasonal Flu (“Common Flu”, “Winter Flu”) —: A respiratory illness that can be transmitted person to person. Most people have some immunity, and a vaccine is available.
Spanish Influenza —: Influenza that caused several waves of pandemic in 1918 — 1919, resulting in 20-50 million deaths worldwide. (See the Great Pandemic)
Swine Flu —: A respiratory disease of pigs caused by type A influenza that regularly causes outbreaks of influenza among pigs. Swine flu viruses cause high levels of illness and low death rates among pigs. Swine influenza viruses may circulate in swine throughout the year, but most outbreaks among swine herds occur during the late fall and winter months similar to humans.
U.S. Department of Health and Human Services —: A department of the federal executive branch responsible for protecting the health of all Americans and providing essential human services, especially for those who are least able to help themselves. The department includes more than 300 programs and is responsible for the Social Security Administration, the Public Health Service, and other programs designed to promote public welfare.

V, W, X, Y, Z

Vaccine —: Preparation containing either killed or weakened live microorganisms or their toxins, introduced by mouth, by injection, or by nasal spray to stimulate production of antibodies against an infectious agent.
Vaccination —: Producing immunity against pathogens, such as viruses and bacteria, by the introduction of live, killed, or altered antigens that stimulate the body to produce antibodies against more dangerous forms.
Virulent —: Highly lethal; causing severe illness or death.
Virus —: Any of various simple submicroscopic parasites of plants, animals, and bacteria that often cause disease and that consist essentially of a core of RNA or DNA surrounded by a protein coat. Unable to replicate without a host cell, viruses are typically not considered living organisms.
WHO —: World Health Organization, an agency of the United Nations established in 1948 to further international cooperation in improving health conditions.
World War I —: A war between the allies (Russia, France, British Empire, Italy, United States, Japan, Rumania, Serbia, Belgium, Greece, Portugal, Montenegro) and the Central Powers (Germany, Austria-Hungary, Turkey, Bulgaria) from 1914 to 1918.
Zoonoses —: Diseases that are transferable from animals to humans.

All definitions are found at one or more of the following sources:

Columbia Electronic Encyclopedia. Retrieved September 16, 2008 from Columbia Electronic Encyclopedia by Columbia University Press.

Encyclopedia Britannica. Retrieved September 16, 2008 from Encyclopedia Britannica Online www.britannica.com/

Flu Terms Defined. Retrieved September 16, 2008, from PandemicFlu.gov Web site: www.pandemicflu.gov/popup.html

Glossary. Retrieved September 16, 2008, from Centers for Disease Control and Prevention Web site: www.cdc.gov

Glossary. Retrieved September 16, 2008, from PandemicFlu.gov Web site: www.pandemicflu.gov/glossary/index.html

Gregg, M. B. , Hinmand, A. R, & Craven, R. B (1978). The Russian flu. Its history and implications for this year. The Journal of the American Medical Association. 240(21), 2260 - 2263.

HHS: What We Do. Retrieved September 22, 2008, from U.S. Department of Health & Human Services Web site: www.hhs.gov/about/whatwedo.html/

Influenza Viruses. Retrieved September 22, 2008, from Centers for Disease Control and Prevention Web site: www.cdc.gov/flu/avian/gen-info/flu-viruses.htm

Questions & Answers. Retrieved September 16, 2008, from Centers for Disease Control and Prevention Web site: www.cdc.gov

The Great Pandemic. Retrieved September 16, 2008, from PandemicFlu.gov Web site: 1918.pandemicflu.gov/

The New Dictionary of Cultural Literacy, Third Edition. Edited by E.D. Hirsch, Jr., Joseph F. Kett, and James Trefil. Published by Houghton Mifflin Company. Web site: www.bartleby.com/

WordNet. Retrieved September 16, 2008, from Princeton University Web site: wordnet.princeton.edu/

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