Is swine flu the next pandemic?
In the UK, a person contracts a special form of swine flu for the first time. The worrying thing is that he had no previous contact with pigs. Does this mean that the virus is already circulating undetected in humans?
When a virus jumps from animals to humans, there is initially a lot of excitement. This is because zoonotic pathogens have repeatedly triggered pandemics in the past - most recently the SARS-CoV-2 coronavirus. The current case of a British man who was infected with a rare swine flu variant is therefore causing quite a stir. Infection with this H1N2 variant has never been recorded in the country before, according to the UK Health and Safety Authority (UKHSA). The biggest mystery: how did this person come into contact with the virus in the first place?
But let's start at the beginning: According to the UKHSA, the influenza A(H1N2)v pathogen was discovered during routine surveillance using a PCR test. The person concerned was tested due to respiratory symptoms, had a mild course of the disease and has since made a full recovery.
Since 2005, 50 cases of A(H1N2)v in humans have been reported worldwide. Most recently, the virus variant was diagnosed in an 18-year-old American this August after he came into contact with pigs at an agricultural fair. However, according to the British health authority, neither this nor the previous cases were of the same strain as the British man who fell ill. At the same time, the virus is similar to that in British pigs.
Zoonotic infections pose a risk
The UKHSA is currently trying to trace the contacts of the infected person in order to prevent the possible further spread of the virus. But more importantly, the authority wants to identify the source of the infection. In contrast to previous cases, the Briton had no contact with pigs. Does this mean that the virus is already circulating undetected in humans?
Normally, swine flu viruses overcome the species barrier by infecting people who are in close contact with animals. This is why, for example, people who work with chickens are regularly tested for bird flu. In rare cases, influenza viruses that occur in birds or pigs could also trigger symptomatic infections in humans, explains the Robert Koch Institute (RKI). But even if the virus manages to make this leap, in the vast majority of cases it is the end of the story. As it is not adapted well enough to human cells, it cannot spread from person to person.
Nevertheless: "In the case of zoonotic infections, there is always a risk that the viruses - which are unknown to the human immune system - will adapt to humans," writes the RKI. "If such viruses acquire the ability to be transmitted from person to person, they can trigger a pandemic."
"You can never be completely sure"
However, according to experts, there is currently no reason to panic. "Overall, there is no evidence that influenza A(H1N2) causes more severe illness than other, more commonly circulating influenza types," says Paul Hunter, Professor of Medicine at the University of East Anglia. "Human-to-human transmission also does not appear to be very efficient, and sustained human-to-human transmission has not yet been reported."
Martin Michaelis, Professor of Molecular Medicine at the University of Kent, also believes a pandemic is unlikely. The case of swine flu discovered in the UK was "mild", he explains - but adds: "You can never be completely sure, as mutations can occur that change the nature of this strain of the virus if it continues to spread in humans." The infection of a human with the swine flu virus H1N2 is a stark reminder that influenza viruses that spread between different species pose a constant risk to humans, the expert said.
Not all influenza viruses are the same
A(H1N2)v is a subtype of the influenza A virus. Influenza A viruses have been identified in seven different species, including humans, birds and pigs. However, they normally remain within their species. This is because animal influenza viruses differ from human influenza viruses and, according to the World Health Organization (WHO), cannot be easily transmitted to humans and between humans.
The strain now discovered in the British patient is therefore not the same virus as H1N1, which triggered the swine flu pandemic in 2009. H1N1 contained genetic material from viruses that circulated in pigs, birds and humans in the 1990s and 2000s. It now circulates seasonally in humans and is no longer referred to as swine flu. It is different from the viruses currently found in pigs.
The discovery of the H1N2 swine flu variant in a British individual without any contact with pigs raises concerns about potential undetected circulation of the virus in humans, highlighting the ongoing risk posed by zoonotic infections. Meanwhile, experts stress that while pandemics are always a possibility with unknown viruses adapting to humans, there's currently no evidence suggesting that H1N2 causes more severe illness or has effective human-to-human transmission.
Source: www.ntv.de
