Study shows fatal spread of H5N1 from ferrets to suckling kits

Sub: Sci

Sec: Health

Context:

Researchers have found that lactating ferrets with mammary gland infection with the H5N1 influenza virus (2.3.4.4b clade) are capable of spreading it to pups.
The virus was previously considered unlikely to spread among mammals, but recent outbreaks in marine mammals and cattle challenge this assumption, highlighting the potential for interspecies transmission.

About H5N1 virus:

H5N1 is a highly pathogenic avian influenza virus that primarily infects birds. The virus can also infect mammals (including humans) that have been exposed to infected birds
The H5N1 virus is primarily spread among birds, especially wild and migratory birds, through direct contact with infected faeces or respiratory secretions.

Spread of H5N1 influenza virus (2.3.4.4b clade):

The highly pathogenic avian influenza A(H5N1) virus of clade 2.3.4.4b, which emerged in 2020, has spread across Africa, Asia, Europe, and the Americas, causing widespread mortality in seabirds, marine mammals, and more recently, farm animals.
By 2023, the virus infected and killed thousands of sea lions and other marine mammals in South America. It also spread to cattle in the U.S. in March 2024, with farm workers becoming infected shortly after.
As of November 2024, 58 human cases and significant outbreaks in dairy herds have been reported.

Infection in cows:

The H5N1 virus of clade 2.3.4.4b infects the mammary glands of cows, with high levels of viral RNA and infectious virus detected in milk. This raises concerns about the potential for milk to act as a medium for virus transmission to offspring and humans.

Research on H5N1 Transmission in Ferrets

Researchers used lactating ferrets to study the transmission of H5N1 (clade 2.3.4.4b) via milk.
The researchers found that lactating ferrets with mammary gland infection with the H5N1 influenza virus (2.3.4.4b clade) are capable of spreading and causing disease in suckling ferret pups.
The study found that ferrets directly infected through milk had 100% mortality, but the virus did not spread efficiently through respiratory droplets.

Human Cases:

The virus has spread to humans in rare cases, especially among individuals with direct contact with infected animals. The first case in a U.S. farm worker was reported in 2023, following exposure to infected cattle.
This raises concerns about the zoonotic potential of the virus and the risk of a broader human outbreak.