Nikhil Prasad Fact checked by:Thailand Medical News Team Dec 12, 2025 1 hour, 10 minutes ago
In Spain, H5N1 Circulates in Wildlife While H3N2 Dominates Humans and Swine Flu Circulates in Pigs, Not Forgetting That There Are Many Locals Who Are Immunodeficient Due to HIV
Medical News: Spain Flu Melting Pot Raises Fears of a Dangerous New Variant
Spain is fast becoming one of Europe’s most worrying influenza hotspots, with multiple flu strains circulating simultaneously across humans, animals, and wildlife. Public health experts warn that the unusual convergence of fast-mutating seasonal flu, swine flu activity, and avian influenza outbreaks has created the kind of biological pressure cooker that can sometimes give rise to new recombinant and potentially more virulent flu strains.
A dangerous convergence of human animal and bird flu viruses is putting Spain on high alert for the
emergence of a new influenza threat
As reported in numerous
Medical News coverages, health authorities in Catalonia have already taken the extraordinary step of making masks mandatory in hospitals, health centers, and care homes as influenza cases surge at an alarming pace. According to regional data, flu incidence jumped 2.5-fold in just one week, while hospitals in and around Barcelona report H3N2 cases doubling weekly, overwhelming wards and forcing patients to wait days for beds.
H3N2 Subclade K Is Spreading Fast
The dominant human strain currently circulating in Spain is a mutated H3N2 variant, often referred to by researchers as subclade K. This strain is notorious for its high mutation rate and ability to evade prior immunity. While children and young adults are driving community transmission, the most severe outcomes are being seen among people over 60, with hospital admissions rising sharply.
Doctors across northern Spain describe exhausted staff, corridor beds, and mounting concern as the flu season arrived earlier and more aggressively than expected. Authorities warn the peak is still ahead, coinciding dangerously with Christmas gatherings, a perfect amplifier for viral spread.
Swine Flu Adds Another Layer of Risk
At the same time, Spain has declared a national emergency following the detection of swine flu cases in wild boar, particularly in parts of Catalonia. Although primarily an animal health crisis, swine influenza viruses are of special concern because pigs can act as “mixing vessels,” allowing avian and human flu viruses to exchange genetic material.
Veterinary teams have been deployed to dozens of pig farms, while strict biosecurity measures are being enforced to protect Spain’s pork industry. Scientists stress that widespread swine flu circulation alongside human influenza significantly increases the theoretical risk of viral reassortment.
H5N1 Bird Flu Circulates in Wildlife
Adding to the complexity, H5N1 avian influenza is affecting wildlife across Spain. Around 400 storks were recently found dead n
ear Madrid, triggering investigations into a potentially more virulent bird flu strain. While early tests detected a low-pathogenic virus, the scale of deaths has alarmed authorities.
Across Europe, more than 300 poultry outbreaks have been recorded this year, highlighting sustained viral pressure in bird populations. This Medical News report underscores that when H5N1 circulates in wildlife while H3N2 dominates humans and swine flu circulates in pigs, the ecological conditions for recombination become unusually favorable.
More People in Spain are Immunodeficient Due to rising HIV Infections
Adding to the favorable conditions for a new flu strain to emerge, it has been noted that the rate of HIV has been rising in Spain over the last few years and this is only based on diagnosed cases. They are many silent infected individuals who have yet to be tested. With a large population of immunodeficient individuals in a community that is affected by multiple viruses, the setting could not even be far greater for the viruses to find the perfect missing vessels!
Why Experts Are Concerned
Recombinant flu strains do not emerge often, but when they do, they can carry traits that enhance transmissibility or severity. Spain’s current situation represents a textbook example of overlapping viral reservoirs, intense transmission, and stressed health systems.
While no new recombinant strain has been detected so far, experts urge vigilance, vaccination, mask use in crowded settings, and strong surveillance across human and animal health sectors. What happens in Spain could have implications far beyond its borders if warning signs are ignored.
The coming weeks will be critical. The convergence of multiple flu threats demands coordinated public health action, transparent reporting, and public cooperation to reduce the risk of a far more dangerous influenza scenario unfolding.
Media References:
https://www.theolivepress.es/spain-news/2025/12/08/flu-barcelona-cases-doubling/
https://phys.org/news/2025-12-spain-probes-bird-flu-hundreds.html
https://www.express.co.uk/news/world/2145112/spain-virus-outbreak-national-emergency
https://noticiasambientales.com/animals/this-area-of-spain-plans-to-cull-60000-wild-boars-to-curb-swine-fever/
https://euroweeklynews.com/2025/12/11/catalonia-reintroduces-mandatory-face-masks-worst-flu-epidemic-in-15-years/
https://www.surinenglish.com/malaga/sexually-transmitted-infections-increase-fivefold-malaga-decade-20250904075243-nt.html
For the latest on Influenza or H5N1 news, keep on logging to Thailand
Medical News.
Read Also:
https://www.thailandmedical.news/articles/influenza-or-flu
https://www.thailandmedical.news/articles/h5n1-avian-flu
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