Reports and publications

EFSA published its latest report about AI in March 2024. A short abstract of the report is presented: “Human infections with avian influenza remain rare and no sustained human-to-human infection has been observed. The risk of infection with currently circulating avian H5 influenza viruses of clade 2.3.4.4b in Europe remains low for the general population in the EU/EEA. The risk of infection remains low to moderate for those occupationally or otherwise exposed to infected animals.”

Weekly reports of human infections are still available on the website of WHO.

On EFSA's website there is a comprehensive and systematic review about the available vaccines against AI and vaccination strategies and also on the role of mammalian species of in AI. A review was recently published about the reported natural infection of wild mammalian species. Comparison was also drawn between previous (2003-2019) and the most recent (2020-2023) spillovers. However, revision of such publication is soon advisable because of other novel spillover events.

There is a recent study about the efficacy of AI vaccines as well.

A preliminary study about the epidemiology of recent AI infections in the USA thoroughly discussed origin of the virus with several other aspects and concerns.

Wild and farm animals

In January 2024 the first polar bear died in Alaska due to avian influenza infection. Few days later HPAI has been found in elephant and fur seals on the subantarctic island of South Georgia. The infectious source was mostly migratory birds from South America.

In March 2024 a goat was tested positive with HPAI in Minnesota, USA. Since, no additional infected goat was identified. Few days later cats and dairy cows got infected with avian influenza was identified in Texas, USA. Cows showed mild symptoms with decrease in milk production, however the cat, fed by raw milk and colostrum from the infection cows dead. Highlighting caution and avoidance of raw milk consumption to avoid cross-species transmission. However, heat treatment of milk can significantly decrease or eliminate the infectious particles in the product, therefore these type of products are still considered safe. Following the identification of AI in cows several other cases were identified in different states.

Raw milk samples from infected cows also contained HPAI genetic elements. Thus, replication and thereafter shedding is possible in the mammillary gland.

Human and avian influenza virus receptor expression was previously demonstrated, and with that, a potential co-infection could result in virus genom reassortation in this organ. Therefore, cattles are now considered as ‘mixing vessel’ of influenza viruses and posing zoonotic risk.

H7N3 is spreading in poultry flocks in mainland of Australia.

Human cases

The first human cases were also reported in different countries. There was a human case reported in Texas, USA, where the individual got infection after the close contact with a cow presumed to be infected with AI. Australia reported their first H5N1 infection in human after supposed exposure in India where the individual travelled. In Mexico the first human case of H5N2 infection was reported. Sadly, the elderly man with several health issues died.

Pets

Not just humans but house pets, e.g., dogs and cats, can become infected with avian influenza. Infection could result in symptoms ranging from mild, non-specific respiratory and digestive issues to severe and potentially fatal conditions.

Notably, the first Hungarian cat infection was also recently reported.

Still, the general risk of infection with AI to public health, especially in the European general public, remained low. However, constant monitoring, laboratory testing and vigilance is required.