1. What is avian influenza?
2. How is avian influenza transmitted?
3. What role does the movement of poultry play?
4. Are poultry droppings dangerous?
5. How long does the virus live in bird/animal droppings?
6. Can animals "shed" the virus before clinical signs are observed?
7. What are the signs of HPAI in poultry?
8. What should be done if a dead bird is found?
9. What precautions should be taken in a areas affected by avian influenza?
10. What should be done when an outbreak occurs?
11. What is the most effective way of containing the avian influenza virus?
12. What can be done to limit spread of the disease?
13. What are the best methods of decontamination?
14. Does avian influenza pose a threat for people?
15. How do people become infected with avian influenza?
16. Could avian influenza become an influenza pandemic?
17. Why is there so much concern about the current outbreaks?
18. Is it safe to eat poultry and poultry products?
19. Is it safe to pick up or handle feathers?
20. What can farmers and other poultry handlers do to protect birds?
1. What is avian influenza?
Avian influenza (AI) is a contagious disease of animals caused by a virus which normally infects birds. Although it is not common, the virus can also infect humans who have prolong close exposure to the virus.
AI has multiple strains or types and can be divided into highly pathogenic (HPAI) and low pathogenic (LPAI) strains based on its ability to cause disease in poultry.
Low pathogenic avian influenza is a natural infection of waterfowl that may cause minimal to no signs of disease in domestic poultry and wild birds and is not a serious threat.
Highly pathogenic avian influenza was earlier believed to cause severe disease only in domestic poultry, but has recently also caused serious disease in waterfowl with a high death rate, often within 48 hours.
2. How is avian influenza transmitted?
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.
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 egg shells (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).
3. What role does the movement of poultry play?
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.
4. Are poultry droppings dangerous?
Poultry droppings could be dangerous for other animals and for people because infected poultry excrete the H5N1 virus (and other potentially dangerous pathogens) in their droppings.
It is impossible to avoid other chickens coming into contact with droppings from infected chickens in the same flock, but you can protect different species by keeping them in separate enclosures.
Poultry droppings are also widely used in agriculture and aquaculture as fertiliser and food for other animals such as pigs and fish. However, untreated droppings can be a significant way of passing on the disease. Even the collection and transport of untreated or non-composted poultry manure could be a highly effective way of spreading the virus.
People can come into contact with poultry droppings in two ways: directly through their skin and indirectly through clothing or equipment. Always try to wear gloves, boots and other protective clothing if you are going to be in places where poultry are kept (or have been kept recently) such as enclosures, coops, sheds or other buildings. When you leave, take your gloves, boots and protective clothes off and wash your hands thoroughly with soap (or scour them vigorously with ash if no soap is available), disinfecting them afterwards if possible. It is even more important to wash and disinfect thoroughly if you have not been wearing gloves or other forms of protection.
5. How long does the virus live in bird/animal droppings?
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.
6. Can animals "shed" the virus before clinical signs are observed?
The incubation period is the time between infection and the appearance of signs of disease. "Shedding," as it applies to viruses, means that the animal's secretions and/or droppings contain viral particles that may infect other animals or people. Some animals (e.g., growing poultry) rapidly show clinical signs of disease and simultaneously shed virus. Other infected animals, including some species of waterfowl, may appear clinically healthy, but be shedding the virus. The incubation and shedding periods for avian influenza virus in many species are not known.
7. What are the signs of HPAI in poultry?
The severity of signs depends upon the strain of virus and the type of bird infected. Birds infected with highly pathogenic avian influenza may die suddenly or show a range of clinical signs including respiratory difficulty, diarrhoea, swollen heads, dullness, a drop in egg production, and a loss of appetite. Some birds, especially waterfowl, can be infected with low pathogenic avian influenza without showing any signs of disease.
Any the following signs (either alone or together) could indicate that your poultry is affected by avian influenza:
• lack of coordination (including inability to walk or stand straight)
• ruffled feathers
• difficulty in breathing
• loss of appetite
• depression and droopiness
• bluish colouring of wattles and comb
• edema and swelling of head, eyelids, comb, wattles, hocks
• watery diarrhoea
• pin-point haemorrhages (mostly visible on feet and shanks)
• bloody or watery discharge from nose or beak
• sudden fall in egg production
• eggs with soft or deformed shells
Many of these signs could also indicate Newcastle disease, so you should seek veterinary advice to establish the exact nature of the disease affecting your poultry. The veterinarian should take samples or even a few birds for further analysis to a laboratory.
You should not sell or move the birds from their houses or coops. If you do so, you may face a severe fine or, even worse, spread the disease to other areas.
8. What should be done if a dead bird is found?
Do not touch any dead animals. Report the finding to the local veterinary or public health authorities who will take the appropriate step to remove the bird and arrange for an autopsy to determine the cause of death.
9. What precautions should be taken in a areas affected by avian influenza?
Immediately report sick or dead birds to the local veterinary (or public health) authorities or community leaders. It is important that all signs of illness or sudden and unexplained deaths in poultry and wild birds are reported to the authorities so that they can deal with them safely and help stop the virus spreading.
Keep all birds separate from people and living areas. Close contact with infected birds can put you and your family at risk.
Wash your hands often to kill and remove the virus. You should always do so after handling birds, cooking or preparing poultry products, and before eating.
Eat well-cooked poultry products.
Do not eat sick or dead chickens and do not give or sell them to others. Keep chicken from infected flocks out of the food chain and do not feed them to other animals.
Seek immediate treatment from your doctor if you have fever after being in contact with sick or dead poultry.
10. What should be done when an outbreak occurs?
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.
11. What is the most effective way of containing the avian influenza virus?
The most effective means of containing the avian influenza virus is to ensure adequate biosecurity at all stages of the poultry production and distribution cycle. One key element of biosecurity is to eliminate contact between poultry and wild birds in order to reduce the risk of wild birds passing on the virus to poultry, but also of the virus escaping from infected poultry into the wild. This is particularly important to prevent the genesis of highly pathogenic strains of avian influenza virus because scientific research has shown that some low pathogenic strains of avian influenza virus carried by wild birds have mutated into a highly pathogenic strain in poultry operations.
12. What can be done to limit spread of the disease?
Avian influenza usually spreads when live birds carrying infection are bought and sold, and through bird droppings on dirty equipment, cages, feed, vehicles or shoes/clothing. Practising good hygiene (biosecurity) is therefore an extremely important safety measure to prevent infection entering domesticated poultry.
Once HPAI has been recognised in a trading environment or country, all persons working with poultry should greatly increase the level of safe hygienic practices to avoid bringing the virus in (bio-exclusion) or allowing the virus to leave (bio-containment) if it has already entered a flock, village or region.
The main ways in which virus can enter an area are:
• bringing in live birds
• bringing in objects such as animal/bird cages that have not been washed and disinfected
• bringing in feed that has been contaminated
• bringing in contaminated footware and clothing
• bringing in vehicles
The main ways in which virus can leave an area are:
• sale of infected birds to markets
• exit of wild waterfowl which have visited infected backyard poultry units
• people working with or selling sick poultry
• taking dirty footware, clothes, cages, etc. to markets or other bird farms/production units
The basic principle of bio-exclusion is to be aware of the various routes by which virus can enter and maintain a high level of vigilance on these routes until the period of risk is over.
The basic principle of bio-containment is to keep infection within poultry units, thereby reducing risk to neighbouring flocks, villages, zones and regions, and cooperate with the authorities in disease response measures.
13. What are the best methods of decontamination?
Soapy water and detergents are the first choice because the avian influenza virus is more simple to destroy than many viruses: it is very sensitive to detergents which destroy the fatty outer layer of the virus, and this layer is needed to enter cells of animals. Water alone may be insufficient because the virus survives well in water and simple washing may only help it enter areas where it can be picked up by other birds.
For extra protection it is advisable to use disinfectants, particularly in areas known to be affected by avian influenza. Disinfection helps prevent the mechanical spread of disease agents from one location to another by people, equipment and or supplies. Before leaving a site, adequately dispose of non-reusable materials, and disinfect clothes and boots and all equipment to the extent possible. Care should be taken to decontaminate all objects that have come in contact with potentially infectious materials, e.g., surgical instruments, clothing, cages, restraint or capture equipment, vehicles, boots, etc.
One of the more difficult organic materials to disinfect and dispose of is bird droppings: the virus is maintained in moist, dirty conditions so it is essential to thoroughly disinfect items (such as cages, shoes and clothes) that have been in contact with these droppings before working with poultry or entering a place where poultry are kept.
14. Does avian influenza pose a threat for people?
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 (http://www.who.int/csr/disease/avian_influenza/en/index.html), indicating that the transmission of the virus from poultry to people remains inefficient.
15. How do people become infected with avian influenza?
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.
16. Could avian influenza become an influenza pandemic?
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.
17. Why is there so much concern about the current outbreaks?
There is concern that the virus may change (reassort or mutate) to emerge as a new virus that is easily transmissible between people and capable of causing disease in people, birds and other animals. Influenza A viruses occur worldwide in a wide range of animals, including humans.
The high pathogenic H5N1 avian influenza strain involved in most of the outbreaks during the last 18 months has shown the ability to jump the species barrier occasionally and cause severe disease, with high fatality, in humans. It has not shown the capacity to transmit between humans.
Avian and human influenza viruses can exchange genetic material when a person or other animal susceptible to infection is simultaneously infected with these viruses. This could create a completely new subtype of the influenza virus to which few, if any, humans would have immunity and which might be able to spread between humans.
18. Is it safe to eat poultry and poultry products?
Yes, but certain precautions should always be followed to ensure that the meat and animal products we eat come from healthy animals. Poultry and other birds that have been ill and died should not be eaten nor given as feed to other animals. Only consume meat or products from healthy birds.
In areas free of the disease, poultry and poultry products can be prepared and consumed as usual (following good hygienic practices and proper cooking), with no fear of being infected by the H5N1 virus.
In areas experiencing outbreaks of HPAI, poultry and poultry products can also be safely consumed provided they are properly cooked and properly handled during food preparation. Consumers need to be sure that all parts of the poultry are fully cooked (no "pink" parts) and that eggs are properly cooked (no "runny" yolks); this kills not only the virus but also other important disease-causing microbes.
In areas affected by the H5N1 virus, certain customary practices such as drinking raw blood or raw embryonating eggs should be discouraged if not prohibited.
It is always a good idea to wash the outer surface of eggs with water and some soap to remove any dirt or faecal matter before storing or using. Also, remember that raw eggs used as an ingredient in sauces, cakes or other foodstuffs are always a potential source of disease-carrying microbes.
Consumers should also be aware of the risk of cross-contamination. When preparing food, juices from raw poultry and poultry products should never be allowed to touch or mix with items eaten raw. When handling raw poultry or raw poultry products, persons involved in food preparation should wash their hands thoroughly and clean and disinfect surfaces in contact with the poultry products. It is sufficient to use soap and hot water.
Avian influenza is not transmitted through cooked food. To date, no evidence indicates that anyone has become infected following the consumption of properly cooked poultry or poultry products.
19. Is it safe to pick up or handle feathers?
Yes. The probability of humans being infected with avian influenza directly from birds is extremely low (even though there have been cases of villagers in Azerbaijan who reportedly contracted the disease after plucking feathers from dead infected swans). To be on the safe side, children should not pick up or handle feathers or dead birds. If they come into contact with birds in an area not affected by HPAI, it is always wise for them to wash their hands properly.
20. What can farmers and other poultry handlers do to protect birds?
One of the most common breaks in biosecurity for many transboundary animal diseases, including HPAI, is people bringing contaminated materials and equipment (clothes, shoes, transport, crates, trays, feeders, cages, etc.) or animals into areas where healthy animals are kept, or taking such materials or sick animals out of areas that are infected. Avian influenza viruses can enter or leave places where poultry are housed in three major ways: through people, through materials and through animals themselves.
Prevent contamination via people
• Do not allow strangers access to places where animals are housed.
• Provide protective clothes (including boots) to those that visit poultry farms/premises.
• Provide baths with disinfectant for boots (use a pre-disinfectant bath to wash off organic matter before entering disinfectant) or keep boots clean after each use; do not use boots for other purposes outside poultry houses or areas.
• Ideally, all farm workers and wanted visitors should take a full shower and use clothes from the farm/premises before entering areas where poultry are kept; once used, these clothes should not leave the farm/premises.
• Producers who use outside workers for assistance on their farms/premises, should ensure that these workers do not have poultry of their own
• Animal health officials visiting affected farms/premises should be extremely aware that, through their work in epidemiological investigations or vaccination initiatives, they could actually be spreaders of infection and disease.
• Producers should always know where their feed and water come from; the quality of these should be checked periodically.
Prevent contamination via materials
• Before entering a farm/premises, clean and disinfect all equipment and instruments that will be used; do the same when leaving.
• Remember that porous materials, such as wood and fibre, are more difficult to disinfect than materials such as metal or plastic.
Prevent contamination via animals
• Ensure that any animals to be introduced to the farm/premises are healthy; if possible, a health certificate should be obtained and displayed.
• Vaccinate only healthy animals.
• Establish a quarantine area where new animals can be housed and not come into contact with poultry already on the farm/premises; these housing areas should be separated from each other as much as possible.
• Use separate workers to handle new and existing animals; if this is not possible, handle or feed the new animals last.
• Keep newly added birds separate from existing birds for 15-30 days.
• Find ways of keeping wildlife out of poultry farms/premises (e.g. enclosures and nets).
• Find ways to stop cats, dogs, rats and other vermin from entering areas where poultry are raised or lay eggs.