A Concerned Scientist @BE@qoto.org

I see some prominent people on Mastodon discussing the amazing speed at which bird flu has evolved from birds to mammals. Let's debunk.

"The first description of avian influenza (bird flu) dates to 1878 in northern Italy, when it was described as a contagious disease of poultry associated with high mortality, referred to as “fowl plague.” At the turn of the 20th century, it was determined that “fowl plague” was caused by a virus; however, it was not until 1955 that the virus was shown to be a type A influenza virus."

https://www.cdc.gov/flu/avianflu/timeline/avian-timeline-background.htm

Even just mammal to mammal spread was first scientifically documented 20 years ago.

https://wwwnc.cdc.gov/eid/article/10/12/04-0759_article

Just because you learned about something recently, it doesn't mean it just happened.

Separately, from a US-centric point of view, which is the view I think many people are taking this from, bird flu was first found in North America in 2021.

I have my suspicions about why mammal spread has been far more wide-spread in the last few years, but, I'm not sharing them as "fact" and I only wish others would do the same.

Another interesting article from @HelenBranswell at StatNews today on the subject.

https://www.statnews.com/2024/04/29/bird-flu-raw-milk-h5n1-risk-us-cattle/

One, don't drink raw milk, and be wary of cheeses that use raw milk. I once had a roommate who was a head cheese maker, and knowing the process there I'm a little less worried about cheeses, but, I'm a big fan of the precautionary principle.

“Expect the unexpected. That’s the situation we deal with here.”

I think this was an interesting portion:

"But H5N1 has more tricks up its sleeve than seasonal flu viruses do; it can infect organs other than the lungs. Kuiken noted that the virus has been seen to move into the liver, the central nervous system and the brain, among other tissues. He saw the latter when he experimentally infected cats in the mid-2000s. Similar results were seen when baby goats were infected with the virus on a Minnesota farm in March. Ten of the kids died; necropsies on five of them showed virus in the brains and other organs.

Many of the animal species infected in the wild have been reported to sustain damage outside of the respiratory tract. It’s believed these animals — bears, raccoons, seals, foxes, and a raft of other mammals — became infected by eating sick or dead wild birds or poultry infected with the virus.

“So many, many species, they get a brain infection and brain disease, not a pulmonary disease,” Kuiken said. “In some cases the disease is missed because people are expecting pneumonia. If the animal is found dead, they don’t see the neurologic signs, and they forget to test the brain.”

Human infection with flu occurs when people breathe viruses emitted by others into their upper respiratory tracts. But the shared real estate of the top of the respiratory and gastric tracts make it impossible to rule out the possibility that ingestion of food or drink that contained high levels of viable H5N1 virus could trigger infection, scientists said.

Krammer said there are several mechanisms that could come into play. “You could get infection of cells in the upper respiratory tract that could go down and cause lower respiratory tract infection. There could be a route where it’s really going to the olfactory bulb,” he said, going from there to the brain. “And there’s the other option that it really makes it through the stomach … and then you start an infection from the mid gut.”

Krammer said he thought that last option was unlikely; he thinks stomach acids would inactivate the virus. But Kuiken doesn’t believe that’s necessarily true, referring to his study of H5N1 in cats. Milk acts as a buffer, he said. “It’s the perfect fluid for [virus] reaching the intestine in an infectious state.”

Maria Van Kerkhove, acting head of the WHO’s department of epidemic and pandemic preparedness, pointed to another outbreak, involving another virus and another animal species — the MERS coronavirus, which spreads to people from camels — as an example of where ingestion of virus-laced milk may have triggered infection of a respiratory disease. Some cases of MERS were traced to the drinking of raw camel’s milk, Van Kerkhove said, though she noted it wasn’t generally possible to tease out whether it was the drinking of the milk or the act of milking that led to the infections. (Influenza viruses and coronaviruses belong to different families.)"

Statnews.com's update today with a few interesting tidbits again:

https://www.statnews.com/2024/04/26/h5n1-bird-flu-usda-cattle-testing-order-more-limited/

"farmers only have to test up to 30 animals in a given group. The guidance does not say how farmers should determine which 30 animals to test in larger groups that are being readied to be moved. The USDA did not respond to STAT’s questions about the rationale for the 30-animal cap."

"Under the new rules, cows that are to be moved between states must have samples collected and tested no more than a week prior to transport. A licensed or accredited veterinarian has to collect the samples — between 3 and 10 milliliters of milk per animal taken from each of the four teats. That’s very important, the USDA noted, because there have been reports of infected animals having virus in only one teat.

A strange feature of H5N1’s jump from birds into cows is that the virus seems to have developed an affinity for mammary tissue. Samples from sick cows show the highest levels of virus not in their noses but in their milk, suggesting that udders seem to be where H5N1 migrates to or infects."

"The USDA order does not apply to beef cattle or non-lactating dairy cattle, including calves, due to their lower risk profile, according to the guidance. But influenza researchers told STAT that not enough yet is known about the risks to non-lactating animals to leave them out."

34 herds in 9 states now confirmed:

https://www.aphis.usda.gov/livestock-poultry-disease/avian/avian-influenza/hpai-detections/livestock

But almost certainly far more widespread.

"On Friday, the FDA issued an update saying that tests of several samples of retail powdered infant and toddler formula were negative, indicating no presence of H5N1 viral fragments or whole virus. It provided no details on the quantity tested."

"At this time, there have been no reported cases of H5N1-positive dairy cattle exhibiting any signs of neurological disease in the U.S."