What is Bird Flu?

Overview

Bird flu, also known as avian influenza, is a highly infectious disease that affects birds and poultry, including chickens, ducks, turkeys, and geese. The disease can cause a range of symptoms in infected birds, from mild to severe, and can quickly spread from bird to bird, making it a significant threat to poultry farms and wild bird populations.

Bird flu can also infect humans who come into close contact with infected birds, although human-to-human transmission is rare.^1,2,6,9 Bird flu is a viral infection, involving subtypes of the influenza A virus (IAV). In recent years, several highly pathogenic strains of bird flu virus have emerged, including H5N1, H7N9, and H5N6, which can cause severe illness and death in both birds and humans. 

It is important to note that not all these strains have been identified in the UK as yet, and the prevalent subtypes vary from year to year. For example, the most prevalent characterised influenza A virus subtypes in the UK in the week ending 25th January 2024 were H3N2 and H1N1 (a.k.a. swine flu). 

The naming of the virus subtypes (i.e. an H and an N, each followed by a number) refers to the subtypes of two protein markers present on the virus surface (a lipid bilayer), Haemagglutinin (H or HA1-18) and Neuraminidase (N or NA1-11). So, H5N1 means that haemagglutinin type 5 and neuraminidase type 1 are present in the viral envelope. As the influenza virus evolves year on year, different subtypes (combinations of H and N) become dominant.^3,5,6,10 This image shows the various components of the influenza A virus.

Bird flu is caused by the avian influenza (influenza A or IAV) virus, which is a type of - RNA virus that belongs to the Orthomyxoviridae family.^1,3 There are several subtypes of the virus (see above), and some are more virulent than others. Bird flu is primarily spread from bird to bird through direct contact, such as when birds come into contact with each other or contaminated surfaces, or through inhaling infected saliva droplets.

Infected birds can shed the virus in their saliva, nasal secretions, and faeces, which can contaminate feed, water, and other surfaces. People who work with birds or live near poultry farms are at higher risk of being infected with the virus. The disease can also spread through contaminated feathers, eggs, and droppings from infected birds.

Signs and symptoms of bird flu

In birds, the symptoms of bird flu can range from mild to severe and can include (gov.uk):

In humans, the symptoms of bird flu can range from mild to severe, can come on very fast, and can include (NHS):

Main symptoms

• A sore throat
• A very high temperature or feeling hot or shivery
• Aching muscles
• Headache
• A cough or shortness of breath
• Fatigue

Other early symptoms

• Diarrhoea
• Sickness
• Stomach pain
• Chest pain
• Bleeding from the nose and gums
• Conjunctivitis (inflamed eyes due to infection)

Diagnosis

Bird flu is diagnosed through laboratory testing of samples collected from the infected person or bird. These samples may include respiratory secretions, such as mucus or saliva, or blood. These tests can include RT-PCR, viral culture and immunofluorescence (ELISA) assays. The laboratory tests can detect the presence of the avian influenza virus and determine which subtype of the virus is causing the infection.^7,8

Management and treatment of bird flu

The management and treatment of bird flu depend on the severity of the illness and the type of avian influenza virus involved. In birds, the best way to prevent the spread of the disease is to practise good hygiene and biosecurity measures, such as wearing protective clothing and footwear when handling birds and disinfecting equipment and surfaces that come into contact with birds.

In humans, treatment for bird flu typically involves supportive care to relieve symptoms, such as rest, hydration, and pain relief. In severe cases, antiviral medications such as oseltamivir (Tamiflu) or zanamivir (Relenza) may be prescribed to help reduce the severity and duration of illness.

If you suspect that you or your birds have been infected with bird flu, it is important to seek medical attention as soon as possible. If there is a bird infection you must also notify the relevant government department by telephone on 03000 200 301 if you’re in England, 03003 038 268 if you’re in Wales and at your local Field Services Office if you’re in Scotland. Early treatment can help prevent the disease from becoming severe and can improve the chances of a full recovery.

Another important way to manage or prevent severe flu infections altogether is to get vaccinated. Vulnerable groups such as the elderly and people with certain chronic conditions or respiratory problems are routinely contacted by UK healthcare providers to receive seasonal influenza vaccinations in the autumn.

In fact, anyone can get vaccinated at pharmacies, although it may involve paying a small fee if you are not part of a vulnerable group. These specially manufactured vaccines are designed to combat the most likely subtypes or strains of the virus thought to be present in each particular flu season.^4,5 The higher the proportion of a population that is vaccinated, the harder it is for the virus to spread.

FAQs

How can I prevent bird flu? 

To prevent bird flu, it is important to practice good hygiene and biosecurity measures, especially when handling birds or visiting poultry farms. This may include wearing protective clothing and footwear, washing your hands frequently, and avoiding close contact with birds that appear to be sick.

It is also important to avoid consuming undercooked poultry or eggs and to cook all poultry products thoroughly. Taking up the opportunity for seasonal flu vaccination can also be a big help in combatting both the severity and the spread of the disease.

Who is at risk of bird flu?

Anyone who comes into close contact with infected birds, such as poultry farmers, bird handlers, and people who live near poultry farms, is at higher risk of contracting bird flu. People who travel to areas with outbreaks of bird flu are also at increased risk of infection. Groups such as the elderly and people with certain chronic conditions or respiratory problems are particularly vulnerable to severe influenza if infected.

How did bird flu start?

Bird flu is believed to have originated in wild waterfowl, such as ducks and geese, which are natural carriers of the virus. The virus can be transmitted to domestic poultry and other birds through contact with contaminated faeces, feathers, or water.

When should I see a doctor?

If you have been in close contact with infected birds or have symptoms of bird flu, such as fever, cough, and muscle aches, it is important to see a doctor as soon as possible. Early treatment can help reduce the severity and duration of illness and can improve the chances of a full recovery. If you have travelled to an area with an outbreak of bird flu, it is also important to inform your doctor and to seek medical attention if you develop symptoms of the disease.

Summary

Bird flu is a highly infectious disease that mainly affects birds and poultry, including chickens, ducks, turkeys, and geese. The disease can cause a range of symptoms in infected birds, from mild to severe, and can quickly spread from bird to bird, and from bird to human. This makes it a potentially significant threat to poultry farms, wild bird populations and society at large.

It is important to stay informed about the latest developments in bird flu and avian influenza, including any new outbreaks or cases of human infection. By staying informed and taking precautions, getting vaccinated and practising good hygiene, you can help protect yourself, your birds, and your community from the spread of this potentially deadly disease.