Infectious diseasesepidemiology and surveillance

Page content: Key facts | Avian Influenza (AI) | How do people become infected with Avian Influenza? | Does the Avian Influenza virus spread easily from birds to humans? | Personal Protective Equipment (PPE) guidance | Vaccination | Self monitoring by workers | General prevention measures for the general public

Key facts

• Avian influenza (AI), commonly called bird flu, is an infectious viral disease of birds.
• Most avian influenza viruses do not infect humans; however some, such as H5N1, have caused serious infections in people.
• Cases of AI in poultry can take two forms – Highly Pathogenic (HPAI) and Low Pathogenic (LPAI).
• LPAI may infect people but causes only mild disease, including conjunctivitis and influenza-like illness.
• A form of the Highly Pathogenic Avian Influenza, H5N1 virus, which is a different strain to this virus, has caused human cases in various countries and has been associated with direct or indirect contact with infected live or dead poultry. The virus detected recently in poultry in Melbourne is a different virus.

Avian Influenza (AI)

AI viruses are common in wild waterfowl throughout the world, for the most part cycling harmlessly in these well-adapted hosts. Avian influenza outbreaks among poultry occur worldwide from time to time. Avian influenza viruses can be classified into low pathogenicity and highly pathogenic forms based on the severity of the illness they cause in poultry.

Most strains of avian influenza are classified as low pathogenic avian influenza (LPAI) and cause few clinical signs in infected birds.

In contrast, high pathogenic avian influenza (HPAI) causes a severe and extremely contagious illness and death among infected birds with high mortality (up to 100%) in domestic fowl (chickens) and turkeys. In some cases, if LPAI is allowed to circulate in poultry populations, the virus can mutate into the highly pathogenic form. This is why the presence of an H5 or H7 virus in poultry is always cause for concern, even when the initial signs of infection are mild.

LPAI poses no known serious threat to human health, however some strains of HPAI viruses can be infectious to people.

How do people become infected with Avian Influenza?

Direct contact with infected poultry, or surfaces and objects contaminated by their faeces, is presently considered the main route of human infection. As infected birds shed large quantities of virus in their faeces, opportunities for exposure to infected droppings or to environments contaminated by the virus are abundant under such conditions. Exposure is considered most likely during slaughter, defeathering, butchering, and preparation of poultry for cooking.

Does the Avian Influenza virus spread easily from birds to humans?

No. Even with the highly pathogenic H5N1 avian influenza where many thousands of exposures have occurred, cases remain very small.

Personal Protective Equipment (PPE) guidance

Protection of personnel who might come into contact with AI-infected birds is important to the success of the response plan. Whilst the risk of transmission of LPAI is considered low, as a precaution people working on or entering an infected premises or involved in other activities eg. cullers, composters or veterinarians performing field post-mortems should adopt the following protective measures:

• wear appropriate personal protective equipment including foot or shoe covers, respiratory protection (surgical mask) and eye protection
• wash hands before and after handling animals or touching surfaces contaminated by bird secretions (faeces, respiratory secretions or saliva or contaminated products, such as litter)
• ensure response personnel receive the seasonal flu vaccine
• discourage anyone who is ill with a suspected viral infection from entering a poultry house, a response location or processing facility.

Vaccination

It is recommended that anyone exposed to potentially infected birds or contaminated products is vaccinated with the seasonal human influenza vaccine. Although the seasonal human influenza vaccine will not protect against LPAI, it may avoid simultaneous infection with both human and avian influenza. There is a small possibility that if a person is infected with both of these viruses, the viruses could share genetic material (re-assortment) to produce a new and highly infectious virus that would pose a threat to the wider community.

An additional benefit of vaccination is that it will help protect workers from the usual human seasonal influenza and help avoid diagnostic confusion if they develop influenza-like symptoms.

Self monitoring by workers

Workers who have been in close contact with AI-infected birds should monitor their own health during the period of exposure to infected birds or contaminated poultry products, up to seven days after the last exposure.

Self monitoring involves watching for:

• fever (monitor temperature daily for = 38oC)
• respiratory symptoms (e.g. sore throat, cough, difficulty breathing)
• fatigue or collapse due to exhaustion
• chills or shakes
• headache
• muscle or joint aches
• nausea, vomiting, diarrhoea, or
• red, sore eyes (conjunctivitis).

Workers who have been in direct contact with birds or poultry products contaminated with AI and who become ill with any of the above symptoms should:

• report their illness to the workplace management, who in turn should notify public health authorities
• see their local doctor and report that they may have been in contact with birds carrying AI virus
• wear a surgical mask and isolate themselves from others until medically assessed, and
• practice good respiratory hygiene by covering their mouth when coughing or sneezing. Wash their hands after coughing, sneezing, or using tissues or handkerchiefs. Dispose of tissues hygienically.

General prevention measures for the general public

People travelling to areas affected by avian influenza are likely to have only a very small risk of infection. This risk can be reduced further by:

• avoiding places where there may be contact with infected birds, particularly live bird markets
• washing hands thoroughly after any contact with birds, their faeces or body fluids
• ensuring all uncooked poultry and eggs are handled hygienically during food preparation, with careful attention to hand washing after handling.
• ensuring all poultry and eggs are cooked thoroughly before eating.

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 Low Pathogenic Avian Influenza - Fact sheet - January 2012

Authorised by the Victorian Government, Melbourne. To receive this publication in an accessible format or for further health information, phone the Health Protection Branch of the Department of Health on 1300 651 160.