The worker of a poultry farm in Castilla-La Mancha has tested positive for avian influenza type H5. This is the first case detected in Spain and the second in Europe, after UK will find another in December 2021. The case was confirmed last Tuesday, September 27, and declared to the European Center for Disease Prevention and Control (ECDC), the WHO and the Center for Coordination of Alerts and Emergencies (CCAES) of the Ministry of Health. The infected remains asymptomatic and has already tested negative, like the rest of the personnel analyzed, that he is taking the antiviral against the flu oseltamivir preventively.
The story goes back to September 12, when the Ministry of Agriculture, Fisheries and Food reported an outbreak of bird flu Highly pathogenic H5N1 in a laying hen farm in the municipality of Fontanar (Guadalajara). It was the 35th outbreak in Spain in 2022. A week later, on September 20, a second outbreak was reported in a farm in Guadalajara, 3 kilometers from the previous one.
Sources related to the case clarify to elDiario.es that the situation “is not worrying” and that it is a positive detected during the active surveillance tasks that are carried out routinely in these places. So far, only hemagglutinin (H5), one of the two proteins on the surface of the virus, has been confirmed, along with neuraminidase (N), which are used to classify them. However, pending definitive confirmation, the existence of an outbreak of the H5N1 subtype on the farm leaves little room for doubt. The sample that was positive was taken on September 23 and the result was confirmed on the 27th. The affected person remained in home isolation until the 28th, when it was negative, according to documents to which elDiario.es has had access.
Health sources clarify that the worker tested positive “with a very low viral load” and that he never developed symptoms. These circumstances have led to inform the health authorities, but without launching an alert.
Up to 60% lethality in humans
Influenzavirus A subtype H5N1 of high pathogenicity is an old acquaintance of the poultry industry and veterinarians due to the high mortality it causes among birds and the enormous economic losses caused by the sacrifices made to control outbreaks. It is also in all the pools of possible more serious future pandemics: although contagion between people is, to date, anecdotal, the high fatality rate in humans, up to 60% according to the WHOworries about the possibility that the virus mutates to be transmitted between human beings.
The H5N1 flu was first detected in the late 1990s in China, and came to the attention of researchers when a 1997 outbreak in Hong Kong confirmed that humans could and seriously spread it: of the 18 recorded cases, 6 they passed away Throughout the 21st century, cases in people have continued to increase: according to the WHO, between 2003 and March 31, 864 cases were registered, of which 456 died, with a fatality rate of 52%.
The current strain was detected in 2021 and since then three cases have been registered in humans: those in Spain and the United Kingdom are joined by another detected in the United States in April.
The largest outbreaks observed in Europe
Although the detection of a case in Spain is not cause for alarm, experts have not overlooked the increase in cases of H5N1 flu in recent years, both in birds and in people, especially since 2020. Precisely this Monday the European Food Safety Authority (EFSA), the ECDC and the reference laboratory of the European Union (EU) shared updated data on these outbreaks.
“The 2021-2022 highly pathogenic avian influenza season is the largest observed in Europe to date,” the ECDC concluded. According to these data, a total of 2,467 outbreaks have been detected in poultry and some 48 million birds have been slaughtered in the affected centers. Detections have also been made in 187 captive animals and 3,573 events were found in wild specimens. “The geographical extent of the outbreak is unprecedented and affects 37 European countries,” the report added.
The new report, already out of date, highlighted that no cases had been observed in humans among the member states. “The general risk to the population remains at a low level, but is slightly higher for people who work in direct contact with infected birds.” For this reason, he insisted on the need for surveillance and prevention tasks such as those that have allowed the Spanish case to be detected.
Bird flu cases have increased tremendously since 2020, both H5N1 and other subtypes such as H5N6 and H5N8. At the end of 2021 the World Organization for Animal Health warned of the need to increase surveillance tasks due to the increase in the intensity of outbreaks among birds. According to their data, 14 million cases detected in 2021 is a record which is better than the previous five years combined. This represented a 462% increase in the number of cases and a 150% increase in the number of deaths compared to the previous year.