Mastodawn

1/ Three papers in latest #Eurosurveillance issue (03 Aug 2023) are on outbreaks of highly pathogenic #AvianInfluenza A(#H5N1) virus infection in animals. #HPAI

"Highly pathogenic avian influenza A(H5N1) virus infection on multiple fur farms in the South & Central Ostrobothnia regions of Finland, July 2023"

▶️ First reported on 14 July, an outbreak of avian influenza among farmed foxes, minks & raccoon dogs

▶️ Up to 27 July, animals on 20 farms have been affected

🔗: https://doi.org/10.2807/1560-7917.ES.2023.28.31.2300400

Eurosurveillance | Highly pathogenic avian influenza A(H5N1) virus infection on multiple fur farms in the South and Central Ostrobothnia regions of Finland, July 2023

Since mid-July 2023, an outbreak caused by highly pathogenic avian influenza A(H5N1) virus clade 2.3.4.4b genotype BB is ongoing among farmed animals in South and Central Ostrobothnia, Finland. Infections in foxes, American minks and raccoon dogs have been confirmed on 20 farms. Genetic analysis suggests introductions from wild birds scavenging for food in farm areas. Investigations point to direct transmission between animals. While no human infections have been detected, control measures are being implemented to limit spread and human exposure.

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Ed Hill Aug 4, 2023

2/ "Emergence and potential transmission route of avian influenza A (H5N1) virus in domestic cats in Poland, June 2023"

▶️ Reports the detection and genetic analysis of HPAI H5N1 viruses in ill cats in Poland during June 2023

▶️ Multiple cases reported across the country (28 domestic cats & one captive caracal)

▶️ Investigated potential transmission routes to discern the possible transmission pathway of the virus from birds to felines

🔗: https://doi.org/10.2807/1560-7917.ES.2023.28.31.2300390

Eurosurveillance | Emergence and potential transmission route of avian influenza A (H5N1) virus in domestic cats in Poland, June 2023

In June 2023, a fatal disease outbreak in cats occurred in Poland. Most cases tested in Poland (29 of 47) were positive for highly pathogenic avian influenza (HPAI) A (H5N1) virus. Genetic analyses revealed clade 2.3.4.4b with point mutations indicative of initial mammalian hosts adaptations. Cat viral sequences were highly similar (n = 21), suggesting a potential common infection source. To investigate possible infection routes, our group tested food samples from affected households. HPAI H5N1 virus was detected in one poultry meat sample.

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Ed Hill Aug 4, 2023

3/ "Outbreak of highly pathogenic avian influenza A(H5N1) clade 2.3.4.4b virus in cats, Poland, June to July 2023"

▶️ Article describes "an outbreak caused by HPAI H5N1 virus detected in 25 cats from different regions of Poland over a period of 3 weeks between the end of June & the beginning of July 2023"

▶️ "viruses were very similar to each other, indicating a common source of infection, which, however, has not yet been identified."

🔗: https://doi.org/10.2807/1560-7917.ES.2023.28.31.2300366

/end

Eurosurveillance | Outbreak of highly pathogenic avian influenza A(H5N1) clade 2.3.4.4b virus in cats, Poland, June to July 2023

Background Over a 3-week period in late June/early July 2023, Poland experienced an outbreak caused by highly pathogenic avian influenza (HPAI) A(H5N1) virus in cats. Aim This study aimed to characterise the identified virus and investigate possible sources of infection. Methods We performed next generation sequencing and phylogenetic analysis of detected viruses in cats. Results We sampled 46 cats, and 25 tested positive for avian influenza virus. The identified viruses belong to clade 2.3.4.4b, genotype CH (H5N1 A/Eurasian wigeon/Netherlands/3/2022-like). In Poland, this genotype was responsible for several poultry outbreaks between December 2022 and January 2023 and has been identified only sporadically since February 2023. Viruses from cats were very similar to each other, indicating one common source of infection. In addition, the most closely related virus was detected in a dead white stork in early June. Influenza A(H5N1) viruses from cats possessed two amino acid substitutions in the PB2 protein (526R and 627K) which are two molecular markers of virus adaptation in mammals. The virus detected in the white stork presented one of those mutations (627K), which suggests that the virus that had spilled over to cats was already partially adapted to mammalian species. Conclusion The scale of HPAI H5N1 virus infection in cats in Poland is worrying. One of the possible sources seems to be poultry meat, but to date no such meat has been identified with certainty. Surveillance should be stepped up on poultry, but also on certain species of farmed mammals kept close to infected poultry farms.

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Christian Testa Aug 4, 2023

@EdMHill it’s interesting that attention was garnered here, it seems, as a result of an informal excess deaths framework (e.g., noting that mortality was rapidly increasing) applied to livestock (in this case, the foxes, minks, raccoon dogs, etc).

I only skimmed the beginning of the article, but I was wondering — do we have a sense of if there is mammal to mammal transmission happening in this or related outbreaks?

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Ed Hill Aug 4, 2023

@ctesta My commentary on what the authors have presented for this outbreak event is there being plausible support for mammal to mammal transmission having occurred , but the data/evidence is not sufficient to attribute high confidence to exact transmission mechanisms.

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Ed Hill Aug 4, 2023

@ctesta Some quotes from the study (plus image from relevant section of the study)

▶️ "Phylogenetic analyses further suggest that several introductions from birds to the fur animals may have taken place but are also consistent with possible transmission among the fur animals themselves and potentially even between species"

▶️ "The exact mechanism of the transmission within and between farms is, however, not yet known."

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Christian Testa Aug 5, 2023

@EdMHill thanks for the update! much appreciated