Ain't No Cure For the Summer Bird Flu

 

#16,958

Were we not in the 32nd month of a Global SARS-CoV-2 pandemic which has claimed (well) in excess of 6 million lives, and in the 4th month of growing Monkeypox Epidemic affecting nearly 100 countries , the biggest infectious disease story of the summer might very well be the unprecedented spread and persistence of HPAI H5 avian flu around the world. 

While Europe and Asia are no strangers to seeing avian flu - particularly during the fall and winter months - the United States has been struck for the first time since 2015 (see above graphic), resulting in the loss of tens of millions of wild and commercially raised birds, and the spillover of the virus to numerous mammalian species (including 1 human infection). 

Unlike the epizootic of 2015 - which subsided once summer arrived - HPAI H5 remains active in both North America and in Europe. Notably, the virus has broadened its host range (see DEFRA: The Unprecedented `Order Shift' In Wild Bird H5N1 Positives In Europe & The UK), as it has continued to expand geographically. 

Although we are seeing less activity than we saw earlier this year, even in late August we continue to see daily reports of avian flu outbreaks in the United States, Europe, and even Asia. The following report comes overnight from the state of Georgia. 

Possible bird flu discovered after 700 vultures found dead at Noah’s Ark Sanctuary

By WSBTV.com News Staff August 22, 2022 at 9:22 pm EDT

HENRY COUNTY, Ga. — The Georgia Department of Natural Resources says they’re assessing and investigating the deaths of 700 hundred black vultures at the Noah’s Ark Animal Sanctuary in Locust Grove. The state has confirmed that those deaths are related to an avian influenza outbreak, commonly known as bird flu. 

Workers suspect a contaminated bird got into the resident vulture population. Efforts are underway to prevent the spread to other animals.

Noah’s Ark said in a statement that initial tests show that the H5N1 strain of Highly Pathogenic Avian Influenza (HPAI) was the cause of death.

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Also concerning, we've seen numerous reports of HPAI H5 infecting, and killing, non avian species. For the past two months we've been following the unusual mortality event in seals in Maine, and in Canada, which has been attributed to the HPAI H5 virus.  This update from NOAA Fisheries.

2022 Pinniped Unusual Mortality Event along the Maine Coast

Since June 2022, elevated numbers of harbor seal and gray seal mortalities have occurred across the southern and central coast of Maine. This event has been declared an unusual mortality event (UME).

  

Why are Seals Stranding?

Preliminary testing of samples has found some harbor and gray seals positive for highly pathogenic avian influenza (HPAI) H5N1. There is an ongoing HPAI H5N1 event North America that was first detected in early winter 2021. The first detections in Maine waterfowl were in February 2022. HPAI H5N1 has now been confirmed in 41 U.S. states and 11 Canada provinces, in commercial poultry, backyard flocks, nearly 90 species of wild birds, eight species of scavenging mammals, and now seals. NOAA Fisheries is working with our local, state, tribal, federal and international partners in the investigation of HPAI in seals. HPAI is a “zoonotic disease” that has the potential to spread between animals and people (and their pets).

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 We've seen similar spillovers into terrestrial mammals as well, including:

Two States (Michigan & Minnesota) Report HPAI Infection In Wild Foxes

Ontario: CWHC Reports HPAI H5 Infection With Severe Neurological Signs In Wild Foxes (Vulpes vulpes)

Netherlands DWHC Reports another Mammal (Polecat) Infected With H5N1

Human infections, have thankfully been very few and mild.  Nevertheless, just over 3 months ago the CDC Added Zoonotic Avian A/H5N1 Clade 2.3.4.4b To IRAT List. 

Last month, in PrePrint: HPAI H5N1 Infections in Wild Red Foxes Show Neurotropism and Adaptive Virus Mutations, we saw evidence from the Netherlands that Europe's avian H5N1 virus was adapting to its new-found mammalian hosts by acquiring the PB2-627K mutation.

PB2-627K can enable the virus to replicate more efficiently at the lower temperatures (33°C) commonly found in the respiratory tract of mammals, rather than the higher temperatures found in avian gastrointestinal tracts.

Although its threat to human health remains low, we continue to see evidence that HPAI H5 is slowly adapting to mammalian hosts, and so that status quo may not last forever.  A new study, which was previewed this week in Transboundary and Emerging Diseases, finds similar adaptations in an H5N8 virus in China.

H5N8 Subtype Avian Influenza Virus Isolated from Migratory Birds Emerging in Eastern China Possessed a High Pathogenicity in Mammals

Xinyu Miao,Mingcan Feng,Ouwen Zhu,Fan Yang,Yinyan Yin,Yuncong Yin,Sujuan Chen,Tao Qin,Daxin Peng,Xiufan Liu
First published: 21 August 2022

Influenza viruses are notoriously unpredictable, and often when we expect them to zig, they zag instead. Five years ago, H7N9 was on everyone's watch list, but following china's massive poultry vaccination program, that threat has (at least temporarily) receded. 

About all we can say with any certainty is that HPAI H5's impact over the past 2 years has been unprecedented, both in size, and in scope, and it continues to evolve.  

The virus is presumably spreading among birds in their high latitude summer roosting sites (see Norwegian Veterinary Institute : More HPAI (H5N5 & H5N1) Detected In Arctic (Svalbard)), and could return (as H5N1, H5N8, H5N5 or some other H5Nx subtype) with renewed vigor this fall. 

This recent, rapid spread and evolution of HPAI H5 has a lot of scientists genuinely worried (see Nature Why unprecedented bird flu outbreaks sweeping the world are concerning scientists).

While our hands are admittedly full with COVID, Monkeypox, polio, and the expected return of seasonal influenza this fall, we need to be preparing for the unexpected as well.  

Because nature has no qualms about piling on.