Increase the spread ofbird flu Also in Italy. Therefore, the circulation of the H5N1 avian flu virus among wild birds increases, with the risk that they may transmit the virus to poultry farms. It emerges from the data of National and European reference center for avian flu at the Istituto Zooprofilattico Sperimentale delle Venezie (IZSVe). The Ministry of Health issued a note a few days ago in which it recognizes the need, says the IZSVe, to strengthen surveillance of wild birds and the application of biosecurity measures in poultry farms.
With increasing cases in wild birds, attention is also growing towards mammals. After the spillover events – i.e. jump of species – in fact, in farmed mink the attention of the health authorities is growing towards mutations of the H5N1 virus that could favor its passage to mammals and humansemphasizes the IZSVe.
The evolution of the global bird flu situation in recent months has raised some concern among the international scientific community. After the confirmed cases of highly pathogenic H5N1 virus (HPAI) transmission from birds in some species of mammals, the World Health Organization (WHO) and the World Organization for Animal Health (Woah) have invited all countries to raise the alert level on the arrival of a new influenza pandemic in the human population supported by a virus of avian origin.
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Because it raises the attention
After the spillover events in farmed mink, the attention of the health authorities is growing towards mutations of the H5N1 virus that could favor its passage to mammals and humans. It is the warning on which the zooprophylactic institute invites you to pay close attention. But why? What risks are there?
“The spread of ceppo H5N1 HPAI among wild birds it is on the increase, in Italy as in the rest of the world – he declares Calogero Terreginodirector of the Avian Influenza Reference Center – In our country, cases of H5N1 HPAI in avifauna mainly concern Veneto, Lombardy, Emilia Romagna and Friuli Venezia Giulia. The Ministry of Health has highlighted how this situation constitutes a constant risk for domestic poultry farms, considering that some areas with a high density of poultry coincide with the areas where cases of HPAI are currently detected in wild animals. As a reference center we are monitoring the evolution of the epidemic throughout the country very carefully, to avoid a situation like in winter 2021-2022».
The situation in Italy
In wild birds starting from September 2022 have been officially confirmed 79 cases of positivity among gulls (19), teals (13), mallards (10) and in other specimens of birds of prey and ducks. Many other suspected cases in seagulls are being confirmed at the IZSVe. The persistence of cases in wild animals highlights the continuous circulation of H5N1 on the Italian territory in line with what is happening in other European and non-European countries where there is an increase in cases also in poultry and wild mammals, and in which cases have been reported even sporadic cases in domestic mammals.
In domestic birds the situation is more favorable, after the dramatic epidemic wave of H5N1 HPAI which mainly affected them the north-east in the winter of 2021-2022, with 317 outbreaks on farms. The latest outbreak in poultry dates back to 23 December 2022, bringing the number of confirmed cases since September 2022 to 30. The outbreaks were mainly found in Veneto, Lombardy and Emilia Romagna.
«The situation in the farms has improved compared to a year ago – says Terregino – thanks also to the intense work carried out by the Ministry of Health in collaboration with the Regions and Local Health Authorities involved, the National Reference Center for Avian Influenza and the representatives of the productive world. The collaboration between the parties has made it possible to address and improve the main critical issues encountered, in particular by strengthening surveillance in wild birds and making prevention strategies and management of outbreaks on farms more effective”.
The risk of transmission in mammals
No cases have been recorded in Italy among mammals, however monitoring activities are also planned for these species, in particular in wetlands frequented by potentially infected wild birds.
The H5N1 virus, like many other respiratory viruses, is very plastic and its genetic mutation rate is quite high. Some strains of the H5N1 virus currently circulating among birds have shown mutations considered signs of adaptation to mammals. Some animals, such as mink, may allow for the genetic reassortment of different influenza viruses, from which they can emerge viral variants most dangerous for animals and humans. Studies are currently underway in the laboratories of the IZSVe reference center for avian influenza to investigate the genetic and biological characteristics of the strain identified in mink in Spain.
Genetic surveillance allows not only to correctly identify the virus but also to study its mutations. The studies conducted so far by the IZSVe indicate only a partial evolution of the virus which, for the moment, is not capable of causing human-to-human contagion. However, it cannot be excluded that the virus in the future may acquire characteristics such as to make it transmissible from man to man. One of the most effective weapons for promptly identifying this eventuality is the sharing of genetic sequences among members of the scientific community, in order to follow the evolution of the virus in time and space and understand if mutations that favor replication in mammals occur.
The risks for humans
Although primarily affecting poultry and wild birds, avian influenza can occasionally be transmitted to mammals, including humans. Since its emergence in 1996 on a goose farm in China, the H5N1 virus has also caused cases of infection among humans in various countries of the world, but with sporadic frequency and in particular conditions. To date, no cases of human-to-human transmission of the H5N1 virus have been reported.
Avian viruses are not able to infect humans easilyin most cases H5N1 infections occurred in people in close contact with infected birds in very poor areas, in conditions of strong promiscuity and poor hygiene, without adequate awareness of the presence of the disease and the risks associated with it. There are professional categories more exposed to risk, such as poultry farmers, veterinarians, slaughterers, transporters. For these subjects, who could come into contact more frequently with birds infected or dead from avian flu, health monitoring is envisaged in the event of an epidemic and vaccination against human flu is recommended, as a measure to prevent phenomena of genetic recombination between human seasonal virus and bird flu virus.
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