A Review of Significant HPAI H5 Related Events - Dec 8th Follow up - Dec 23rd Update

[Michael Coston]

A Review of Significant HPAI H5 Related Events Over The Past 3 Weeks

CDC Case Count 11/10/24




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While it may not tell us where HPAI H5 will go in the days and weeks ahead, the events of the past 21 days have demonstrated how quickly the status quo with avian flu can change.

On October 21st, the CDC counted 27 human H5 infections in the United States in 2024.​

Three weeks later that number is officially 46 (a gain of 19), but this doesn't include 4 cases confirmed by states (California & Washington) but not the CDC, a 2nd (strongly suspected) case in Missouri, or any of the 8 cases turned up last week by retrospective serology tests.

Three weeks ago, both the United States and Canada had gone months without substantial outbreaks in poultry, but between them have since reported > 40 outbreaks. ​

At the same time the known number of American dairy herds infected by H5N1 has increased by 46% (from 324 to 473), across (now) 15 states.

All of that by itself would be concerning, but this doesn't begin to scratch the surface of H5 related events of the past 3 weeks. With that in mind, a mini review of 10 other H5 avian flu related events or revelations from the past 21 days.

• Starting with the oldest, on October 21st the state of Washington announced their First Presumed Human Infections with H5 (n=4), in exposed poultry cullers. We learned that this outbreak was due to a new genotype D1.1, and as of today, they are reporting 14 human cases.

• On October 24th, we got the long awaited Serology Results On Missouri H5 Patient's Contacts, which found no evidence of transmission to HCWs, but did strongly suggest a housemate was infected at the same time as the index case. The source of these infections has yet to be identified.

• On October 28th, in Nature: A Human Isolate of Bovine H5N1 is Transmissible and Lethal in Animal Models, we learned that the first Texas H5 isolate could be transmitted through the air between separated ferrets, that it might be capable of binding to and replicating in human respiratory tract cells, and that oseltamivir (Tamiflu) might not be as effective in treating it as Baloxivir.

• On October 30th, the USDA Reported the 1st Detection of HPAI H5N1 in Swine (Oregon), once again with another new genotype D1.2, which had infected poultry on the same farm. A week later (Nov 7th) the USDA Confirmed a 2nd Pig on Oregon Farm Tested Positive.

• On October 31st, Utah Became the 15th State To Report HPAI H5N1 In Cattle (n=8) a little more than two weeks after an outbreak of the B3.13 `bovine' genotype was detected in a large poultry operation in Cache County. The number of infected herds was last reported to be 13.

• On Nov 2nd the CDC Updated their Results On Texas H5N1 Virus In Ferrets, reporting that the virus transmitted in ferrets more efficiently than initially reported, and warning that `The results suggest this virus has the potential to cause severe illness in people'.

• On Nov 3rd, the Los Angeles County Health Dept. issued a Statement on H5 Avian Flu Detected In Wastewater, and while an animal source is suspected, human infections could not be ruled out.

• On Nov 7th, in MMWR: Serologic Evidence of Recent Infection with HPAI A(H5) Virus Among Dairy Workers we learned that 7% of (115) farmworkers tested positive for antibodies for H5, although half of them reported remembering no illness, and the other half only mild complaints. An early study had found no evidence of sub-clinical infection.

• That MMWR study prompted a major release of revised guidance by the CDC on Nov 8th, calling for - among other things - expanded testing of exposed, but asymptomatic, individuals.

• And last, but not least, on Nov 9th Canada: B.C. Govt Announces Presumptive Positive H5 Case In a Teenager. Details are scant, but this is the first case reported by Canada.

This is not a comprehensive list, and some honorable mentions over the past 3 weeks include:

• reports on the rise of H5N5 in Europe and the UK

• a preprint on how Immune History Shapes Human Antibody Responses to H5N1 Influenza viruses

• a preprint on the Emergence of a Novel Reassortant Clade 2.3.2.1c Avian Influenza in Cambodia

• a Eurosurveillance report on (HPAI) H5 virus Exposure in Domestic & Rural Stray Cats, the Netherlands

• and a USDA Press Release On Plans for Enhanced Testing For H5N1 in Bulk Milk.

Whether past is prologue remains to be seen - but based on the events of the past few weeks - we could be in for a bumpy ride.


https://afludiary.blogspot.com/2024/11/a-review-of-significant-hpai-h5-related.html​

 

[Michael Coston]

An Overview of Significant HPAI H5 Related Events Over The Past 4 Weeks

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Twenty-eight days, and 66 blog entries ago, we took a look back at the previous 3 weeks of rapid-fire developments surrounding HPAI H5, and on several fronts the pace has only quickened since then.

Admittedly, H5N1 isn't the only threat we are concerned with (see DRC `Mystery Virus' investigation), but it is the most pressing, and currently the closest to home.​

Over the past 4 weeks:

• The number of confirmed H5 human cases in the U.S. has increased by 12, to 58 (with several more announced by states, but not yet confirmed by the CDC.) If you count serologically confirmed cases (the CDC doesn't) - and those in the pipeline - we are well over 70 cases.

• The number of known infected dairy herds has grown from 473 to > 720 (a 65% increase), and a 16th State (Nevada) is now reporting cases.

• Over the past 4 weeks more than 9 million birds from 78 flocks across 8 states have been infected (and lost) due to H5N1 in the United States, and Canada has reported > 50 outbreaks in poultry.

• According to the Marin County Health Dept. they are investigating a second Bay Area child with suspected H5 infection, and currently no known risk exposure. If confirmed, this would become the 3rd `community' case, not linked to occupational exposure.

• Hawaii reported H5 in wastewater samples on Nov 13th, and at least two outbreaks in captive and/or wild birds the following week, marking the first known detections in that state.

In case you missed them, some significant H5 events over the past 4 weeks (from oldest to newest) include:

• On November 13th Canada's PHAC confirmed their H5 infected teenager was infected with genotype D1.1 (not the bovine genotype). The patient, at last report, is sill in intensive care and on a ventilator, and no risk exposure has been identified.

• On Nov 20th, in Preprint: Enhanced Encephalitic Tropism of Bovine H5N1 Compared to the Vietnam H5N1 Isolate in Mice we looked research suggesting the bovine genotype is far more neurotropic in lab animals (mice) than its ancestral strains.

• On Nov 22nd, the CDC Confirmed H5N1 Infection In A Child from Alameda county, California, becoming the second U.S. infection not linked to occupational exposure.

• On Nov 25th California announced the first of (now 3) recalls of raw milk products due to H5 contamination.

• On Nov 27th Hong Kong Conducted a Coordinated Avian Flu Drill `Amazonite'

• On Dec 1st we looked at the continued expansion and spread of H5N5 in both Canada and Europe.

• On Dec 2nd, in Nature: Influenza A(H5N1) Shedding in Air Corresponds to Transmissibility in Mammals we saw evidence that H5N1 is slowly becoming more transmissible.

• On Dec 3rd the UK announced their intent to purchase > 5 million doses of H5N1 vaccine.

• On Dec 4th PAHO issued an Epidemiological Alert urging all Member nations to `. . . ensure preparedness for a potential influenza pandemic at all levels (14, 15).'

• On Dec 6th, in Science: A Single Mutation in Bovine Influenza H5N1 Hemagglutinin Switches Specificity to Human Receptors NIH researchers warned that H5 could be as little as `one mutation away' from becoming more transmissible in humans.

And those are just the highlights. We also saw evidence of H5N1 spillover into horses, WOAH's updated statement on H5N1 in Cattle, the USDA's belated Federal order to Begin a National Milk Testing Strategy for Avian Flu, among others.

While the trends are ominous, we still don't know if H5N1 is capable of adapting well enough to humans to spark a pandemic. Of course, by the time we have proof positive, it will be too late to act.​

Which is why last weekend I urged that my readers begin to prepare as if another pandemic may be in the offing (see A Personal Pre-Pandemic Plan).

Hopefully we'll get lucky, and won't have to face another one for years.​

But a little preparedness today could go a long ways towards mitigating a crisis tomorrow.


https://afludiary.blogspot.com/2024/12/an-overview-of-significant-hpai-h5.html​

 

[Michael Coston]

Review: Significant HPAI H5 Related Events Over The Past 2 Weeks

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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 case you missed them, some significant H5 publications from past 2 weeks (from oldest to newest) include:

• 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.

These are just some of the highlights, you'll find other reports on:

• Virus Evolution: Recurring Incursions & Dissemination of Novel Eurasian-origin H5Nx Avian Influenza Viruses in Atlantic Canada

• Updated joint FAO/WHO/WOAH public health assessment of recent influenza A(H5) virus events in animals and people

• ECDC/EFSA Quarterly Avian Influenza Overview Sept 2024 - Dec 2024

• LA County Issues Another Raw Milk Warning

• China CDC Weekly: Infection Tracing and Virus Genomic Analysis of Two Cases of Human Infection with Avian Influenza A(H5N6) — Fujian Province, China

Along with other, non-bird flu reports on Mpox, Seasonal flu & antiviral resistance, and novel swine flu viruses.


https://afludiary.blogspot.com/2024/12/review-significant-hpai-h5-related.html
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