The swine flu strain H1N2 – very similar to viruses currently circulating in pigs – has been found in a human in the UK for the first time.
The UK Health Security Agency (UKHSA) has detected a single confirmed human case and is working to better understand the new strain and assess the risk to our health.
"It is thanks to routine flu surveillance and genome sequencing that we have been able to detect this virus. This is the first time we have detected this virus in humans in the UK, though it is very similar to viruses that have been detected in pigs," says Meera Chand, incident director at UKHSA.
"We are working rapidly to trace close contacts and reduce any potential spread. In accordance with established protocols, investigations are underway to learn how the individual acquired the infection and to assess whether there are any further associated cases."
There have been about 50 reported human cases worldwide of the H1N2 virus since 2005, none of them related genetically to this strain. This UK case was detected as part of routine national flu surveillance undertaken by the UKHSA and the Royal College of General Practitioners (RCGP).
While there is no need to panic, with the UKHSA working hard to determine how transmissible the strain is or if there are any other cases in the UK, it's useful to be aware of any possible signs or symptoms of swine flu. But first, let's recap what 'swine flu' actually is.
UKHSA has detected a single confirmed human case of influenza A(H1N2)v, which is the first detection of this strain of flu in a human in the UK. We are monitoring the situation closely.
Read more in our news story: https://t.co/TqZ3kt1uEG
— UK Health Security Agency (@UKHSA) November 27, 2023
What is swine flu?
'Swine flu' was the name given to the virus responsible for a pandemic in 2009-2010. It became known as swine flu because it's similar to flu viruses that affect pigs.
"Overall, the outbreak was not as serious as originally predicted, largely because many older people were already immune to it," the NHS website explains. "Most cases in the UK were relatively mild, although there were some serious cases."
The scientific name given to the swine flu strain behind the 2009 outbreak is A H1N1(pdm09), shortened to H1N1. "The relatively small number of cases that led to serious illness or death were mostly in children and young adults – particularly those with underlying health problems – and pregnant women," the health service adds.
The UKHSA points out H1N1 is now circulating in humans seasonally and is no longer referred to as swine flu. "It is distinct from the viruses currently circulating in pigs."
The scientific name given to the strain recently detected in a Brit (similar to viruses currently found in pigs), is A(H1N2)v, or H1N2. The source of their infection remains under investigation, though the PA news agency reports they are not known to have worked with pigs.
Chief Veterinary Officer, Christine Middlemiss, says, "We know that some diseases of animals can be transferred to humans – which is why high standards of animal health, welfare and biosecurity are so important."
H1N1, H1N2 and H3N2 are all major subtypes of swine influenza A viruses in pigs and occasionally infect humans, usually after direct or indirect exposure to pigs or contaminated environments.
Swine flu signs and symptoms
In 2009, swine flu symptoms were detailed to cause:
Other symptoms also listed include a headache, aching muscles, chills, sneezing, a runny nose, loss of appetite, vomiting and diarrhoea.
Looking to the individual in the UK recently found to have the H1N2 strain, the UKHSA reports they experienced "a mild illness" (but have fully recovered). They were tested by their GP after experiencing respiratory symptoms.
Symptoms of respiratory infections, including COVID-19 and the flu, can be very similar, making it harder to identify the type of infection based on symptoms alone.
The specific influenza strain H1N2 is still being looked into. "As is usual early in emerging infection events, UKHSA is working closely with partners to determine the characteristics of the pathogen and assess the risk to human health," the UKHSA states.
However, common symptoms of respiratory infections include:
High temperature, fever or chills
Loss of, or change in, your normal sense of taste or smell
Shortness of breath
Unexplained tiredness, lack of energy
Muscle aches or pains that are not due to exercise
Not wanting to eat or not feeling hungry
Headache that is unusual or longer lasting than usual
Sore throat, stuffy or runny nose
Diarrhoea, feeling sick or being sick
"People with any respiratory symptoms should continue to follow the existing guidance; avoid contact with other people while symptoms persist, particularly if the people they are coming into contact with are elderly or have existing medical conditions," the UKHSA advises.
"UKHSA is monitoring the situation closely and is taking steps to increase surveillance within existing programmes involving GP surgeries and hospitals in parts of North Yorkshire. To assist in the detection of cases and assessment of transmission, those people who are contacted and asked to test are encouraged to do so," it adds.
The UKHSA has also urged pig keepers to report any suspicion of swine fly in their herds to their local vet immediately.
For more information on what to do if you have symptoms of a respiratory infection, see this UKHSA website page. If you are concerned about your symptoms, or they are worsening, seek medical advice by contacting NHS 111. In an emergency dial 999.
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