Will bird flu be the next pandemic? “It is highly possible” according to Arnaldo Caruso, president of the Italian Society of Virology (Siv-Isv), who in an interview with Adnkronos Salute does not mince words on the fears raised by the epidemic growing among dairy cattle in the USA , due to a highly pathogenic strain of H5N1 virus also found in fragments in pasteurized milk sold overseas. In the scientific community “there is great concern”, explains the expert who has just returned from Barcelona, where he participated in the Congress of the European Society of Clinical Microbiology and Infectious Diseases (Escmid). “The passage of avian flu into mammals and the circulation in these animals – he warns – is a step forward towards humans”.
The specialist, full professor of microbiology and clinical microbiology at the University of Brescia and director of the Microbiology Laboratory of the Asst Spedali Civili, paints a “perhaps pessimistic picture – he admits – but unfortunately we must not put our heads in the sand. Instead we must be realistic and prepare”, warns Caruso. Thinking about a future pandemic emergency, he underlines, “the avian virus is the only one that is really worrying” 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”. The pathogen, then, is extremely widespread: “Wild ducks are carrying it everywhere, which we now also see in our cities, in our ponds, in our waterways”. And it is changing: “Not only H5N1 – specifies the expert – but various strains of avian virus are modifying themselves, at the level of multiple surface receptors, in order to adapt to humans. An increasingly easier leap, after passed to mammals and circulates among mammals.”
We are therefore faced with “not one avian flu, but several avian flus – Caruso points out – which have entered the mammal and are all potentially dangerous for humans. They are worrying because the circulation in mammals indicates that the virus is evolving into a clear direction: it has taken a path which inevitably, sooner or later – the president of Italian virologists suggests – will lead to its arrival in humans who will be able to become its reservoir and spreader”.
How the transmission of the virus will change
Will we lead to human-to-human transmission of the avian influenza virus? “It is inevitable – replies Caruso – that when the virus enters humans again and again, it will be able to take on that ‘fitness’, that is, that ability to adapt to human cells, which will allow humans to act as a reservoir and therefore as a diffuser for other men”.
Beyond the cases known for exposure, professional or otherwise, to infected animals, “who knows how many times humans have already been infected, perhaps without presenting important symptoms – reasons the Siv-Isv president – Who knows how many avian viruses are trying to enter in man and how many times they succeeded.” Therefore, if it is true that to date human-human contagion has never been confirmed for the avian virus, “it does not mean that human-human transmission is not already possible – observes Caruso – or that at least some strains have not already been stabilized in humans”.
In short, “the situation is truly worrying – is the message – and requires stringent surveillance of animals, not just birds, of foods of animal origin consumed by humans and of humans themselves. It is essential to be ready, prepared for a new possible future pandemic”.
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Avian flu, ECDC: “Risk of large-scale transmission if the virus mutates”
“Indispensable surveillance”
“Strong, very careful and very prompt surveillance is essential” against the avian flu which is spreading among dairy cattle in the USA and which the scientific community is viewing with fear due to the “strong” possibility that it could cause the next pandemic. “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, on humans too.” Above all, “we need to quickly prepare vaccines that can be administered when necessary. Not only vaccines aimed at the H5N1 virus, but also at other strains that are moving to mammals”. This is the appeal launched by Arnaldo Caruso, president of the Italian Society of Virology (Siv-Isv), in an interview with Adnkronos Salute.
“The avian virus is a pathogen that evolves easily and is mutating in order to adapt not only to mammals, a leap that has already taken place, but also potentially to humans”, underlines the expert, full professor of microbiology and clinical microbiology at the university of Brescia and director of the microbiology laboratory of the Asst Spedali Civili. Threatening humans “there are multiple avian strains – he specifies – and we don’t know which variant will be able to take hold to the point of one day becoming established and circulating in humans. H5N1 would seem to be the most probable, but there are also others pay attention and vaccines will have to be ready for these too, if necessary. Let us be ready to avoid trouble”, warns Caruso.
“Today we control poultry farms and other birds at risk of avian flu, and we ensure the elimination of all infected or potentially infected specimens”, recalls the number one Italian virologist. But as the epidemic among US cattle shows, “the infection can also stabilize in mammals, in animals on which avian flu checks are not yet carried out because there was no need”. The invitation is therefore to extend surveillance to other animals, as well as “to the foods derived from them in order to ascertain their healthiness”. After the discovery of highly pathogenic H5N1 fragments in samples of pasteurized milk on the market overseas, Caruso is keen to point out that it is “extremely unlikely that contagion could occur through food, especially if we are talking about pasteurized milk or cooked meat. But surveillance it is fundamental – he insists – considering the circulation in animals that provide milk and meat”.
“Even before the passage of viral circulation from mammals to humans, foods must therefore be controlled” as part of surveillance that needs to be strengthened. But for the specialist “from now on, surveillance in humans is also very important: we must understand how much avian flu is circulating in the world, even at a sub-clinical level, with insignificant symptoms”. Because if the virus were to consistently infect humans, the danger is that it adapts to humans to the point of one day being transmitted from one person to another. “It is not excluded that the virus could already begin to circulate – observes Caruso – that somewhere in the world it has already stabilized in humans. 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 summary, the virologist urges, “we should not only monitor the animals, not only monitor their products which are marketed for food purposes, but also organize a population control network, even random, to understand if the avian virus is already entering and circulating in some enclaves worldwide, or is still waiting to adapt to humans”. 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.”
