Will bird flu mutate and spread to humans? Experts are concerned.

In recent days, health alarms have been raised in Andalusia due to a significant increase in avian flu outbreaks in various parts of the region. Cities such as Malaga and Seville have seen dozens of birds die in iconic parks, leading local governments to close public spaces as a precautionary measure. Furthermore, another outbreak of H5N1 avian flu has been detected in Doñana , prompting preventive protocols, including increased surveillance and the safe removal of dead birds.

Although all eyes are on these hotspots, the truth is that the story goes back a long way and should not be ignored, as Joaquim Segalés , professor at the Faculty of Veterinary Medicine at the Autonomous University of Barcelona, ​​explains to this newspaper: “Highly pathogenic avian influenza (HPAI) caused by the influenza A virus subtype H5N1 represents a continuous threat to global animal health and, increasingly , to public health. In fact, a panzootic, the equivalent of a pandemic but in animals, of HPAI H5N1 influenza viruses in wild birds is considered to have occurred since 2019-20, and that this has led to major outbreaks in domestic birds.”

In this regard, the researcher at the Animal Health Research Center of the Institute of Agrifood Research and Technology points out that we must not overlook the risk that exists due to "the fact that cases in domestic birds bring the virus closer to people , although it is considered low by the World Health Organization."

Regarding the new outbreaks detected in Spain, Dr. Patricia Guillem Saiz points out that there is indeed a risk to human health , "but with nuances." She also conveys reassurance that the WHO has classified the risk of contagion as "low" and points out that human cases have been rare and linked to people in "direct exposure to infected birds (alive or dead), especially poultry workers." However, she emphasizes that "among the documented cases, some presented mild symptoms and others, however, more severe. In 2023 and 2024, human infections were documented in several countries, even reaching the United States , China, and Cambodia."

The risk of virus mutation

In any case, Dr. Guillem warns that "the real fear is that the virus will mutate, allowing it to transmit efficiently between humans ." " If this happens , it could cause a new pandemic," says the professor from the Department of Preventive Medicine and Public Health at the University of Valencia.

A risk that the professor also considers : “The increasing appearance of the H5N1 virus in mammals , including dairy cattle and domestic animals, increases the risk of genetic reassociations and mutations with pandemic potential in humans.” “In the event of the virus adapting to efficient replication in mammals, the possibility of generating variants with a higher transmission capacity is not negligible and that is why we must strengthen both passive and active health surveillance systems, as well as monitor infections and strictly track viral evolution,” he adds.

The expert from the University of Valencia explains that "there is concern due to the mutagenic possibilities presented by the virus ," which has already been seen in transmission between mammals (mink, seals, cats, etc.), "which indicates that the virus is adapting and how H5N1 (a similar strain) acts by acquiring the capacity for sustained transmission between humans , which could lead us to face a serious pandemic again."

He insists that the risk is posed because although in principle "it's a virus that should only be transmitted between birds, it has been shown to have already been transmitted to other animal species and also to humans ." "And when a virus changes organisms or species, it can mutate, and that not only affects its ability to infect and transmit from one organism to another, but these mutations can also affect its pathogenicity . So, it's not only important that it be transmitted, but also if the strain in which it mutates becomes more virulent," he explains.

In this sense, he emphasizes that Zoonosis “could be silent, with the risk of people becoming infected in a mild or asymptomatic manner, which would make early detection difficult if the virus began to spread.”

She also emphasizes that "it is necessary to focus on the concept of One Health and for different healthcare professionals to join forces to seek answers and work toward common research goals ." The expert adds that "pandemic fatigue and low investment in epidemiological surveillance can hinder an effective response."

When asked about how to proceed to stop the outbreaks we are experiencing in Spain, the veterinary professor explains that the spread of the virus has been facilitated by the migration of wild birds and the structure of industrial and backyard poultry farming in several regions of the world. "While the rapid elimination of outbreaks through stamping out has been effective in specific contexts (such as in some European countries), this strategy is not always viable in regions where the virus is endemic, and in these areas, vaccination is advocated as a complementary tool to mitigate the disease. In both situations, biosecurity is a fundamental tool to try to reduce transmission from wild to domestic birds," he explains.

In addition to animal protection, the Valencian doctor adds that of humans , which "is fundamental." She believes that protective equipment must be available for poultry workers and veterinarians; direct contact with sick or dead birds must be avoided ; educational campaigns must be conducted in rural and agricultural areas; suspected cases in humans must be monitored; and preventive human vaccines must be researched and developed.

It also notes that "since this is an international public health issue," it requires close collaboration between the WHO, FAO, and OIE "to ensure monitoring and respond to early warnings , and sharing genetic information about the virus would aid in the development of vaccines and antivirals."