Bird flu is similar to Swine flu, dog flu, horse flu and human flu as an illness caused by strains of influenza viruses that have adapted to a specific host. Out of the three types of influenza viruses (A, B and C), influenza A virus is a zoonotic infection with a natural reservoir almost entirely in birds. Avian influenza, for most purposes, refers to the influenza A virus.
Though influenza A is adapted to birds, it can also stably adapt and sustain person-to-person transmission. Recent influenza research into the genes of the Spanish flu virus shows it to have genes adapted from both human and avian strains. Pigs can also be infected with human, avian, and swine influenza viruses, allowing for mixtures of genes (reassortment) to create a new virus, which can cause an antigenic shift to a new influenza A virus subtype which most people have little to no immune protection against.
Bird flu strains are divided into two types based on their pathogenicity: high pathogenicity (HP) or low pathogenicity (LP). The most well-known HPAI strain, H5N1, appeared in China in 1996, and also has low pathogenic strains found in North America. Other Bird flu strains that have caused concern in recent years include H7N9, H5N6 and H5N8.
On the eve of the UK/2019 General Election the The Sun newspaper of Wednesday 11th December 2019 headlined a warning: "Devastating outbreak of flu-like illness could kill 80 million people across the world in less than two days, experts warn".
How does it affect humans?
Bird flu is unique in that it can be transmitted directly from birds to humans.
Infected birds shed the virus in their saliva, mucous and faeces so it can infect people if it gets into the eyes, nose, mouth - or even inhaled.
This might happen when virus is in the air - in droplets or possibly dust - and a person breathes it in, or when a person touches something that has the virus on it and then touches their mouth, eyes or nose.
Most Bird flu infections in people have happened after unprotected contact with infected birds or contaminated surfaces.
But in some cases no direct contact has been reported.
No human Bird flu infections have been reported from proper handling of poultry meat or from eating properly poultry products and it can't be passed from person to person.
However, if the virus mutates into a form that can be passed between humans, it could result in the infection spreading rapidly across the globe.
This happened during the great influenza pandemic of 1918/19 when a new influenza virus subtype emerged and killed around 50million people in six months when it spread around the world.
How can you prevent bird flu?
It's important to note that the seasonal flu vaccine doesn't protect against Bird flu.
Those who work with chickens or are visiting a country that has had a recent outbreak should wash their hands often and avoid contact with live birds and poultry.
Cooking with different utensils for cooked and raw meat, and making sure it's cooked until steaming hot will help prevent catching the virus.
Health bosses also warn people not to go near or touch bird droppings or sick and dead birds.
It's also advisable to steer clear of raw eggs, live animal markets and undercooked or raw poultry.
What are the symptoms?
The main symptoms of bird flu can appear very quickly and include:
- A very high temperature or feeling hot or shivery
- Aching muscles
- A cough
Other early symptoms may include:
- Stomach pain
- Chest pain
- Bleeding from the nose and gums
It usually takes three to five days for the first symptoms to appear after you've been infected.
Within days of symptoms appearing, it's possible to develop more severe complications such as pneumonia and acute respiratory distress syndrome.
Getting treatment quickly, using antiviral medicine, may prevent complications and reduce the risk of developing severe illness.
Call a GP or NHS 111 if you experience any symptoms of bird flu and have visited an area affected by Bird flu in the past 10 days.
- "Influenza - Human and Avian (Fact Sheet)"
- "Chapter Two : Avian Influenza by Timm C. Harder and Ortrud Werner"
- "Transmission of Influenza Viruses from Animals to People"
- "H5N1 avian influenza: Timeline of major events"
- "Bird flu outbreak in Suffolk could spread to people – the signs to watch out for"