Britain was today rocked by fears of a new swine flu after someone fell ill with a disease never seen here before.
Officials don’t know how the unidentified Briton became infected with H1N2, leading some experts to worry the disease could be spreading under the radar.
Bosses at the UK Health Security Agency (UKHSA) are doing their best to contain the virus.
All contacts of the person who has fully recovered from a ‘mild’ illness are traced.
How deadly is swine flu? Are the symptoms different from normal flu? And isn’t the disease already circulating in Britain? Here, MailOnline explains everything you need to know about the species.
Officials don’t know how the unidentified Briton became infected with H1N2, leading some experts to worry the disease could be spreading under the radar. Bosses at the UK Health Security Agency (UKHSA) are doing their best to contain the virus. All contacts of the person who has fully recovered from a ‘mild’ illness are traced
The strain can be transmitted from sick pigs to people, but only rarely spreads between people. The infected Briton is not known to have worked with pigs, but has now fully recovered
What is H1N2?
H1N2 is a specific variant of the Mexican flu. Like human flu viruses, there are different types.
Swine flu is usually caused by three main subtypes: H1N1, H1N2 and H3N2.
A variant of H1N1 caused the 2009 swine flu pandemic, killing thousands of people around the world.
However, this specific subtype is still circulating among humans and is no longer referred to as ‘swine flu’ due to its specific genetic makeup.
How deadly is it?
Since 2005, only 50 human cases of H1N2 have been reported worldwide.
But none of them have been to Britain. Furthermore, none are genetically related to this specific species.
Since the 2009 swine flu crisis, fatalities have occurred sporadically worldwide due to the transmission of viruses from pigs to humans.
An independent review of the UK’s response to the pandemic confirmed that 457 deaths were caused by swine flu in the country.
But the mortality rate – the percentage of patients who died from the disease – was estimated at about 0.02 percent. By comparison, when Covid first hit, it had a mortality rate of up to three percent.
How fast does it spread?
It is not known at this stage how transmissible the strain is or whether there could be other cases in Britain.
However, the virus only rarely spreads between people.
Instead, most cases occur in people exposed to infected pigs, such as visitors to rural fairs and farmers.
Bosses at the UK Health Security Agency (UKHSA) said they were ‘working quickly to trace close contacts and reduce any potential spread’.
Where does it spread?
The case was discovered after the Briton, believed to be living in North Yorkshire, tested positive after visiting his GP with ‘respiratory complaints’.
But health chiefs have not yet identified the source of the infection and have opened an investigation, the UKHSA said.
The UKHSA said it is now ‘monitoring the situation closely’ and has expanded its swine flu surveillance programme, involving GP practices and hospitals in North Yorkshire.
They have also urged anyone with ‘respiratory complaints’ to stay at home and avoid any contact with others until the disease has cleared.
What are the symptoms of H1N2?
For most people, swine flu is mild. It occurs quickly and usually lasts about a week.
The virus often causes fever, fatigue, coughing and sore throat.
Other symptoms may include headache, muscle aches, chills, sneezing, a runny nose, loss of appetite, vomiting and diarrhea.
But cases are normally mild and go away on their own. Mortality rates are generally low.
However, scientists say children under five, people over 65, pregnant women and people with underlying health conditions are at greater risk of complications if they become infected.
How is it different from the 2009 swine flu outbreak?
That variant, scientifically known as H1N1(pdm09), contained genetic material from viruses circulating in pigs, birds and humans.
Swine flu is of concern because pigs can act as ‘mixing vessels’ and can contain viruses of different species at the same time. As such, genetic material can mix to create a hybrid virus in a process called assortment.
That was the trigger for the 2009 pandemic.
It is not yet known which genes the H1N2 strain circulating in Britain carries.
How does swine flu spread?
As with any flu, when infected pigs cough, sneeze or even breathe, droplets containing bits of flu can spread through the air.
If these get into a person’s nose and mouth or are inhaled, they can become infected.
Swine flu among pigs increases around autumn, increasing the risk of the disease spreading to humans.
The virus can survive for several weeks in carrier pigs without showing clinical symptoms. These carrier pigs can then be a source of infection for other pigs.
It can also be spread by wild animals and birds or indirectly through contaminated equipment, clothing, food or water.
It has not been shown that it can be transmitted through eating pork and other products derived from pigs. However, pigs have been culled for similar viruses.
Health officials say the most effective way to reduce transmission is to follow simple respiratory and hand hygiene.
How can swine flu be treated?
Most people cannot be sure that they have had swine flu without laboratory test confirmation.
This requires PCR tests, such as those used to detect Covid.
During the 2009 crisis, people with swine flu were often treated with the antiviral drug Tamiflu. But follow-up analysis suggested the drug worked no better than remedies like paracetamol.
The NHS still says Brits can be given Tamiflu (known as oseltamivir) or Relenza (zanamivir) if they catch bird flu, which is considered another variant of the flu threat.
It says: ‘Antiviral medications help reduce the severity of the condition, prevent complications and increase the chances of survival.
‘They are sometimes also given to people who have been in close contact with infected birds, or to people who have had contact with infected people, for example family or healthcare staff.’