Avian flu has infected dairy cows in more than a dozen states – a microbiologist explains how the virus is spreading
The H5N1 avian flu has spread from birds to dairy cows, causing significant outbreaks and posing risks to farm workers and other animals, though pasteurized milk remains safe.
Last Updated on September 21, 2024 by Daily News StaffAlthough H5N1 typically infects wild birds, the virus has spilled over into domesticated animal populations, like dairy cows. Peter Cade/Stone via Getty Images
The Conversation U.S. asked immunologist and microbiologistJenna Guthmiller from the University of Colorado Anschutz Medical Campus to explain the historical roots of H5N1, its mode of transmission and how to avoid coming into contact with it.
What is H5N1?
H5N1 is a subtype of influenza A viruses. Other commonly known influenza A virus subtypes include H1N1 and H3N2, which cause seasonal outbreaks in humans.
Unlike H1N1 and H3N2, H5N1 largely infects wild birds, with waterfowl such as ducks and geese being the natural reservoirs for H5N1 viruses. Most H5N1 viruses are highly pathogenic avian influenza, meaning spillovers into other bird populations can lead to high mortality rates, including domesticated poultry.
H5N1 viruses were first identified in 1959 due to an outbreak in domesticated chickens in Scotland. In 1996, waterfowl were identified as the natural reservoir for H5N1.
Researchers have documented the current H5N1 strain in numerous mammals, with it largely affecting aquatic mammals like seals and scavenger mammals. Sporadic spillover to domestic mammals has been recorded, including to minks, goats and alpacas.
Dairy cow-associated H5N1 viruses have since jumped back into wild birds, and recent outbreaks in domestic poultry resembled H5N1 in dairy cows. Between May and July 2024, 13 confirmed H5N1 infections have occurred in humans, with all cases directly linked to dairy farms and poultry culling. https://www.youtube.com/embed/jhKI2Zskplg?wmode=transparent&start=0 The concern is that the virus could evolve to allow human-to-human transmission.
Why did the avian flu become more widespread?
It is unclear why H5N1 has become such a widespread problem. H5N1, like all influenza viruses, rapidly mutates to infect new hosts. However, H5N1 has several features that could increase its host range.
First, H5N1 viruses use a protein called hemagglutinin that allows H5N1 to infect with new hosts.
Lastly, H5N1 viruses are mutating genes associated with replication and immune evasion that are known to increase the infection of mammals.
Together, these factors could heighten H5N1 transmission and increase H5N1 spillover to mammals.
How is the strain transmitted to dairy cattle?
H5N1 viruses are largely causing infections in the mammary glands of cattle rather than the respiratory tract, which is the main site of infection for other influenza viruses in mammals. Recent studies have shown that the mammary tissue has receptors for H5N1, which could make this tissue susceptible to infection.
Since the infection is largely restricted to the mammary glands, researchers believe that H5N1 is being transmitted to cows by contaminated milk equipment, particularly the milking apparatus that attaches to the cow udders. Transmission across farms is due to infected cattle movement and shared equipment and personnel across dairy farms.
H5N1 does not pose a risk to the general public, as this virus is not known to transmit between people. As all known cases were those with direct contact with infected animals, people with occupational exposure to H5N1-infected cows and poultry continue to be at the greatest risk of infection.
People with occupational hazards should be aware of the H5N1 symptoms – similar to those of a cold – such as congestion, sore throat and fatigue, as well as conjunctivitis, more commonly known as pink eye. For more information, see the Centers for Disease Control and Prevention’s webpage on avian influenza in people.
Domestic and wild animals near dairy farms are at high risk of infection. Particularly, barn cats that have been fed raw milk have been reported dead on dairy farms with infected cows, with these animals coming back positive for H5N1.
In addition, spillover of H5N1 to other domesticated farm animals near infected dairy cows has been recorded.
What are the best ways to keep farm workers safe?
Using personal protective equipment, such as goggles and gloves, remains the best way to prevent the transmission of H5N1 to humans and from humans back to animals. People working around poultry or dairy cattle should also be aware of biosecurity measures, such as not wearing the same clothes and boots when traveling from one farm to another.
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Hollywood Legend Rob Reiner and Wife Found Dead; Son in Custody
Renowned filmmaker Rob Reiner and his wife, Michele Singer Reiner, were found dead in their Los Angeles home in a reported homicide. Police have arrested their son in connection with the case, and tributes are pouring in.
Director Rob Reiner participates in a discussion following a screening of the film LBJ at the LBJ Presidential Library in Austin, Texas on Saturday October 22, 2016 On Saturday evening October 22, 2016, the LBJ Presidential Library held a sneak peek of Rob Reiner’s new filmÊLBJ, starring Woody Harrelson as the 36th president. The film, which premiered at the Toronto International Film Festival in September, chronicles the life and times of Lyndon Johnson who would inherit the presidency at one of the most fraught moments in American history. Following the screening, director Rob Reiner, actor Woody Harrelson, and writer Joey Hartstone joined LBJ Library Director Mark Updegrove on stage for a conversation about the film. LBJ Library photo by Jay Godwin 10/22/2016
Hollywood Legend Rob Reiner and Wife Found Dead; Son in Custody
December 15, 2025
Renowned filmmaker and actor Rob Reiner, 78, and his wife Michele Singer Reiner, 68, were found dead in their Brentwood, Los Angeles home on Sunday, authorities say. Emergency responders were called to the residence Sunday afternoon, where both were discovered with fatal wounds consistent with a stabbing. Police are treating the case as a double homicide.
Los Angeles police arrested the couple’s 32-year-old son, Nick Reiner, in connection with the deaths. He is being held in custody as investigators continue to piece together the circumstances surrounding the incident.
2016 SAMHSA Voice Awards
Reiner was one of Hollywood’s most influential figures, known for his work as a director, producer and actor. His career spanned decades, from early television fame to directing beloved films that shaped American cinema.
Friends, colleagues and public figures have begun sharing tributes and reactions to the news as the investigation is ongoing.
More details will be updated as they become available.
🇯🇵 Japan Earthquake Update — What You Need to Know (December 2025)
Japan Earthquake Update — A powerful magnitude 7.5 earthquake struck off the coast of Aomori, Japan, triggering tsunami warnings and a rare megaquake advisory. Here are the latest updates on damage, aftershocks, government response, and ongoing seismic risks as of December 2025.
🇯🇵 Japan Earthquake Update — What You Need to Know (December 2025)
On December 8, 2025, a powerful earthquake — measured at magnitude 7.5 (7.6 by the U.S. Geological Survey) — struck offshore of Aomori Prefecture in northern Japan around 11:15 p.m. JST. The quake was deep enough (about 44 km) to be felt over a wide area, with intense shaking registering across northern Honshu and parts of Hokkaido.
🌊 Immediate Impact — Tsunami & Injuries
Tsunami Warnings were promptly issued along the Pacific coasts of Hokkaido, Aomori and Iwate. Authorities initially feared waves up to ~3 meters high, prompting evacuations. In the end, only small tsunami waves — up to about 70 cm — were observed, and all warnings were lifted by early Tuesday morning. At least 50 plus people have been injured, mostly lightly, due to falling objects and minor structural impacts from the shaking.
Across the affected prefectures, emergency crews continue damage assessments and are checking roads, buildings, utilities and other infrastructure for safety concerns. Some power outages and transport disruptions (train suspensions) were reported in the aftermath.
🧠 Rare “Megaquake Advisory” Issued
Japan’s meteorological authority, the Japan Meteorological Agency (JMA), has issued a megaquake advisory following the M 7.5 quake — a rare alert indicating elevated seismic risk. This advisory:
Does not predict when (or if) a larger earthquake will occur. Signals that the probability of a more powerful quake (M 8.0+) has increased temporarily for the next several days or week. Specifically, a formerly tiny ~0.1% weekly chance has risen to roughly ~1 %. Applies along a long stretch of Japan’s Pacific coast — from Chiba Prefecture in the south up through Hokkaido in the north — where the Pacific tectonic plate is actively subducting beneath Japan.
Officials emphasize that this is an advisory, not a prediction, and it’s issued to encourage preparedness: securing furniture, reviewing evacuation plans, and keeping emergency kits ready.
🌏 Aftershocks and Continued Seismic Activity
Even after the main quake, strong aftershocks have been recorded in the region — including quakes in the magnitude 5–6 range. This ongoing activity is consistent with a typical aftershock sequence but reinforces the public safety message to stay alert.
Later smaller tremors — including a reported M 6.0 event — have been felt near Aomori and Hokkaido, though none have triggered additional tsunami warnings.
🛡 Government Response & Public Safety
The Japanese government has mobilized an emergency task force to:
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Assess damage and coordinate response efforts across affected regions. Monitor infrastructure — including roads, utilities, and nuclear facilities — for any damage or safety issues. Keep the public informed and ready for possible aftershocks or other quakes.
Schools, businesses and local municipalities continue to evaluate safety conditions and may adjust operations accordingly.
📌 What This Means for Residents & Visitors
✔ Immediate tsunami danger has passed, but vigilance is still needed due to aftershocks.
✔ Preparedness is crucial, especially in coastal and northern regions that felt the quake strongest.
✔ If you’re in Japan or planning travel, follow JMA updates and local government advisories for current regional guidance.
🧭 In Summary
Japan is dealing with the impacts of a major offshore earthquake that shook the northern Pacific coast and prompted widespread alerts. Although immediate tsunami threats were limited and damage appears relatively light so far, a rare megaquake advisory remains in effect — not as a definitive forecast, but as a cautionary alert to stay prepared in the coming days.
Despite this elevated alert level, experts stress that while seismic risk is higher than normal, a massive quake is not imminent and the advisory’s purpose is to keep people ready rather than alarmed.
Links open in a new tab. Please follow official JMA updates for real-time alerts.
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How China cleaned up its air pollution – and what that meant for the climate
How China cleaned up its air pollution: Beijing’s air quality went from hazardous to good while Delhi and Lahore still struggle. Discover how China dramatically reduced pollution since 2013—and why cleaner air may have unintended consequences for global warming and climate change.
Delhi: 442. Lahore: 334. Beijing: 16. These are the levels of PM 2.5, one of the principle measures for air pollution, on November 19. As Pakistanis and Indians struggle with hazardous air quality, in Beijing – a city once notorious for its smog – the air quality is currently rated as good. Ahead of the 2008 Beijing Olympics, the Chinese government was so concerned about pollution that it introduced temporary restrictions on cars, shut down factories and stopped work on some construction sites. The measures worked and one study later found that levels of air pollution were down 30% during the period when the temporary Olympic restrictions were in place. It would take a few more years before the Chinese government implemented a clean air action plan in 2013. Since then, China has achieved a dramatic improvement in its air quality. In this episode of The Conversation Weekly podcast, we speak to Laura Wilcox, a professor at the National Centre for Atmospheric Science at the University of Reading in the UK, to understand how China managed to clean up its air pollution. But Wilcox’s recent research uncovered some unintended consequences from this cleaner air for the global climate: the pollution was actually helping to cool the atmosphere and by taking it away, it may have accelerated global warming. Wilcox explains:
What we’re seeing is a removing of cooling that’s revealing warming that’s already there. So the air pollution isn’t the cause of the warming. It’s just letting us see stuff that we’ve already done.
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Gemma Ware, Host, The Conversation Weekly Podcast, The Conversation This article is republished from The Conversation under a Creative Commons license. Read the original article.
