New zoonotic alert?Changes in bird flu virus may increase risk of transmission to humans

according to World Health Organization (WHO), “this Avian influenza, also known as bird flu, Is a infectious disease This mainly affects birds and is caused by a Orthomyxoviridae.According to its subtype, it can be divided into “Low pathogenicity anyone highly pathogenicpresent different symptoms in infected birds.

For the World Health Organization, “the most common way a virus enters an area is through migratory birds; while the “main Risk factors for transmission from birds to humans It’s him direct or indirect contact Contact with infected animals or fecal-contaminated environments and surfaces”.

Meanwhile, according to the agency, “the emergence of causative infectious diseases over the past two decades and more recently Zoonotic Outbreaks There is growing public concern about the fact that diseases spread between species. ” In this regard, a survey found that A subtype of avian influenza virus trying changes in its composition,what can I do Increased risk of disease transmission to humans.

Currently, there are outbreaks in different parts of the world.For example, in Argentinaaccording to the latest results Analysis of samples from the National Agricultural Products Health and Quality Service (Senasa) from dead animals The Puerto Madryn (Chubut) and Sierra Grande (Rio Negro) coasts in the rest of the country are the focus of the avian influenza outbreak. However, to date, no human cases associated with these outbreaks have been reported.

In this sense, the recent scientific research Research conducted by researchers from China and the UK proposes Avian Influenza Virus Subtype dominant is Chinese poultry farm trying Changes that increase the risk of the disease becoming zoonotic.

The experts published their findings in the journal cell, affiliated with the University of Nottingham, China Agricultural University in Beijing, the Chinese Academy of Sciences and the Chinese Center for Disease Control and Prevention. In their work, they entered the virus subtypes analyzed.

“An H3N8 avian influenza virus (AIV) in China caused two confirmed cases of human infection in 2022, followed by a reported death in 2023. The H3N8 virus circulates widely in chicken flocks; however, zoonotic features It is unclear. Here we demonstrate that they can efficiently infect and replicate in normal organotypic human bronchial and lung epithelial cells.”

Study using laboratory mice and ferrets as models of human infection finds the virus undergoes several infections adaptive change. These modifications allow it to cause serious infections in animals and to spread from animal to animal through the air.

In this spirit, one of the study’s authors, Professor Kin-Chow Chang of the University of Nottingham, describes: “We found that avian H3N8 viruses isolated from patients with severe pneumonia could replicate efficiently in bronchial and lung epithelial cells. In humans, it has extremely deleterious effects on mammalian laboratory hosts and can be transmitted by respiratory droplets.

Second, Kin-Chow Chang hypothesizes: “It is noteworthy that we find The virus has acquired a binding preference for human receptors and substitution of amino acids required for airborne transmission. Even with vaccination against human H3N2 viruses (another subvariant), human populations appear immunologically naive to emerging mammalian-adapted H3N8 viruses and may be susceptible to epidemic or pandemic infection. “

In humans, avian H3N8 virus infection has been shown to cause symptoms such as acute respiratory distress, which can be fatal in some cases, according to the authors.

“Influenza virus resistance to acid is also an important hurdle that avian influenza viruses must overcome to gain adaptation and transmissibility in new mammals or humans, which is what we investigated in this work. The current H3N8 viruses have not yet acquired acid resistance. Therefore, we should pay attention to changes in acid resistance of new H3N8 viruses,” said another author, Professor Liu Jinhua of China Agricultural University in Beijing.

There are more than 200,000 South American sea lions on the Atlantic coast of Argentina, or South American sea lions usually gather in groups. Since August, these animals have suffered greatly from infection with the highly pathogenic avian influenza virus.

So far, 13 coastal towns from Buenos Aires to Tierra del Fuego have confirmed cases of bird flu in wolves. In any case, Argentine sea lions are not the only ones suffering from the outbreak. They belong to the species Otaria flavescens, which also inhabits the coasts of Peru and Chile; the pathogen also killed more than 3,500 specimens in those countries last summer.

At the same time, it should be borne in mind that during 2022 and mainly 2023, the region of the Americas suffers from avian influenza epidemics associated with the A(H5N1) subtype. From an evolutionary perspective, the prevailing strain belongs to a group called clade 2.3.4.4b, which has similar genetic changes to the group that spread throughout Asia, Africa, Europe, and the Middle East from late 2020 to 2021. At the end of the same year, the virus was also found in North America. The Pan American Health Organization has warned of an “alarming” rate of spread and a high death rate.

Argentina begins to see outbreaks February in the past wild bird They then moved on to research in poultry. As a result, the country lost its bird flu-free status and returned to it in August when the poultry outbreak was brought under control.