By Leah Douglas and Tom Polansek, Reuters
A digitally-colorized microscopic image of Avian Influenza A (H5N1) virus particles (seen in gold), grown in epithelial cells (green). Photo: CDC/ Cynthia Goldsmith, Jacqueline Katz, Sherif R Zaki
The US has reported its first severe human case of bird flu in a Louisiana resident who is hospitalised in critical condition after suspected contact with an infected backyard flock.
The illness shows increased risks from the virus that previously caused eye redness, or conjunctivitis, in infected farm workers.
H5N1 bird flu still represents a low risk to the general public, the US Centres for Disease Control and Prevention said.
CDC has confirmed 61 human cases since April, mostly in workers on dairy farms where the virus infected cattle. Workers culling infected poultry have also tested positive.
The patient in Louisiana is in critical condition and suffering severe respiratory illness, the Louisiana Department of Health said in a statement. The person is reported to have underlying medical conditions and is over the age of 65, the department said, putting the patient at higher risk.
The case is the first to be linked to backyard, non-commercial poultry, said Demetre Daskalakis, director of CDC's National Centre for Immunisation and Respiratory Diseases, on a call with reporters.
The CDC said a sporadic case of severe illness in a person with H5N1 bird flu is not unexpected as such cases have occurred in other countries in 2024 and prior years, including cases that led to death.
"The mild cases that we've seen in the United States largely reflect that many of the individuals are getting infected by dairy cows and that's very different than getting infected with infected birds," said Amesh Adalja, a senior scholar at Johns Hopkins Centre for Health Security.
"If you look at the genotype of this patient in Louisiana, it wasn't the cattle strain. It was a wild bird strain."
CDC said partial viral genome data from the infected patient shows that the virus belongs to the D1.1 genotype, recently detected in wild birds and poultry in the United States and in recent human cases in British Columbia, Canada, and Washington state.
This genotype of the virus is different from the B3.13 genotype detected in dairy cows, human cases in multiple states, and some poultry outbreaks in the country, CDC said.
Bird flu has infected more than 860 dairy herds in 16 states since March and killed 123 million poultry since the outbreak began in 2022.
There has not been evidence of dairy herds being reinfected once they have cleared the virus, said US Department of Agriculture deputy under secretary Eric Deeble on the press call. The agency has enrolled 13 states in its newly launched national bulk milk bird flu testing plan, representing nearly half of the nation's milk supply, Deeble said.
-Reuters
