The bird flu virus currently causing outbreaks in birds and cattle in the US can be transmitted to humans through our cats.

If the virus adapts to move quickly among our furry friends, it could also spread more easily from cats to humans, according to a new paper in the journal Emerging Microbes & Infections.

Virus A(H5N1) or “bird flu H5N1” is a highly pathogenic strain of influenza A virus that primarily infects birds, especially poultry. It can occasionally be transmitted to humans and other animals.

A recent outbreak of clade 2.3.4.4.b affected 832 cattle herds in 16 states, CDC data show, with 10,718 wild birds and 122,790,926 poultry affected nationwide.

There have also been a total of 58 human cases of H5N1 bird flu in the US, with 32 people infected in California and other cases in Colorado, Michigan, Missouri, Oregon, Texas and Washington. All but one of the California cases were caused by livestock exposure.

An outbreak of H5N1 also occurred in South Dakota in April 2024, resulting in the death of 10 cats after they showed neurological and respiratory symptoms, according to the new study.

Cats have been previously infected with H5N1 but have tended to have only respiratory symptoms. This 2.3.4.4.b clade also appears to result in neurological effects that have also been observed in sea lions and foxes.

According to the article, cats can contract H5N1 from birds or cattle and serve as a reservoir for human infection. The virus in South Dakota cats was also found to have mutations unique to cats, meaning the virus is able to adapt to new hosts.

“We identified several key mutations in the H5N1 sequence from infected cats that may indicate adaptation to cats,” the researchers wrote.

This means the virus could adapt to better infect humans, potentially jumping from cats to humans for the first time.

“Infected cats develop systemic infections and virus is shed through both the respiratory and digestive tracts, potentially creating multiple routes of exposure for humans. In addition, the ability of the virus to persist and adapt in mammalian hosts increases the risk that they will evolve into strains with increased portability.” , representing an emerging zoonotic threat with profound public health implications,” the researchers wrote.

“As H5N1 viruses continue to infect a wide range of avian and mammalian hosts, including an increasing number of human cases, there is an urgent need for coordinated One Health surveillance to track the spread of H5N1 among domestic and wild birds, animals and humans. .”

Reference

Chothe, SK, Srinivas, S., Misra, S., Nallipogu, NC, Gilbride, E., LaBella, L., Mukherjee, S., Gauthier, CH, Pecoraro, HL, Webb, BT, Pipas, JM, Ramasamy, , S., & Kuchipudi, S. V. (2024). Prominent neurotropism and potential adaptation of H5N1 clade 2.3.4.4.bu virus from naturally infected domestic cats. Emerging microbes and infections. https://doi.org/10.1080/22221751.2024.2440498