Gustavo del Real

A team in the US has tested the efficacy of baloxavir, an antiviral already on the market for treating common flu, against avian influenza in mice. The results, published in the journal Nature Microbiology, show that it is more effective than the currently recommended oseltamivir (Tamiflu) except when the infection is via the mouth, in which case it is equally effective. According to the authors, baloxavir ‘could be considered for the potential treatment of serious H5N1 virus infections in humans’.

A team of researchers from the USA has analyzed the B lymphocytes of seven healthy people in whom no exposure to H5 influenza viruses, such as the avian flu virus, had been documented. The results show that they present antibodies capable of recognizing this type of virus, which, according to the authors, could represent “a first line of defense” in the event of a pandemic. The results are published in the journal Science Immunology.

A study carried out in China has analyzed tissues from 461 fur animals, mostly farm-raised. They found 125 virus species, 39 of which presented a high risk of interspecies transmission. According to the authors, who publish the results in the journal Nature, “there is a need for more extensive and regular surveillance to assess the public health risks that could result from fur animal farming”.

The H5N1 avian influenza virus can be transmitted between mammals, according to a study published in Nature. The research team isolated the virus from the milk of an infected cow in New Mexico (USA) and found that it spreads in mice and ferrets, reaching the mammary glands of both animals. In addition, the virus was also transmitted from infected lactating mice to their offspring. The European Centre for Disease Prevention and Control (ECDC) has issued a press release on Monday recommending increased surveillance for these viruses.

The European Centre for Disease Prevention and Control (ECDC) reported that on January 29th, Spanish authorities notified a possible case of human infection with swine flu virus A(H1N1)v in a worker from a Catalan pig farm. After being diagnosed with bronchitis, subsequent laboratory analyses confirmed it as swine flu A(H1N1)v. The ECDC informs that the patient has fully recovered, and to date, no new cases have been detected among close contacts or among the worker's colleagues at the farm.

A review examines the role of domestic and semi-domestic animals, such as cats, in the emergence of potential zoonoses due to their close contact with humans. The paper, published in the journal Science Translational Medicine, concludes that companion animal health risks will become increasingly problematic with climate change and rapid urbanisation.

An international group of scientists has studied epidemiological data since 2005 and more than 10,000 viral genomes to conclude that the epicentre of H5 avian influenza has shifted from Asia to parts of Africa and Europe. New lineages have emerged from these regions between 2020 and 2022, which evolved by genetic reassortment with low pathogenic viral variants as they spread. According to the authors, who publish their findings in the journal Nature, the increasing persistence of avian influenza in wild bird populations may be driving the evolution and spread of new strains.

Influenza A can cause influenza in humans, birds, pigs, and other mammals. In 2009 and 2010, a pandemic caused by the pdm09 strain—popularly called 'swine flu' because it contained genetic sequences from avian, swine, and human influenza—caused thousands of human deaths worldwide. Since then, this lineage has crossed over 370 times from humans to pigs in the United States, according to a study published in PLOS Pathogens. The research also indicates that the circulation of the virus among pigs may cause further evolutionary changes in this lineage, which would increase the risk of the virus passing back to humans.

According to a statement issued Monday by the World Health Organisation (WHO), Poland has reported that "unusual" cat deaths have been found in several areas of the country. Of the 47 samples tested (46 from cats and one from a caracal, another type of feline), 29 were positive for the avian influenza A(H5N1) virus. The surveillance period for all contacts has now ended and no contacts have shown symptoms. According to WHO, "sporadic A(H5N1) infections of cats have been reported previously, but this is the first report of a large number of infected cats in a large geographical area within a country".

Although outbreaks of H5N1 avian influenza have reached record numbers in recent years, human infections remain anecdotal. A study published today in Nature identifies a protein responsible for inhibiting the replication of this virus in humans, while 'human' flus are able to evade it. The authors propose that this protein with antiviral activity evolved in primates and consider that resistance or sensitivity to it should be taken into account when assessing the zoonotic potential of avian influenza viruses.