In October 2024, the United States CDC reported a third human case of H5 bird flu in the state of California. This announcement followed the identification of two human cases just a week before. All three cases have reported occupational exposure to infected dairy cows, but none has been hospitalised. The CDC risk assessment for the public remains “low”.
Three cases reported
The first two human cases were reported on 3rd October 2024 in people with occupational exposure to infected dairy cows. H5N1 outbreaks in dairy herds were first reported in California in August 2024. The cases had no known link or contact, indicating separate instances of animal-to-human spread. Sequences from these cases confirmed clade 2.3.4.4b A(H5N1) viruses, closely related to viruses detected in dairy cattle. Whole genome sequencing from one of the cases confirmed a B3.13 genotype virus.
“There were no genetic changes observed that are known to be associated with an increased ability to infect or spread between people or known to reduce susceptibility to antiviral medications.”
The third case, reported on 9th October 2024, also reported occupational exposure and no known contact with the other cases. Sequencing of this case is underway. The infected people experienced “mild” symptoms, including conjunctivitis. None of the three cases has been hospitalised.
The broader risk
CDC’s risk assessment for the general public is still “low”. This case takes to total human cases of H5 bird flu to 17 in 2024. Cases have been reported in Texas (1), Michigan (2), Colorado (10), Missouri (1), and California (3). Only one case, in Missouri, has not had source confirmation. The agency emphasises the importance of recommended precautions for people with exposure to infected or potentially infected animals.
At the Congress in Barcelona this month we will explore avian influenza during the One Health and Veterinary track, considering the role of vaccination in One Health strategies and learning from our experts’ experiences. Get your tickets to join us there and don’t forget to subscribe to our weekly newsletters for more health news.
