Bird flu is no longer limited to birds. The H5N1 strain of influenza was first detected in barnyard geese and chickens in the late 1990s. An outbreak in Hong Kong in 1997 made 18 people sick and six of them died. Most people in the US have ignored avian influenza, though. It seemed far away. But bird flu is starting to infect humans in the US. A third case reported this week suggests that the infection can now enter the lungs. That means it might spread more easily from person to person.
From Birds To Animals to Humans!
Bird flu did not stay put in Asian countries. H5N1 caused a lot of economic disruption for poultry farmers who had to cull their flocks. Millions of chickens and turkeys were killed to try to slow the spread of the virus. However, wild birds have carried it around the world and the virus has also infected mammals, including mink, foxes, bears, raccoons, mountain lions, alpacas, polar bears and sea lions.
Like other influenza viruses, H5N1 has mutated over the years. That is what has allowed it to move into mammals. Dairy cattle in Texas, Michigan, Ohio, South Dakota, New Mexico, Kansas, Idaho, Texas and North Carolina have also been infected. At last count over 70 dairy herds have been infected.
We just read an alarming report posted on bioRxiv, June 1, 2024:
Researchers at the University of California, Davis, School of Veterinary Medicine worked with scientists at the National Institute of Agricultural Technology in Argentina. They have just reported mammal-to-mammal viral transmission of H5N1:
“Since 2020, the world has witnessed an unprecedented global epizootic of H5N1 clade 2.3.4.4b viruses with a catastrophic ecological impact on wildlife species, including pinnipeds [mammals with front and rear flippers such as seals, walruses and sea lions]. Although H5N1 HPAI viruses were previously implicated in mortalities of harbor seals (Phoca vitulina) and gray seals (Halichoerus grypus) in Europe in 2016–2021 and in North America in May–July 2022 the magnitude of those mortalities (<200 deaths in total) would pale in comparison with the impacts that ensued when these viruses arrived in South America. At least 30,000 sea lions have died in Peru, Chile, Argentina, Uruguay and Brazil. In addition, HPAI caused the largest mortality event of elephant seals recorded to date, with the death of >17,000 pups and an unknown number of adults at bioRxiv; this version posted June 1, 2024.”
That was a bit technical. The bottom line is that marine mammals have caught H5N1. It is spreading rapidly and killing large numbers of these animals. If the virus can adapt and spread in these species, it may well do the same thing in humans. We will get to that momentarily.
Mice Are Now Infected!
Researchers in New Mexico have discovered house mice have become infected with H5N1. They presumably caught this virus from cows. What’s scary about this discovery is that mice live in close proximity to humans. Most people do not hang out around cows. But like it or not, mice hang out around us. They pee and poop and those leavings may contain active virus.
By the way, cats in Texas have been dying. It is thought that they caught H5N1 from raw milk on farms where the virus was detected in cows.
A New York Times article (June 5, 2024) reveals why mammal to mammal transmission is scary:
“The researchers found H5N1 in the windpipes, lungs and brains of carcasses of sea animals. It is unclear whether the virus spread through the air or through some other route. But in lab experiments, the virus has been shown to be transmissible through air and via direct contact among ferrets.”
People Are Catching Bird Flu!
First, a farm worker in Texas came down with the H5N1 virus, presumably from the cattle he was tending. Then a second farm worker was infected. Both seemed to have mild symptoms limited to their eyes. Public health authorities were getting nervous, but they reassured the public that there was no need to worry, the virus was not a big deal in humans…yet.
Then a third person showed up with bird flu.More worrisome, he reported congestion, a sore throat and a cough, indicating lung involvement. That could mean the virus is adapting to humans and that it could move between people. However, the CDC was unable to pull enough viral DNA from this patient to determine if the virus has indeed mutated.
A Death in Mexico City:
Now, though, the World Health Organization is getting very nervous. It confirms the first human death linked to bird flu. The patient was 59 years old and was hospitalized in Mexico City. He was suffering from shortness of breath, fever, nausea and diarrhea. Mexican health officials report that this person was not a farm worker and did not have exposure to poultry or other animals. He died on April 24, 2024.
The first human death has tripped alarm bells in the US. June 5, 2024 was the first day news sources in the US confirmed a human death linked to H5N2. While this particular patient had a number of health problems prior to infection with avian influenza, the fact that the virus seemingly contributed to his death is alarming.
Can Avian Influenza Spread from Person to Person?
That question is keeping epidemiologists awake at night.
CNN reports (June 5, 2024):
“Of 17 people at the hospital who’d been in contact with the patient, no further cases were identified. Twelve additional contacts were identified near the person’s residence, and seven of those had symptoms, but testing of samples from these cases didn’t identify Covid-19 or any type of flu. Scientists are now testing blood samples to see whether they can find antibodies that would point to past infections.”
If avian influenza can spread directly from one person to another, it could set off a new flu epidemic. That is really the biggest worry bird flu has triggered for public health authorities. Having just lived through one pandemic in which a novel virus infected a lot of people, no one wants a repeat of that scenario.
Got Milk?
People are concerned about eating meat or drinking milk from infected cattle. Experts believe that pasteurized milk and well-cooked meat should be safe for consumption, even if they came from an infected animal.
What We Said About Bird Flu in 2005:
As we pointed out, people have been concerned about bird flu since just before the turn of the 21st century. Here is a question from a reader with the answer we offered in 2005.
Q. I’m seeking advice regarding “bird” flu. I’d like to try to take precautions now if I can. Is it too late to get Tamiflu?
What about masks? My husband would cringe if he knew I was asking this, but I wonder if it makes sense to purchase a serious mask, in case the flu does develop here in the US.
What other precautions might we take? I’m really bothered by how little our government has done regarding this flu, and I’d like to do what I can to look out for my family and friends.
A. No one knows yet whether the avian flu (H5N1) will mutate into a virus that spreads easily from one human to another. So far, the people who have gotten sick with this potentially lethal virus seem to have caught it from infected birds.
Oseltamivir (Tamiflu) appears to be effective against the H5N1 flu. Some countries are stockpiling this antiviral drug against the possibility of a pandemic. The UK, for example, has enough on hand to treat 25 percent of its population. In the US, stockpiles would cover less than 1 percent.
If your physician prescribes Tamiflu, you will be able to fill the prescription. The manufacturer assures us that there are adequate supplies for the coming flu season. [Remember, this was 1995.] Whether a surgical mask or something even more sophisticated could protect you is unclear.
Final Words:
That was our answer nearly 30 years ago. We hoped that bird flu would eventually disappear and not infect very many people. Sadly, H5N1 did not disappear. It has spread around the world and is now infecting a wide range of animals.
Wastewater Data Are Disconcerting:
In another development, WastewaterSCAN recently launched a dashboard for avian flu. It detected the virus in wastewater from more than ten places, most of them in Michigan and Texas, including Amarillo and Dallas.
The program has also detected H5 DNA fragments in San Francisco city wastewater. This suggests that there may be undetected infections in humans.
It remains to be seen whether it will be easily transmitted from human to human and whether the infection will become nasty. That is the biggest worry facing public health officials in North America.
Please share this article with friends and family so that they can stay abreast of this rapidly evolving story. We promise to keep you up-to-date on any significant developments.
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