Refers to vaccines which incorporate live, but sufficiently weakened infectious agents so that they can infect enough to activate the body's immune system to fight the virus without allowing the virus to continue to multiply to the point where it causes illness.

An agent which, while not having any specific antigenic effect in itself, may stimulate the immune system, increasing the response to a vaccine.

A substance produced by bacteria or fungi that destroys or prevents the growth of other bacteria and fungi. Antibiotics are not effective against viruses.

A protein produced by the body's immune system in response to a foreign substance (antigen). An antibody reacts specifically with the antigen that induced its formation and inactivates the antigen. Our bodies fight off an infection by producing antibodies.

Any foreign substance, usually a protein, that stimulates the body's immune system to produce antibodies (antibody generation).

Drug used to prevent or cure a disease caused by a virus; antivirals interfere with the ability of viruses to multiply in number or spread from cell to cell.

An infection caused by avian influenza (or bird flu) viruses that are found naturally among birds. Wild birds worldwide commonly carry the viruses in their intestines or respiratory tracts but usually do not get sick from them. However, avian influenza can be contagious among birds and can make some domesticated birds - including chickens, ducks and turkeys - very sick and kill them. The risk to humans of avian influenza is generally low to because the viruses occur mainly among birds and do not easily infect humans. However, during an outbreak of avian influenza among poultry there is a possible risk to people who have contact with infected birds or surfaces that have been contaminated with excretions from infected birds that carry the virus.

See avian influenza.

All the cumulative measures that can or should be taken to keep disease (viruses, bacteria, fungi, protozoa, parasites) from a farm and to prevent the transmission of disease (by humans, insects, rodents and wild birds/animals) within an infected farm to neighbouring farms.

Birds kept for the purpose of producing hatching eggs

Chicken raised for meat production.

Is an animal/person who is infected with an agent that causes a disease who shows no sign of illness. Asymptomatic carriers shed the causative agent, such as a virus or bacteria, and so can pass the disease on to others.

Means an individual animal infected by a pathogenic agent with or without clinical signs.

Long-lasting and recurrent or characterized by long suffering.

A contagious disease is easily spread from one animal to another by contact with the infectious agent that causes the disease. The agent may be in droplets of aerosols made by coughing or sneezing, contaminated food utensils, water or food.

Killing poultry that belong to a flock in which avian influenza has been identified to avoid spread of the disease.

All birds aged not more than 72 hours after hatching.

A new infection resulting from the evolution or change of an existing pathogenic agent, a known infection spreading to a new geographic area or population, or a previously unrecognized pathogenic agent or disease diagnosed for the first time and which has a significant impact on animal or public health.

A protein that acts as a catalyst. Every chemical reaction in living organisms is facilitated by an enzyme.

The occurrence of cases of disease in excess of what is usually expected for a given period of time.

A group of animals with a defined epidemiological relationship that share approximately the same likelihood of exposure to a pathogen. This may be because they share a common environment (e.g. animals in a pen), or because of common management practices. Usually, this is a herd or a flock. However, an epidemiological unit may also refer to groups such as animals belonging to residents of a village, or animals sharing a communal animal handling facitity. The epidemiological relationship may differ from disease to disease, or even strain to strain of the pathogen..

The study of diseases or conditions in animal or human populations and the factors that influence their incidence and prevalence.

The premises in which animals are kept.

A large-scale industrial site where many animals (generally chickens, turkeys, cattle, or pigs) are confined and treated with hormones and antibiotics to maximize growth and prevent disease.

excrement; droppings (of birds).

Any group of birds continuously housed in one building or part of a building separated from other parts of that building by a solid partition and having its own ventilation system, or, in the case of free range birds, any group of birds having common access to one or more buildings or houses. More than one flock of birds may exist in one establishment.

Refers to animals (usually poultry) that are not confined and can thus range freely for food rather than being confined in an enclosure.

The basic unit of inheritance. A gene is a segment of DNA that specifies the structure of a protein or an RNA molecule.

relating to, or influenced by, the origin or development of something.

A protein antigen which forms a rod-shaped spike on the surface of an influenza virus. The name haemagglutinin is given because the spikes are capable of adhering to red blood cells, causing them to be agglutinated (clumped).

It is an infection of poultry caused by any influenza A virus of the H5 or H7 Subtypes with an IVPI in 6-week-old chickens greater than 1.2 or, as an alternative, cause at least 75% mortality in 4-to 8-week-old chickens infected intravenously. H5 and H7 viruses which do not have an IVPI of greater than 1.2 or cause less than 75% mortality in an intravenous lethality test should be sequenced to determine whether multiple basic amino acids are present at the cleavage site of the haemagglutinin molecule (HA0); if the amino acid motif is similar to that observed for other HPAI isolates, the isolate being tested should be considered as HPAI.

An organism on or in which other organism lives.

One of 16 different known subtypes of avian flu (bird flu) viruses. Some H5N1 viruses are highly pathogenic, meaning they can cause severe disease and death in birds. H5N1 viruses have been found in birds around the world. As the spread of H5N1 infection among birds increases, so, too, does the opportunity for H5N1 to be transmitted directly from birds to humans. Currently, the H5N1 virus has not resulted in human to human spread.

The longest period which elapses between the introduction of the pathogen into the animal and the occurrence of the first clinical signs of the disease.

Is the presence of the pathogenic agent in the host.

The longest period during which an affected animal can be a source of infection.

Animal/person who is immune to a particular infection (n.); relating to or conferring immunity (to disease or infection) (adj.).

The cells, tissues and organs that assist the body to resist infection and disease by producing anitbodies and/or altered cells that inhibit the multiplication of the infectious agent.

The condition in which an organism can resist disease.

Unable to develop a normal immune response usually because of malnutrition or immunodeficiency or immunosuppressive therapy

Refers to vaccines which incorporate dead infectious agents and teach the body's immune system to detect and destroy viruses identical to or very closely related to the ones they contain.

A contagious illness characterized by fever, headaches, sore throat, body aches and congestion of the nose.

A highly contagious, febrile, acute respiratory infection of the nose, throat, bronchial tubes and lungs. It is caused by a category of the influenza virus that is characterized by specific internal proteins and further sub-grouped according to variations in two surface proteins (hemagglutinin and neuraminidase). It can be responsible for severe and potentially fatal clinical illness of both animals and humans. Influenza type A caused the pandemic influenza infections of the 20th century.

A category of influenza virus characterized by specific internal proteins that infects only humans, causes less severe clinical illness than type A, and spreads in regional rather than pandemic outbreaks.

A category of influenza virus characterized by specific internal proteins that does not cause significant clinical illness.

A pure specimen obtained by culture.

See inactivate vaccine.

Any procedure which causes the death of an animal

Bird raised to lay eggs.

See activated vaccine.

Is defined as an infection of poultry caused by any influenza virus that are not HPAI viruses.

The continuous investigation of a given population or subpopulation, and its environment, to detect changes in the prevalence of a disease or characteristics of a pathogenic agent.

A permanent change in the genetic material of a cell that may be normal and harmless or could cause disease or change diseases in a way that make them more harmful. 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

An enzyme which forms a spike-shaped projection on the surface of an influenza virus particle, dissolving the protective cellular mucous lining and allowing release of newly-formed virus particles from the surface of the infected cell.

A new class of antiviral agent that selectively inhibits neuraminidase activity in both influenza type A and type B viruses, while having no effect on human neuraminidase.

A large molecule made up of a sequence of phosphorylated nitrogen-containing bases. DNA and RNA are both nucleic acids.

Also known as the N95 respirator, the N95 mask is a lightweight, nose-and-mouth respirator that can provide some level of protection for the wearer from viruses, including avian flu. The N95 designation is an efficiency rating that means the mask blocks about 95 percent of particles that are 0.3 microns in size or larger. The Centers For Disease Control and Prevention (CDC) has recommended the use of N95 masks for protection against the avian flu virus.

see World Organisation for Animal Health.

The confirmed presence of disease or infection of one or more cases in a defined epidemiological unit (e.g flock, herd, farm or village) and during a specified period of time.

An epidemic that is geographically widespread; occurring throughout a region or even throughout the world.

Occurs when a new strain of influenza virus emerges, spreading around the world and infecting many people at once. An influenza virus capable of causing a pandemic is one against which people have no natural immunity, can easily spread from person to person, and is capable of causing severe disease.

Any micro-organism or material that can cause disease.

able to cause disease; "infective agents"; "pathogenic bacteria".

Stands for Polymerase Chain Reaction, a highly sensitive test that can detect DNA fragments of viruses or other organisms in blood or tissue. It works by repeatedly copying genetic material using heat cycling and enzymes similar to those used by cells.

See PCR.

All domesticated birds used for the production of meat or eggs for consumption, for the production of other commercial products, for restocking, supplies of game, or for breeding these categories of birds.

The total number of cases or outbreaks of a disease that is present in a population at risk, in a particular geographical area, at one specified time or during a given period.

A medical procedure or practice that prevents or protects against a disease or condition (eg, vaccines, antibiotics, drugs).

prevention of disease

A large molecule composed of a linear sequence of amino acids. This linear sequence is a protein's primary structure. Short sequences within the protein molecule can interact to form regular folds (eg, alpha helix and beta pleated sheet) called the secondary structure.

Any substance used in a chemical reaction to bring about the chemical change.

Occurs when the genes from two different and distinct virus strains rearrange and recombine to produce a new, genetically different strain. In the case of bird flu, the fear is that a person could be infected with two viruses at the same time (co-infected) - a virulent bird flu virus and a common human flu virus - resulting in the exchange of genetic information between the two. The exchange of genetic material could result in a deadly virus that is as easily transmissible from one person to another as the common seasonal flu viruses strains.

In the context of avian influenza, rehabilitation refers to the process of restoring a poultry production system after an outbreak has damaged it, whether through the deaths of poultry due to disease or through culling to prevent spread of the disease.

In the context of avian influenza, restocking refers to the process of introducing new birds to replace those lost through death caused by the disease or through culling to prevent spread of the disease.

The likelihood of the occurrence and the likely magnitude of the consequences of an adverse event to animal or human health in the importing country during a specified time period, as a result of a hazard.

Is a blood test to detect the presence of antibodies in the blood serum. Such antibodies may be formed against a microorganism. Serological tests may be performed for diagnostic purposes when an infection is suspected.

Any procedure which causes the death of an animal by bleeding.

Is the regular collection, monitoring and analysis of information in a given population or subpopulation to detect the presence of a pathogenic agent or disease; the frequency and type of surveillance will be determined by the epidemiology of the pathogenic agent or disease, and the desired outputs.

A substance produced from an infectious organism that stimulates an immune response (but not disease) thereby protecting against subsequent infection by that organism.

The successful immunisation of susceptible animals through the administration of a vaccine comprising antigens appropriate to the disease to be controlled

The study of viruses and viral disease.

Highly lethal; causing severe illness or death.

Type of microscopic parasite that infects cells in biological organisms but is unable to reproduce outside a living host cell; viruses may subvert the normal functions of a host cell, causing it to behave in a manner determined by the virus.

An area of land in which, at least some of the time, water saturates the soil, and which often provides a natural environment where wild (migratory) birds collect and breed.

intergovernmental organisation set up in 1924 to ensure transparency in the issue of global animal disease and zoonosis, provide expertise and encourage international solidarity in the control of animal diseases, safeguard world trade by publishing health standards for international trade in animals and animal products, provide a better guarantee of the safety of food of animal origin, and promote animal welfare through a science-based approach

any disease or infection which is naturally transmissible from animals to humans.