A case of swine flu in a man in Lleida is being investigated, the first case outside of a farm.

BarcelonaThe Catalan Health Department confirmed a human case of swine flu A (H1N1) in Lleida, which was identified on February 11. The patient, an elderly man with chronic illnesses, had gone to the hospital on January 30 for a routine check-up. Although he did not present with flu-like respiratory symptoms, a nasal swab was taken as part of epidemiological surveillance testing for influenza viruses, and the positive result was identified accidentally. The patient is doing well and has already recovered, according to the Health Department, and no further cases have been detected so far, not even among close contacts, who were tested. Currently, the situation is considered under control, but the source of the infection will remain under investigation. Swine flu viruses circulate widely among livestock, but transmission to humans occurs sporadically. In fact, this is the first case of swine flu detected outside of a farm in Catalonia in the last seventeen years. In 2023, a in a worker in the sector. The regional health department points out that this is not the case: neither the affected individual nor their immediate circle has any contact with pigs or farms, so health authorities are investigating the source of the infection.

The regional health department emphasizes that the risk of infection with this virus is "very low" for the general population and "low" for people who work with these animals. However, when infection does occur, it mostly causes mild respiratory infections, although more severe cases have occasionally been identified. According to the health department, the case was officially reported to the Center for Coordination of Health Alerts and Emergencies (CCAES) on February 13, which in turn forwarded it to the World Health Organization (WHO) reference center. All of this is in compliance with the International Health Regulations, which require authorities to report any case of this flu detected in humans.

In this regard, the Catalan Health Department (Salut) has announced in a statement the opening of a "full investigation" and the activation of epidemiological surveillance, microbiology, and institutional communication protocols. This is the fourth reported infection of this virus in humans in Spain since 2009, the year of the flu pandemic that began in Mexico and the United States and spread globally. The last case was also identified in Catalonia, in December 2023, on a farm in Lleida. Experts consider it unlikely that this virus is transmitted from pigs to humans and between humans, but also that many cases probably go undetected because not enough epidemiological surveillance tests are performed or because they are asymptomatic.

Risk factors and possible origin

According to the WHO, swine flu is not transmitted through food, so the risk of contracting the virus from consuming pork products is "negligible," even during the acute phase of the infection. Direct human exposure to pigs is the most common risk factor for infection, especially when there is direct, unprotected contact with infected animals. In this case, neither the person treated nor their direct contacts had prior exposure to pigs or pig farms, nor to other potential animal carriers. "All the people studied were asymptomatic, and the tests came back negative. Furthermore, possible errors or contamination in the sample collection have been ruled out," the Catalan Health Department (Salut) stated. In this regard, the authorities are investigating two possibilities: either a one-off case of asymptomatic flu or that the patient was not infected, but that, for some reason, there was environmental contamination. "Right now, we think it's possible environmental contamination that may have resulted in a positive laboratory test," stated Jacobo Mendioroz, Deputy Director General of Public Health Surveillance, as the leading hypothesis. Blood samples have now been sent to the reference laboratory in Madrid and to the WHO laboratory to determine whether the affected person had contracted the virus or was an asymptomatic carrier (environmental contamination). The Respiratory Virus and Influenza Reference Laboratory at the National Microbiology Center of the Carlos III Health Institute will also analyze the serum to confirm or rule out a possible infection. If antibodies against the disease are detected, then the person would have actually been infected.