Science
What you need to know about the bird flu outbreak, concerns about raw milk, and more
There is a bird flu outbreak going on. Here is what you need to know about it:
What is bird flu?
Bird flu is what’s known as a highly pathogenic avian influenza virus. The “highly pathogenic” part refers to birds, which the virus is pretty adept at killing. In virology speak, the virus is of the Influenza A type, and is called H5N1. The “H” stands for the protein Hemagglutinin (HA), of which there are 16 subtypes (H1-H16). The “N” is short for Neuraminidase (NA), of which there are 9 subtypes (N1-N9). There are many possible combinations of HA and NA proteins. The two known type A human influenza viruses are H1N1 and H3N2. (Two additional subtypes, H17N10 and H18N11, have been identified in bats).
When did this bird flu first appear?
The current strain of H5N1 circulating the globe originated in 1996, in farmed geese living in China’s Guangdong province. It quickly spread to other poultry and migrating birds. By the early 2000s, it had spread across southern Asia. By 2005, it was observed in the Middle East, Africa and Europe. In 2014, it showed up in North America, but appeared to peter out here while it still raged in Europe, the Middle East and Africa. In 2021, it showed up in wild birds migrating off Canada’s Atlantic coast. Since then, it has spread across North and South America.
What kinds of animals does bird flu effect?
Birds are the primary carriers and victims of the virus. Across the globe, hundreds of millions of wild and domestic birds have died. Since 2021, hundreds of U.S. poultry farms have had to “depopulate” millions of birds after becoming infected, presumably from sick, migrating wild birds. The virus is highly contagious among birds and has a nearly 100% fatality rate. Mammals, too have been infected and died. In most cases, these are scavenging or predatory animals that ate sick birds — and the virus has died in these animals and not become contagious between them. So far, 48 species of mammals have become infected. However, there have been a few cases in which it appears the virus may have spread between mammals, including on European fur farms, on a few South American beaches where elephant seals came to roost, and now among dairy cattle in the United States.
Can humans get bird flu?
Since 2003, when the virus first started spreading through southern Asia, there have been 868 cases of human infection with H5N1 reported, of which 457 were fatal — a 53% case fatality rate. There have been only two cases in the U.S. In 2022, a poultry worker was infected in Colorado and suffered only mild symptoms, including fatigue. In 2024, a dairy worker was infected in Texas and complained only of conjunctivitis, or pink eye.
Why is everyone paying attention to dairy cows?
On March 25, 2024, officials announced that dairy cows in Texas had been infected with bird flu. Since then, the virus has been found in 36 herds across nine states. There are no known cases in California. It is believed that there was a single introduction of the virus from wild bird exposure (either by passive exposure, or maybe from eating contaminated feed), that probably occurred in December in Texas. The virus has since been detected in milk. A study conducted by federal researchers found that 1 in 5 milk samples collected from retail stores had the virus. It is believed that the virus may be passing between cows and that there may be cows that show no symptoms. For the most part, it seems dairy cows only suffer mild illness when infected, and milk production slows. They clear the virus after a few weeks.
Is it safe to drink milk?
Yes — if it is pasteurized milk. Federal officials say the virus they have detected in pasteurized milk samples is inactive and will not cause disease. In the case of raw milk, they urge people to avoid it. That’s because they have found high viral loads in raw milk samples. In addition, studies of barn cats that have consumed raw milk have reported severe consequences. In one cluster of 24 barn cats, half of them died after consuming raw milk, with others suffering blindness, neurological distress and copious nasal discharge. The virus has not been found in sour cream or cottage cheese.
What’s the situation with wastewater?
As health officials and researchers scramble to understand how widespread avian flu is in cattle and the environment, they are analyzing municipal wastewater. One team from Emory University and Stanford University looked at 190 wastewater treatment sites in 41 states. They found a surge of Influenza A virus in the last several weeks at 59 sites. This does not necessarily mean there is bird flu at these sites. However, in places where the team has gone to investigate — including three in Texas where they knew there was H5N1 in dairy cattle — they have found bird flu. Influenza A is generally seasonal in humans — peaking from late fall to early spring. The surge the researchers noticed — including at several sites in California — started after the flu season had died down. Researchers in Texas have also detected H5N1 in the wastewater of nine of 10 cities they tested, all located in Texas. The CDC is also monitoring for Influenza A at roughly 600 sites across the nation.
Science
What’s in a Name? For These Snails, Legal Protection
The sun had barely risen over the Pacific Ocean when a small motorboat carrying a team of Indigenous artisans and Mexican biologists dropped anchor in a rocky cove near Bahías de Huatulco.
Mauro Habacuc Avendaño Luis, one of the craftsmen, was the first to wade to shore. With an agility belying his age, he struck out over the boulders exposed by low tide. Crouching on a slippery ledge pounded by surf, he reached inside a crevice between two rocks. There, lodged among the urchins, was a snail with a knobby gray shell the size of a walnut. The sight might not dazzle tourists who travel here to see humpback whales, but for Mr. Avendaño, 85, these drab little mollusks represent a way of life.
Marine snails in the genus Plicopurpura are sacred to the Mixtec people of Pinotepa de Don Luis, a small town in southwestern Oaxaca. Men like Mr. Avendaño have been sustainably “milking” them for radiant purple dye for at least 1,500 years. The color suffuses Mixtec textiles and spiritual beliefs. Called tixinda, it symbolizes fertility and death, as well as mythic ties between lunar cycles, women and the sea.
The future of these traditions — and the fate of the snails — are uncertain. The mollusks are subject to intense poaching pressure despite federal protections intended to protect them. Fishermen break them (and the other mollusks they eat) open and sell the meat to local restaurants. Tourists who comb the beaches pluck snails off the rocks and toss them aside.
A severe earthquake in 2020 thrust formerly submerged parts of their habitat above sea level, fatally tossing other mollusks in the snail’s food web to the air, and making once inaccessible places more available to poachers.
Decades ago, dense clusters of snails the size of doorknobs were easy to find, according to Mr. Avendaño. “Full of snails,” he said, sweeping a calloused, violet-stained hand across the coves. Now, most of the snails he finds are small, just over an inch, and yield only a few milliliters of dye.
Science
Video: This Parrot Has No Beak, But Is at the Top of the Pecking Order
new video loaded: This Parrot Has No Beak, But Is at the Top of the Pecking Order
By Meg Felling and Carl Zimmer
April 20, 2026
Science
Contributor: Focus on the real causes of the shortage in hormone treatments
For months now, menopausal women across the U.S. have been unable to fill prescriptions for the estradiol patch, a long-established and safe hormone treatment. The news media has whipped up a frenzy over this scarcity, warning of a long-lasting nationwide shortage. The problem is real — but the explanations in the media coverage miss the mark. Real solutions depend on an accurate understanding of the causes.
Reporters, pharmaceutical companies and even some doctors have blamed women for causing the shortage, saying they were inspired by a “menopause moment” that has driven unprecedented demand. Such framing does a dangerous disservice to essential health advocacy.
In this narrative, there has been unprecedented demand, and it is explained in part by the Food and Drug Administration’s recent removal of the “black-box warning” from estradiol patches’ packaging. That inaccurate (and, quite frankly, terrifying) label had been required since a 2002 announcement overstated the link between certain menopause hormone treatments and breast cancer. Right-sizing and rewording the warning was long overdue. But the trouble with this narrative is that even after the black-box warning was removed, there has not been unprecedented demand.
Around 40% of menopausal women were prescribed hormone treatments in some form before the 2002 announcement. Use plummeted in its aftermath, dipping to less than 5% in 2020 and just 1.8% in 2024. According to the most recent data, the number has now settled back at the 5% mark. Unprecedented? Hardly. Modest at best.
Nor is estradiol a new or complex drug; the patch formulation has existed for decades, and generic versions are widely manufactured. There is no exotic ingredient, no rare supply chain dependency, no fluke that explains why women are suddenly being told their pharmacy is out of stock month after month.
The story is far more an indictment of the broken insurance industry: market concentration, perverse incentives and the consequences of allowing insurance companies to own the pharmacy benefit managers that effectively control drug access for the majority of users. Three companies — CVS Caremark, Express Scripts and OptumRx — manage 79% of all prescription drug claims in the United States. Those companies are wholly owned subsidiaries of three insurance behemoths: CVS Health, Cigna and UnitedHealth Group, respectively. This means that the same corporation that sells you your insurance plan also decides which drugs get covered, at what price, and whether your pharmacy can stock them. This is called vertical integration. In another era, we might have called it a cartel. The resulting problems are not unique to hormone treatments; they have affected widely used medications including blood thinners, inhalers and antibiotics. When a low-cost generic such as estradiol — a medication with no blockbuster profit margins and no patent protection — runs into friction in this system, the friction is not random. It is structural. Every decision in that chain is filtered through the same corporate profit motive. And when the drug in question is an off-patent estradiol patch that has negligible profit margins because of generic competition but requires logistical investment to keep consistently in stock? The math on “how much does this company care about ensuring access” is not complicated.
Unfortunately, there is little financial incentive to ensure smooth, consistent access. There is, however, significant financial incentive to steer patients toward branded alternatives, or simply to let supply tighten — because the companies aren’t losing much profit if sales of that product dwindle. This is not a conspiracy theory: The Federal Trade Commission noted this dynamic in a report that documented how pharmacy benefit managers’ practices inflate costs, reduce competition and harm patient access, particularly for independent pharmacies and for generic drugs.
Any claim that the estradiol patch shortage is meaningfully caused by more women now demanding hormone treatments is a distraction. It is also misogyny, pure and simple, to imply that the solution to the shortage is for women’s health advocates to dial it down and for women to temper their expectations. The scarcity of estradiol patches is the outcome of a broken system refusing to provide adequate supply.
Meanwhile, there are a few strategies to cope.
- Ask your prescriber about alternatives. Estradiol is available in multiple formulations, including gel, spray, cream, oral tablet, vaginal ring and weekly transdermal patch, which is a different product from the twice-weekly patch and may be more consistently available depending on manufacturer and region.
- Consider an online pharmacy. Many are doing a good job locating and filling these prescriptions from outside the pharmacy benefit manager system.
- Call ahead. Patch shortages are inconsistent across regions and distributors. A call to pharmacies in your area, or a broader geographic radius if you’re able, can locate stock that your regular pharmacy doesn’t have.
- Consider a compounding pharmacy. These sources can sometimes meet needs when commercially manufactured products are inaccessible. The hormones used are the same FDA-regulated bulk ingredients.
Beyond those Band-Aid solutions, more Americans need to fight for systemic change. The FTC report exists because Congress asked for it and committed to legislation that will address at least some of the problems. The FDA took action to change the labeling on estrogen in the face of citizen and medical experts’ pressure; it should do more now to demand transparency from patch manufacturers.
Most importantly, it is on all of us to call out the cracks in the current system. Instead of repeating “there’s a patch shortage” or a “surge in demand,” say that a shockingly small minority of menopausal women still even get hormonal treatments prescribed at all, and three drug companies control the vast majority of claims in this country. Those are the real problems that need real solutions.
Jennifer Weiss-Wolf, the executive director of the Birnbaum Women’s Leadership Center at New York University School of Law, is the author of the forthcoming book “When in Menopause: A User’s Manual & Citizen’s Guide.” Suzanne Gilberg, an obstetrician and gynecologist in Los Angeles, is the author of “Menopause Bootcamp.”
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