Spain reports a human case of swine flu A(H1N1)v. in Catalonia

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The Health Alerts and Emergencies Coordination Center has reported a human case of swine influenza due to the A(H1N1)v virus.

It was this January 10 when the health authorities of Catalonia reported a case of swine flu in a 33-year-old man who works on a pig farm in the province of Lleida, as Animal's Health has learned.

The symptoms began on November 25, 2023 and it was on December 12 when a sample of nasal and oropharyngeal exudate was taken, which was positive for influenza A, but could not be subtyped.

The sample was sent to the regional reference laboratory of Catalonia where it was identified as swine influenza virus A(AH1N1)v.

In this sense, no secondary cases have been detected among close family contacts or among the 9 farm workers studied. In addition, it is reported that the case has evolved favorably.

In any case, the sample was sent for confirmation to the National Institute of Microbiology and the isolated virus will be shared with the WHO Collaborating Center.

https://www.animalshealth.es/profesionales/espana-informa-caso-humano-gripe-porcina-cataluna

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Translation Google

They confirm an infection of swine flu in a farm worker in Lleida

MARGA CASTILLO
7 FEB. 2024 - 11:51

After confirming a case of swine flu in a person in Catalonia, experts point out that these episodes occur from time to time, so the true incidence of the transmission of swine viruses to humans is not known exactly and we must activate the maximum surveillance systems to minimize the chances of a new pandemic.

The European Center for Disease Prevention and Control (ECDC) has reported a case of swine flu infection in a worker at a farm in Lleida, without further related cases having been identified in the area, and after passing the illness he is in good health. The Department of Health recommends flu vaccination for people who work on farms, poultry or swine operations, or are in contact with wildlife .

The contagion was reported by the Spanish authorities on January 29 and was published in the ECDC bulletin corresponding to the week of January 28 to February 3. After being diagnosed with bronchitis , it has been confirmed that it is swine flu A (H1N1 subtype). The patient has fully recovered and no new cases have been detected among close contacts or among co-workers at the farm, which would be an isolated case.

The last similar case in Spain occurred in 2022 in a person from Navarra who also had contact with infected pigs. Since 2011, 19 cases have been reported in Europe and a total of 73 worldwide .

Cases of swine flu viruses infecting humans and vice versa are relatively common in people who have contact with infected animals. It should not be a social alarm as long as we are vigilant against possible new 'recombinant' viruses or new viruses with mutations. "That is why it is very important to be vigilant," explains María Montoya, researcher in the Viral Immunology: Therapies and Vaccines group at the Margarita Salas Biological Research Center (CIB-CSIC).

The natural reservoirs of the influenza virus are waterfowl . The different flu viruses are capable of infecting birds and mammals, including people and pigs, but it also infects sea lions, seals, horses or dogs , among others, recalls this expert on the Science Media Center platform ( SMC).

The risk of genetic recombination

The flu viruses that infect people and pigs often have many similarities and can jump from people to pigs easily. In fact, there are human flu viruses on a pig farm. People who have more contact with these animals, such as farm workers, can transmit the viruses to the animals and become infected with the flu viruses that pigs carry. In fact, the virus of the first pandemic of the 21st century was a swine flu virus , an H1N1.

The risks to the community are the same as those of circulating flu viruses. The problem arises when one of the swine or human viruses recombines with another flu virus . From there, new viruses emerge, such as the 2009 H1N1 pandemic virus. To prevent community risks, the most important thing is to carry out epidemiological surveillance of circulating viruses on farms and people who are in contact with sick animals. In this way, the necessary measures can be implemented to protect animals and people.

The swine flu virus commonly circulates in pig populations. It can sporadically be transmitted to humans, mainly personnel who are in direct contact with animals. It cannot be transmitted by consuming pork products, so there is no risk of food infection. When this jump occurs it is not normally transmitted between humans; It has a low capacity for person-to-person transmission and the symptoms are usually mild or similar to those of a common flu, which is why it can often go unnoticed, point out José Ignacio Núñez and Llilianne Ganges, researchers at the Institute of Agri-Food Research and Technology (IRTA). )

A different case was what happened with the 2009 pandemic influenza A (H1N1) virus . This virus, which featured segments of avian, human and porcine viruses, jumped to humans causing a pandemic. It was distributed globally and humans have transmitted it to the pig population. "In 2021, a scientific article was published by a group in China that had identified a virus circulating in pigs with pandemic potential, but since then no outbreak has been reported in humans. In any case, it is essential to know the viruses that are circulating in pig populations to analyze their genome.

"Influenza or swine influenza type A is endemic throughout the world and in Spain, the leading pig producer in Europe, up to four different subtypes of this virus circulate: H1N1, H1N2, H3N1 and H3N2. There is a certain affinity between swine viruses. swine and human flu and, in fact, perfectly documented reciprocal transmissions have occurred since this infectious disease has been known. When the genetic composition of the different human and swine flu viruses is analyzed, this infectious promiscuity becomes evident," adds Gustavo del Real, researcher at the National Institute of Agricultural and Food Research and Technology (INIA-CSIC).

"·In any case, this specific case is a new warning that it is perfectly possible and not very unlikely, the stable introduction of new strains of swine flu , directly or through their combination with human strains, in the human population with the risk of causing a new pandemic like the one that occurred in 2009. Therefore, it is essential to implement epidemiological surveillance programs specifically designed to immediately detect this type of zoonosis in order to stop and/or prevent outbreaks that lead to epidemics or pandemics. of incalculable consequences ."

Are there likely to be more cases?

Not likely; Humans can sporadically become infected with swine influenza viruses circulating in pig farms, but this is not common. Likewise, personnel in contact with animals must maintain biosafety measures and it is recommended that they receive vaccination against influenza, which reduces the probability of infection. On the other hand, the capacity for transmission from person to person is very small.

What risks are there for the community?

Due to this low transmission capacity between humans, it does not pose a special risk. The symptoms can vary from mild to those produced by the common flu, so it is not expected to constitute a relevant problem.

Are these cases of humans affected by the A(H1N1) virus common?

The pandemic A(H1N1) virus has circulated seasonally in humans since it emerged in 2009 and was distributed globally. Subsequently, it was man who transmitted the virus to pig populations where it also circulates, now predominantly, along with the usual pig subtypes.

https://www.expansion.com/directivos/estilo-vida/salud/2024/02/07/65c3514e468aebcf308b458f.html

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European Centre for Disease Prevention and Control

Communicable disease threats report, 28 January - 3 February 2024, week 5

Communicable disease threats report, January 28 - February 3 2024, week 5 - EN - [PDF-1.66 MB]

Excerpt:

3. Human infection with swine influenza A(H1N1) variant virus – Spain – 2024

Overview:

On 29 January 2024, the Spanish authorities reported a possible case of human infection with swine influenza
A(H1N1) variant virus (A(H1N1)v) in an adult male worker in a pig farm. The patient has no history of underlying
conditions, lives in the Region of Catalonia and developed symptoms (cough with muco-purulent expectoration,
fever, malaise and myalgia) on 25 November 2023. He contacted an outpatient clinic three times within three
weeks from the start of the symptoms. There were no signs of pneumonia following chest x-ray and the patient
was diagnosed with bronchitis. On 12 December 2023, a nasal and oropharyngeal exudate sample tested positive
for influenza A, which could not be subtyped. It was further analysed in the regional reference laboratory in
Catalonia and was identified as swine influenza A(H1N1)v. The sample was sent for confirmation to the National
Institute of Microbiology and the virus isolate will be shared with the WHO Collaboration Centre.

The patient has fully recovered. To date, no new cases have been detected among close contacts (family
members) of this case, nor among co-workers in the farm through the epidemiological investigation, which
according to Spanish authorities, is considered closed.

The sequences are available on GISAID (isolate ID: EPI_ISL_18782577). According to the assessment by ECDC
experts all genes match currently circulating swine viruses.

Background: overall, and since 2011, 73 cases of A(H1N1)v infection have been reported globally, from Brazil (2),
Canada (1), China (42), Denmark (2), Germany (5), Italy (1), the Netherlands (6), Spain (2), Switzerland (3) and
the United States (9). In 2023 (by year of diagnosis or onset), six cases of A(H1N1)v were reported, including two
cases detected in EU/EEA countries: Spain (1) and the Netherlands (1). The previous case in Spain was reported
with date of onset in 2022.

Source: EWRS notification

ECDC assessment:

Sporadic transmission of influenza viruses of swine origin to humans causing mild to severe infections have been
reported from several countries, including in the EU/EEA. Swine influenza viruses circulate widely in the pig
population and direct human exposure to pigs represents the most common risk factor for infection. Therefore, this
A(H1N1)v case from Spain is not unexpected. Cases have also occurred among otherwise healthy people and
sporadic infections cannot be excluded when people have unprotected direct contact with infected animals.
When a human infection is detected, it is necessary to perform contact tracing to exclude onward transmission to
contacts and to implement control measures to prevent human-to-human spread. Zoonotic influenza viruses
isolated from patients should be further sequenced and characterised, as well as shared with the national influenza
reference laboratories and WHO Collaborating Centres.

The overall risk of spread of this type of influenza is very low for the general population and low for occupationally
exposed individuals due to the high prevalence of swine influenza viruses in the pig population. Sporadic cases can
be expected.

ECDC published a Testing and detection of zoonotic influenza virus infections in humans in the EU/EEA, and
occupational safety and health measures for those exposed at work in October 2022 and Threat Assessment Brief
on Eurasian avian-like A(H1N1) swine influenza viruses in July 2020.

Actions:

ECDC is monitoring zoonotic influenza events through its epidemic intelligence activities in collaboration with
disease experts to identify potential significant changes in the epidemiology of the virus. Human cases of zoonotic
influenza should be reported immediately to EWRS and IHR.

Last time this event was included in the Weekly CDTR: –