Ursula Höfle

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.

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.

Analysis of the two asymptomatic cases of H5N1 avian influenza detected in Spain in autumn 2022 in workers at a poultry farm in Guadalajara has confirmed the theory that no actual infections occurred, but that both were in contact with genetic material of the virus found in the environment. Spain has recently modified its protocols, according to the analysis published in Eurosurveillance.

Outbreaks of highly pathogenic H5N1 avian influenza have been increasing since 2021, but in recent months have evolved into what is known as a 'global panzootic' affecting all types of wild birds and new continents, but also mammals such as mink and sea lions. At a briefing organised by SMC Germany, in collaboration with SMC UK and SMC Spain, three experts discussed the situation, the level of risk and possible next steps.

The H5N1 virus that is causing an unprecedented epidemic among wild and domestic birds has a very low capacity to infect humans. The three cases where infection has been found have been due to close contact with dust raised during the handling of affected poultry.