#18,506
It's been just over 2 weeks since our last review (see An Overview of Significant HPAI H5 Related Events Over The Past 4 Weeks) of recent HPAI milestones, and if anything the pace of new developments has quickened.
Over the past 2 weeks:- The number of confirmed H5 human cases in the U.S. has increased by 6, to 64 (although probable cases brings that to 71). Four new states have reported human cases (Delaware - 1, Iowa - 1, Louisiana - 1, Wisconsin-1).
- While most of the H5 infections in the United States have been uncharacteristically mild, last month British Columbia reported a severe case in a teenager, and last week the CDC Confirmed the First Severe Case of H5N1 Bird Flu in the United States.
- The number of known infected dairy herds has grown from 720 to > 875 (a 21% increase), and the USDA has reported well over 10 million head of poultry lost to the virus.
- With half of the state's dairy herds infected, last week the Governor of California Declared a Bird Flu Emergency.
- We've seen major die offs of wild migratory birds reported from a number of Midwest states, including Illinois, Missouri, and Louisiana, which appear to be due to the new D1.x genotype.
- Last week, we saw a report out of Galveston County, Texas regarding potential exposure of several individuals to an H5 infected wild bird brought into animal rescue and we've seen multiple reports of feline deaths from the virus, some linked to consuming raw milk and/or raw meat.
- In EID Journal: Influenza A(H5N1) Virus Clade 2.3.2.1a in Traveler Returning to Australia from India, 2024, we looked at an unexpected reassortment between older H5N1 clade 2.3.2.1a virus and the newer clade 2.3.4.4b clade in India.
- In Emerg. Microbes & Inf.: Marked Neurotropism and Potential Adaptation of H5N1 Clade 2.3.4.4.b Virus in Naturally Infected Domestic Cats, we looked at an outbreak of H5 in a house full of domestic cats, all of which died, many with severe neurological symptoms. The authors also documented a number of potentially significant mutations in these cats, along with demonstrating their ability to serve as a potential `mixing vessel' for influenza.
- In EID Journal: Replication Restriction of Influenza A(H5N1) Clade 2.3.4.4b Viruses by Human Immune Factor, 2023–2024, we looked at a paper on ways the H5 virus could potentially evade the MxA protein, which currently suppresses its replication in human hosts.
- In one of the more disconcerting reports of 2024, we looked at a study (Lancet Microbe: Novel Human-Type Receptor-Binding H5N1 Virus in Live Poultry Markets, China) which found signs of human adaptation in H5 viruses Chinese poultry.
- In EID Journal: Systematic Review of Avian Influenza Virus Infection and Outcomes during Pregnancy, we revisited the extreme toll novel flu viruses have often had on pregnant women, and their offspring.
Along with other, non-bird flu reports on Mpox, Seasonal flu & antiviral resistance, and novel swine flu viruses.
