Avian influenza is a disease caused by a virus, which has multiple strains or types, some of which are more dangerous than others. Influenza is divided into three types: A, B and C. Type A influenza includes most human and all avian influenza viruses.
Avian influenza viruses can be divided into highly pathogenic (HPAI) and low pathogenic (LPAI) strains based on its ability to cause disease in poultry.
Influenza viruses are divided into subtypes based on the two proteins, haemaglutinin (H) and neuraminidase (N), that they have on their surfaces. There are 16 recognized H types, and 9 N types, and these are known to occur in a number of different combinations - the combination that is the cause for current concern is H5N1. Only two types of avian influenza viruses, H5 and H7, are known to include highly pathogenic viruses. Not all H5 and H7 influenza viruses are highly pathogenic, but H5N1 is. This form may cause disease in chickens and some other species of birds that affects multiple internal organs and has a mortality rate that can reach 90-100 percent, often within 48 hours.

The H5N1 virus is the strain of avian influenza that has infected numerous species of birds in Asia, Europe and Africa since the end of 2003. It has not been found in birds in North or South America, including the Caribbean.

No. Influenza, commonly called 'the flu', is a contagious respiratory disease in humans which causes fever, headaches, sore throat, body aches and congestion of the nose; it occurs every year, usually in winter. It causes illness in 5 out of 100 adults and 20 out of 100 children each year; it kills between 250,000 and 500,000 people around the world every year, mostly among the elderly and the very young.

Avian influenza, commonly called 'bird flu', is the general name for a form of viral disease that affects birds, particularly poultry, and can take two forms: highly pathogenic avian influenza (HPAI) and low pathogenic avian influenza (LPAI).

Much of the scientific evidence suggests that domestic poultry provide a favourable environment for the entry, spread and shift to high virulence of influenza viruses, which were mostly mild and confined to waterfowl in the past. The dramatic growth in domestic poultry production is part of the explanation.
The origin of the current outbreak of avian influenza can be traced to East/Southeast Asia, home to an estimated six billion domestic birds. More than half of the domestic bird population is in medium- to large-scale intensive poultry holdings where fairly strict hygiene, prevention and containment (biosecurity) measures are in place; however, a sizeable part of the poultry population remains with the smallholder sector run by an estimated 200 million farmers, each keeping 5-15 birds, mainly ducks, chicken, geese, turkeys and quail. Backyard or village poultry is characterised by scavenging birds and open coops, and is exposed to viruses carried by wild birds. Seasonal seeding of influenza viruses into backyard poultry systems by migrating waterfowl allows regular addition of new viruses to the diverse domestic poultry virus pool and may explain some of the geospatial features of regional virus distribution.

However, the rapid spread of certain virus types suggests dissemination mechanisms within the poultry sub-sector itself, such as live poultry movements or transports involving infected materials such as unclean cages or dirty egg crates. The risks from live bird or 'wet' markets appear the most obvious and have in the past been incriminated as a critical risk.

Avian influenza is most often spread by contact between infected birds and healthy birds. It may also be spread indirectly through contact with contaminated equipment and materials. The avian influenza virus is found in secretions from the nares (nostrils), mouth, and eyes of infected birds and is also excreted in their droppings. Contact with contaminated droppings is the most common means of bird-to-bird transmission, although airborne secretions are another important means of transmission, especially within poultry houses. Wild duck droppings can introduce low pathogenic (LPAI) into domestic flocks raised on range or in open flight pens.
How highly pathogenic avian influenza (HPAI) is initially introduced into poultry flocks remains unclear. However, the spread of avian influenza between poultry facilities almost always results from the movement of infected birds or contaminated people and equipment (including clothing, boots, and vehicles). Avian influenza virus can also be found on the outer surfaces of eggshells (but rarely inside); therefore, egg transfer is a potential means of avian influenza transmission. Airborne transmission of avian influenza virus from farm to farm is not likely.

H5N1 HPAI can be spread from birds to people as a result of direct contact with infected birds, such as during home slaughter and plucking of infected poultry. Public health concerns centre around the potential for the virus to mutate or combine with other influenza viruses to a form that could easily spread from person to person. If that happens, there is a risk that the virus could rapidly spread worldwide and cause large numbers of humans to become ill or die (a pandemic).

Most outbreaks of avian influenza can be linked to movements of poultry, poultry manure, poultry by-products and accidental transfer of infected material such as bird droppings, bedding straw or soil on vehicles, equipment, cages or egg flats, clothes and shoes. Worldwide, unregulated movement of poultry is the most important way that the disease is spread.
Live animal or 'wet' markets may have played a major part in sustaining the virus in Southeast Asia, They were identified as the source of the H5N1 infection in chicken farms in Hong Kong in 1997 when approximately 20 percent of the chickens in live poultry markets were found to be infected. The same situation occurred in Viet Nam, where the circulation of H5N1 in geese in live bird markets in Hanoi had been documented three years before the 2004 outbreaks on chicken farms.

There is also a huge international trade in poultry - both legal and illegal. The legal trade involves millions of hatching eggs and poultry being shipped to destinations worldwide; information on the extent of the unregulated and illegal poultry trade is scarce but interceptions in recent years indicate lapses in border controls despite the risk. The widespread illegal trade in ornamental, sporting and caged birds has also transported H5N1-infected birds over large distances. One of the most likely sources of infection in captive birds in Asia is again in 'wet' markets, where domestic and wild-caught birds are kept in close proximity, posing a risk of cross-contamination.

It depends on the amount of virus contained in the droppings, temperature and moisture content. Generally speaking however, the virus dies more quickly in higher temperatures and the drier the droppings are.

Yes, the possibility of HPAI H5N1 breaking out always exists but the likelihood of it happening varies from country to country. This largely depends on the level of biosecurity in place on farms and in commercial poultry production facilities, on the safeguards in place to monitor disease in poultry flocks, and on the level of compliance with import and export controls.

Everyone, including pet owners, should be aware of the potential of the H5N1 avian influenza virus to cause disease and death, as well as how it can be transmitted. If H5N1 HPAI is identified in your country, the competent authorities will issue instructions on the precautions to take, but there is no reason to abandon cats, dogs, or other pets because of concerns about contracting or spreading the virus.

Although H5N1 can cause serious disease in people, the virus is "hard to catch". Transmission from birds to human remains difficult, usually involving prolonged and close contact, and so far the virus has not been shown to spread from person to person.
In the last 100 years there have been at least three major pandemics of human influenza A, which killed many people around the world. The origins of these deadly virus strains remain uncertain, but at least two are thought to have arisen when avian influenza and human influenza viruses came together, possibly in pigs, and reassorted their genetic material. Continued outbreaks of H5N1 increase the chances of this happening again, especially as the current strain of H5N1 is exceptional in that it can (though rarely does) pass directly from poultry to humans.
Almost always, human infections have occurred in people who have been closely associated with poultry. Given the substantial number and distribution of outbreaks in domestic poultry and waterfowl, there have been relatively few cases in people (WHO statistics up to 29 November 2006 indicate 258 confirmed infections, with 154 fatalities), indicating that the transmission of the virus from poultry to people remains inefficient.

For the latest WHO statistics on people affected, please follow this link.

We do not know for certain, but direct contact with infected poultry, or surfaces and objects contaminated by their droppings is presently considered the main route for infection of humans by the avian H5N1 virus. To date, most human cases have occurred in rural or urban fringe areas where many households keep small poultry flocks, which often roam freely, sometimes entering homes or sharing outdoor areas where children play. As infected birds shed large quantities of virus in their droppings, opportunities for exposure to infected droppings or to environments contaminated by the virus are abundant under such conditions. Moreover, because many households depend on poultry for income and food, families sometimes sell or slaughter and consume birds when signs of illness appear in a flock, rather than disposing of the birds safely, and this practice has proved difficult to change. Exposure is considered most likely during slaughter, plucking and butchering. There is no evidence that properly cooked poultry or eggs can be a source of infection.

Yes, but even though the H5N1 virus may have the potential to change into a virus that can easily pass from person to person, there is no evidence that this has happened. An influenza pandemic is a rare event and has occurred only three times over the last 100 years (in 1918 with around 50 million deaths, in 1957 with almost two million deaths, and in 1968 with about one million deaths).

It is impossible to calculate the risk of a human pandemic. The H5N1 avian influenza virus meets two out of three conditions necessary to cause a human pandemic. It can infect humans and it causes serious illness, but critically it does not spread easily and sustainably between humans. If this virus subtype changes to spread easily and sustainably between humans it may have the capacity to cause a pandemic, but we cannot predict if, when or where this will happen. Nor can we predict whether the virus would retain its ability to cause serious disease. But we can take precautions to protect humans and we can take action where avian influenza is identified in poultry.

The specific actions to be taken with regard to controlling marketing, imposing movement restrictions or quarantine measures, culling and vaccinating vary according to local circumstances and from country to country. There is no one solution for all situations, and a balance must be established among effective, feasible and socially acceptable control measures that safeguard the short- and long-term livelihoods of farmers and the health of the population.

In general however, a number of basic measures are common to all situations: infected birds and those in contact with them must be humanely and safely culled to halt spread of the disease, levels of prevention and containment (biosecurity) must immediately be raised appropriate to the level of risk, and surveillance must be increased and widened to permit earlier detection and reporting of disease.

Foot-and-mouth disease (FMD) is an acute infectious disease, which causes fever, followed by the development of blisters (vesicles) – chiefly in the mouth and on the feet. The disease is caused by a virus of which there are 7 types, which all produce similar symptoms. The different types can only be identified in the laboratory.

The virus is present in great quantity in the fluid from the blisters, and it can also occur in saliva, milk and dung. Contamination of any objects with any of these discharges is a danger to other stock. At the height of the disease, virus is present in the blood. Infected animals begin by excreting the virus a few days before signs of the disease develop. Pigs in particular produce large numbers of virus particles.
Airborne spread of the disease can take place and under favourable weather conditions the disease may be spread considerable distances by this route. For example, circumstantial evidence strongly suggests that the outbreak on the Isle of Wight in 1981 resulted from the airborne spread of the virus from Brittany in northern France.
Animals pick up the virus either by direct contact with an infected animal or by contact with foodstuffs or other things which have been contaminated by such an animal, or by eating or coming into contact with some part of an infected carcase. In the past, outbreaks of the disease have been linked with the importation of infected meat and meat products.
The disease is spread mechanically by the movement of animals, people, vehicles and other things, which have been contaminated by the virus. Trucks, lorries, market places, and loading ramps – in or over which infected animals have travelled – are dangerous until disinfected. Roads may also become contaminated and virus may be picked up and carried on the wheels of passing vehicles.

The boots, clothing and hands of a stockman who has attended diseased animals can spread the disease and dogs, cats, poultry, wild game and vermin may also carry infection.

The disease is rarely fatal, except in the case of very young animals, which may die without showing any symptoms. Exceptionally, a severe form of the disease may cause sudden deaths among older stock.

The after-effects of FMD are serious. Affected animals lose condition and secondary bacterial infections may prolong convalescence. The most serious effects of the disease however are seen in dairy cattle. Loss of milk yield will certainly be experienced. Chronic mastitis may develop and the value of a cow is permanently reduced. Abortion, sterility and chronic lameness are commonplace and in some cases chronic heart disease occurs.

There are 7 main types: O, A, C, SAT.1, SAT.2, SAT.3 and Asia 1. Within each type there are many sub-types, e.g. O1 and A22. The average incubation period is 3-8 days but it can be shorter or may extend to 14 days or longer. The virus responsible for the 2001 outbreak in the UK was the highly virulent pan-Asiatic O type. When animals recover from infection by one type of virus they have little or no protection against attacks by any one of the others.

Among farm stock, cattle, sheep, pigs, and goats are susceptible, as are camelids (camels, llamas, alpacas, guanaco and vicuña). Some wild animals such as hedgehogs, coypu, and any wild cloven-footed animals such as deer and zoo animals including elephants can also contract it.

Blisters  (vesicles) in the mouth or on the feet and other signs vary somewhat but can include:
Cattle – Fever, dullness, blowing lightly, off feed, shivering, sudden reduced milk yield and sore teats in milking stock, slavering, tenderness of feet or lameness. Feeding and cudding may cease and the animal is “tucked up” with a staring coat. If at pasture, the animal will be away from the rest of the herd and probably lying down. Quivering of the lips and uneasy movement of the lower jaw with copious frothy saliva around the lips that drips to the ground at intervals. Loss of condition is marked because of the fever and because the mouth is so painful that the animal is afraid to eat.
Sheep and goats – Fever, severe lameness affecting one or more legs, stiff-legged walk, off colour, tendency to lie down and unwillingness to rise, increased lamb mortality. Mouth symptoms are not often noticeable.

Pigs – Fever, sudden lameness, dullness, off feed. Mouth symptoms are usually not visible, but blisters may develop on the snout or on the tongue.

Advice from the Department of Health is that it is spread of FMD to humans is very rare. There has only been one recorded case of FMD in a human being in Great Britain and that was in 1966. The general effects of the disease in that case were similar to influenza with some blisters. It is a mild short-lived, self-limiting disease. The Food Standards Agency have advised that the disease in animals has no implications for the human food chain.

The basic disease control policy is the slaughter of all susceptible animals on premises infected with FMD and dangerous contacts. This is in keeping with EU legislation and OIE guidelines. Movement restrictions are also put in place to help contain the disease.
There is an EU wide ban on the use of prophylactic (routine) vaccination, which has been in place since 1992. This allows EU Member States to retain the highest FMD status under international rules of “countries free from foot-and-mouth disease without vaccination”.
However, the new EU Directive gives greater prominence to the potential use of emergency vaccination in the event of an outbreak as an adjunct to the basic slaughter policy. The Government accepts that emergency vaccination should be considered as a disease control option from the start of any outbreak of FMD.

The UK has its own stocks of 8 different FMD antigen strains held, on its behalf, by a commercial supplier. In addition, the EU Vaccine Bank holds a range of antigens for emergency use.

It can be destroyed by heat, sunlight, low humidity, or certain disinfectants. However it may remain active for a varying time in a suitable medium such as the frozen or chilled carcase of an infected animal or on contaminated objects. Cold and darkness tend to keep it alive. Under favourable conditions it can survive for long periods.

Carcases may be disposed of by commercial incineration, rendering or licensed commercial landfill. Mass pyres will not be used in the future but the use of alternative methods of disposal routes such as on-farm pyres and on-farm or mass burial cannot be completely ruled out if demand exceeds the capacity of the preferred options of incineration/rendering and licensed commercial landfill.

The owner of a suspected animal or carcass must by law report the fact to the Defra Divisional Veterinary Manager. The owner is not expected to diagnose the disease, but he ought to know enough about the disease to suspect it. All owners and stockmen should make themselves familiar with the symptoms, and call in a veterinary surgeon as early as possible; they should never ask another stock-owner to look at the suspected animal because of the risk of cross-contamination.

Restrictions are imposed on the premises from the time of notification prohibiting any animal, person or thing entering or leaving the premises without permission, and a Defra Veterinary Officer (VO) makes an investigation. If signs suggest FMD is present, the VO, after consulting Defra HQ, will sign a notice which prohibits the movement of animals within a radius of 8km of the premises concerned and arrange for sample material from the affected animal(s) to be sent to the Institute of Animal Health, by the quickest possible means, for testing. The Chief Veterinary Officer will confirm the outbreak if the laboratory results confirm the presence of FMD virus.

After the carcasses have been disposed of, a thorough preliminary disinfection of the premises is carried out. The infected place restrictions are maintained prohibiting unauthorised movement on to or off the premises. At an early stage the destruction of vermin on the infected place is arranged to prevent these creatures mechanically carrying infection to other premises in the vicinity. Further cleansing and disinfection are also required.