The next pandemic could be that ofavian? A strain of a bird flu virus has been spreading among cattle in the United States for months, and scientists have long been warning about the risks this disease could pose to humans.
When asked whether the virus that affects and kills birds could trigger the next one pandemic in menmany virologists respond that it is “strongly possible”.
Data around the world
The alarm was raised in Italy Arnaldo Carusopresident of the Italian Society of Virology (Siv-Isv), who does not mince words in describing the fears raised by the epidemic that is spreading among dairy cattle in the United States.
The epidemic is caused by a highly pathogenic strain of H5N1 virus, which has also been found in pasteurized milk sold in the United States. “The passage of avian flu into mammals and the circulation in these animals – she warns – is a step forward towards humans”.
It is not the first time that the avian alarm has been raised and although at the moment there is no evidence of direct contagion between people, Scientists fear that the avian influenza virus could mutate from cattle to humans, facilitating its spread. From the beginning of 2003 to April 1, 2024, the World Health Organization (WHO) recorded a total of 889 human cases of avian influenza in 23 countries, with 463 deaths, for an alarming mortality rate of 52%. A recent case of infection in Texas, United States, raises questions about the route of transmission, but it is not yet clear whether the man contracted the virus from an infected cattle or a bird. The case involved a company worker commercial dairy that had only mild disease, with appearance of conjunctivitistreated outside the hospital.
In light of the events taking place in America, the European Center for Disease Prevention and Control and the European Food Safety Authority have proposed a series of measures such as strengthening surveillance and sharing of genomic data, as well as careful planning of poultry and fur-bearing farming, especially in areas with high waterfowl densities. Vaccination of animals and people at risk due to their work is also recommended.
The warning from virologists: “We must prepare, mutations are coming”
“We must not put our heads in the sand. Instead, we need to be realistic and prepare.” Thinking about a future pandemic emergency, Caruso underlines how the avian virus is the only one that really worries for more than one reason. First of all because “it is an influenza virus which as such is transmitted by air, the most effective in terms of contagion”. And also because the pathogen is extremely widespread given that it has been discovered that it is present in many wild ducks, such as those we see in our cities.
But another alarming fact is that the virus is mutating. “Several strains of avian viruses are modifying themselves, at the level of multiple surface receptors, in order to adapt to humans. An increasingly easier leap, after it has passed to mammals and it circulates among mammals.” There is therefore not just one avian flu as there was years ago, but different types of influences that are entering mammalian organisms and which are all potentially dangerous for humans.
According to the guidelines of the Ministry of Health, gastrointestinal symptoms such as nausea, vomiting and diarrhea have been reported more frequently in A(H5N1) infection. Also there conjunctivitis has been reported in some cases. In many patients with avian influenza virus, the disease has an aggressive clinical course. The initial ones are the common flu ones, like high fever (greater than or equal to 38°C) and cough followed by symptoms involving the lower respiratory tract, including wheezing or difficulty breathing. Upper respiratory symptoms such as sore throat or cold are less common.
What can we do to counter the risk of a new pandemic
For Caruso, rigorous and prompt surveillance is essential to combat avian influenza, which is spreading among dairy cattle in the United States. “Not only birds need to be monitored, as has already been done for some time, but also other animals and the foods derived from them, from milk to meat. And we need to start carrying out checks, perhaps on a random basis, also on humans.”
Furthermore, it highlights the urgency of rapidly develop vaccines that can be administered if necessary. Not only vaccines aimed at the H5N1 virus, but also at other strains that are spreading among mammals. Caruso is keen to point out that it is “extremely unlikely that contagion can occur through food, especially if we are talking about pasteurized milk or cooked meat. But surveillance is essential, given the circulation in animals that provide milk and meat.”
It is therefore important strengthen surveillance and carry out checks to understand the extent of circulation of the avian virus, even at a sub-clinical level. This is because, before the virus adapts to humans and becomes capable of transmitting from person to person, it is essential to understand how widespread it is. To date, all this is not being done: “It is not excluded that the virus could already begin to circulate, that somewhere in the world it has already stabilized in man. We cannot know because we are not carrying out surveillance, but now this surveillance is necessary, to avoid finding ourselves unprepared for a possible next pandemic”.
In short, the virologist urges the implementation of complete surveillance that includes not only animals and their products intended for food, but also a monitoring of the human population to identify any foci of circulation of the avian virus. A control network that should be organized randomly to understand if the virus is already spreading in certain enclaves globally or if it is still limited to animals.
Finally, as regards objects and surfaces, “we know that the virus cannot survive there – reassures Caruso – If exposed to air, in fact, the covering that covers it tends to dry out and the pathogen is no longer able to infect target cells. It is also very sensitive to soaps and detergents.”
