It's winter: the weather is getting colder and with it comes an influx of seasonal cold and flu infections.
The past few months have also seen record cases of Covid, with the highly-transmissible Omicron variant helping cases to skyrocket.
But there's been another outbreak affecting animals across the UK - bird flu, also known as avian influenza.
It's an infectious type of virus that spreads among birds and the current upsurge has been described as the 'largest-ever.'
Around half a million birds have been culled so far, according to UK chief veterinary officer Christine Middlemiss, who said there are 40 infected premises in the UK – including 33 in England.
Read more: Person in England infected with bird flu, UKHSA confirms
In rare cases avian influenza can affect humans - and today (6 January) the UK Health Security Agency (UKHSA) confirmed a person in the South West of England has contracted the disease.
There are lots of different strains of the bird flu virus and most of them don't infect humans, says the NHS.
Here is everything you need to know...
What causes the bird flu?
The Department for Environment, Food and Rural Affairs (Defra) said wild birds migrating to the UK from mainland Europe during the winter months can carry the disease and this can lead to cases in poultry and other captive birds.
How does it spread to humans and is it harmful?
Bird flu is spread by close contact with an infected bird, whether it's dead or alive.
Close contact includes touching infected birds, touching droppings or bedding or killing or preparing infected poultry for cooking
The NHS reassures that you can't catch bird flu through eating fully cooked poultry or eggs, even in areas with an outbreak of bird flu.
While most strains don't infect humans, there have been four variants that have caused concern in recent years: H5N1 (since 1997), H7N9 (since 2013), H5N6 (since 2014) and H5N8 (since 2016).
Although H5N1, H7N9 and H5N6 don't infect people easily and aren't usually spread from human to human, several people have been infected around the world, leading to a number of deaths, the NHS says.
In February 2021 H5N8 was found to have infected a small number of people for the first time, in Russia.
Previously, no humans have been infected with H5N1, H7N9, H5N6 or H5N8 bird flu in the UK.
Defra says the risk to human health from the virus is very low and food standards bodies advise that avian influenzas pose a very low food safety risk for UK consumers.
What are the signs of it in birds?
There are two types of avian influenza, with Highly pathogenic avian influenza (HPAI) being the more serious type. It is often fatal in birds.
Some of the clinical signs of HPAI in birds include:
- a swollen head
- closed and excessively watery eyes
- head and body tremoring
- drooping of the wings and/or dragging of legs
- twisting of the head and neck
- swelling and blue discolouration of comb and wattles
- haemorrhages on shanks of the legs and under the skin of the neck
- loss of appetite or marked decrease in feed consumption
- sudden increase or decrease in water consumption
- respiratory distress
- sneezing
- noticeable increase in body temperature
- discoloured or loose watery droppings
- cessation or marked reduction in egg production.
What are the symptoms of bird flu in humans?
The main symptoms of bird flu can appear very quickly and include:
- a very high temperature or feeling hot or shivery
- aching muscles
- headache
- a cough or shortness of breath
Other early symptoms may include:
- diarrhoea
- sickness
- stomach pain
- chest pain
- bleeding from the nose and gums
- conjunctivitis
It usually takes 3 to 5 days for the first symptoms to appear after you've been infected.
Is there treatment for the bird flu?
If you become ill with the bird flu, you may be given an antiviral medicine such as oseltamivir (Tamiflu) or zanamivir (Relenza).
The NHS says these help reduce the severity of the condition, prevent complications and improve the chances of survival.
They might sometimes be given to people who have been in close contact with infected birds, or those who have had contact with infected people.
There is no bird flu vaccine and the seasonal flu vaccine doesn't protect against bird flu.
What measures are in place?
An Avian Influenza Prevention Zone (AIPZ) came into force across Great Britain on 3 November 2021, and in Northern Ireland on 17 November 2021.
This was extended to include housing measures across the UK on the 29 November 2021 - and it's in place until further notice.
It's a legal requirement for all bird keepers across the UK to keep their birds indoors to limit the spread the disease.
Poultry and captive bird keepers are advised to be vigilant for any signs of disease in their birds and any wild birds, and to seek prompt advice from a vet if they have any concerns.
How do I report suspected cases in birds or humans?
Bird flu is a 'notifiable disease' in animals, meaning you should report any suspected case in animals to the Animal and Plant Health Agency (APHA), even if you're not sure.
Call the Department for Environment, Food and Rural Affairs (Defra) helpline on 03459 33 55 77 if you find dead wild birds.
To prevent infection it is important not to touch or pick up any dead or visibly sick birds that you find.
If you experience any symptoms of bird flu and have visited an affected area in the past 10 days, then call a GP or NHS 111.
A nose and throat swab test can be arranged to check if you have the bird flu.
