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.
Although 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.
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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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A mourner holds a portrait of Pope Francis at the Basílica de San José de Flores in Buenos Aires, a church where the pope worshipped in his youth.
AP Photo/Gustavo GarelloMolly Jackson, The Conversation
Pope Francis, whose papacy blended tradition with pushes for inclusion and reform, died on April, 21, 2025 – Easter Monday – at the age of 88.
Here we spotlight five stories from The Conversation’s archive about his roots, faith, leadership and legacy.
1. A Jesuit pope
Jorge Mario Bergoglio became a pope of many firsts: the first modern pope from outside Europe, the first whose papal name honors St. Francis of Assisi, and the first Jesuit – a Catholic religious order founded in the 16th century.
Those Jesuit roots shed light on Pope Francis’ approach to some of the world’s most pressing problems, argues Timothy Gabrielli, a theologian at the University of Dayton.
Gabrielli highlights the Jesuits’ “Spiritual Exercises,” which prompt Catholics to deepen their relationship with God and carefully discern how to respond to problems. He argues that this spiritual pattern of looking beyond “presenting problems” to the deeper roots comes through in Francis’ writings, shaping the pope’s response to everything from climate change and inequality to clerical sex abuse.
2. LGBTQ+ issues
Early on in his papacy, Francis famously told an interviewer, “If someone is gay and he searches for the Lord and has good will, who am I to judge?” Over the years, he has repeatedly called on Catholics to love LGBTQ+ people and spoken against laws that target them.
An LGBTQ couple embrace after a pastoral worker blesses them at a Catholic church in Germany, in defiance of practices approved by Rome.Andreas Rentz/Getty Images
But “Francis’ inclusiveness is not actually radical,” explains Steven Millies, a scholar at the Catholic Theological Union. “His remarks generally correspond to what the church teaches and calls on Catholics to do,” without changing doctrine – such as that marriage is only between a man and a woman.
Rather, Francis’ comments “express what the Catholic Church says about human dignity,” Millies writes. “Francis is calling on Catholics to take note that they should be concerned about justice for all people.”
3. Asking forgiveness
At times, Francis did something that was once unthinkable for a pope: He apologized.
He was not the first pontiff to do so, however. Pope John Paul II declared a sweeping “Day of Pardon” in 2000, asking forgiveness for the church’s sins, and Pope Benedict XVI apologized to victims of sexual abuse. During Francis’ papacy, he acknowledged the church’s historic role in Canada’s residential school system for Indigenous children and apologized for abuses in the system.
But what does it mean for a pope to say, “I’m sorry”?
Members of the Assembly of First Nations perform in St. Peter’s Square at the Vatican on March 31, 2022, ahead of an Indigenous delegation’s meeting with Pope Francis.AP Photo/Alessandra TarantinoAnnie Selak, a theologian at Georgetown University, unpacks the history and significance of papal apologies, which can speak for the entire church, past and present. Often, she notes, statements skirt an actual admission of wrongdoing.
Still, apologies “do say something important,” Selak writes. A pope “apologizes both to the church and on behalf of the church to the world. These apologies are necessary starting points on the path to forgiveness and healing.”
4. A church that listens
Many popes convene meetings of the Synod of Bishops to advise the Vatican on church governance. But under Francis, these gatherings took on special meaning.
The Synod on Synodality was a multiyear, worldwide conversation where Catholics could share concerns and challenges with local church leaders, informing the topics synod participants would eventually discuss in Rome. What’s more, the synod’s voting members included not only bishops but lay Catholics – a first for the church.
Participants arrive for a vigil prayer led by Pope Francis and other religious leaders before the 2023 Synod of Bishops assembly.Isabella Bonotto/Anadolu Agency via Getty Images
The process “pictures the Catholic Church not as a top-down hierarchy but rather as an open conversation,” writes University of Dayton religious studies scholar Daniel Speed Thompson – one in which everyone in the church has a voice and listens to others’ voices.
5. Global dance
In 2024, University of Notre Dame professor David Lantigua had a cup of maté tea with some “porteños,” as people from Buenos Aires are known. They shared a surprising take on the Argentine pope: “a theologian of the tango.”
Pope Francis drinks maté, the national beverage of Argentina, in St. Peter’s Square on his birthday on Dec. 17, 2014.Alberto Pizzoli/AFP via Getty Images
Francis does love the dance – in 2014, thousands of Catholics tangoed in St. Peter’s Square to honor his birthday. But there’s more to it, Lantigua explains. Francis’ vision for the church was “based on relationships of trust and solidarity,” like a pair of dance partners. And part of his task as pope was to “tango” with all the world’s Catholics, carefully navigating culture wars and an increasingly diverse church.
Francis was “less interested in ivory tower theology than the faith of people on the streets,” where Argentina’s beloved dance was born.
This story is a roundup of articles from The Conversation’s archives.Molly Jackson, Religion and Ethics Editor, The Conversation
This article is republished from The Conversation under a Creative Commons license. Read the original article.
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Inglewood, California, is taking a new approach to enhance mobility as plans for an ambitious automated people mover falter. On Tuesday, city officials announced a strategic pivot from the Inglewood Transit Connector’s original vision—a fully automated elevated system—to a more practical solution centered around dedicated bus lanes. This shift aims to bolster transit connections between local hubs and the city’s thriving sports and entertainment district.
Inglewood Transit Project
The revised project intends to transform the urban landscape over the next few years. Residents and visitors can look forward to the rollout of new mobility hubs dedicated solely to buses, separate lanes to ensure efficient transit, expanded bike infrastructure, and improved overall traffic flow. Furthermore, upgrades to walkability are including features designed to accommodate the influx of attendees for events at major venues like SoFi Stadium, YouTube Theater, Intuit Dome, and the Kia Forum.
Originally, the Inglewood Transit Connector sought to seamlessly link the Downtown Inglewood Metro station on the K Line with the rapidly developing sports and entertainment area. However, the ambitious people mover project faced significant challenges. Local officials, community members concerned about business displacement, and prominent figures like U.S. Rep. Maxine Waters voiced their apprehensions, ultimately leading to the project’s cancellation.
This strategic pivot signifies a more pragmatic approach to transit solutions in Inglewood. By focusing on dedicated bus lanes, the city can effectively improve access to its bustling attractions without the complexities and potential disruptions associated with constructing an elevated system.
The transition underscores Inglewood’s commitment to enhancing urban mobility, catering to both the local residents and the increasing number of visitors drawn to its vibrant entertainment scene. As the city embraces this new direction, the focus remains steadfast on creating a more connected, accessible infrastructure that meets the needs of its community.
Inglewood’s dedication to improving transit connections exemplifies a growing trend in urban planning—prioritizing adaptable solutions that can be implemented quickly while still serving the long-term goals of connectivity and sustainability. The dedicated bus lanes, complemented by enhanced bike paths and improved pedestrian walkways, will offer a holistic approach to transportation that can keep pace with Inglewood’s dynamic growth.
As the city moves forward with these changes, all eyes will be on Inglewood to see how this revised plan enhances community connectivity while supporting its vibrant cultural and entertainment district.
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One of two main craters on Alaska’s Mount Spurr, shown in 1991. Earthquake activity suggests the volcano is close to erupting again in 2025.
R.G. McGimsey/Alaska Volcano Observatory/U.S. Geological Survey, CC BYDavid Kitchen, University of Richmond
Volcanoes inspire awe with spectacular eruptions and incandescent rivers of lava, but often their deadliest hazard is what quietly falls from the sky.
When a large volcano erupts, as Mount Spurr appears close to doing about 80 miles from Anchorage, Alaska, it can release enormous volumes of ash. Fine ash can infiltrate the lungs of people and animals who breathe it in, poison crops and disrupt aquatic life. Thick deposits of ash can collapse roofs, cripple utilities and disrupt transport networks.
Ash may lack the visual impact of flowing lava, but as a geologist who studies disasters, I’m aware that ash travels farther, lasts longer and leaves deep scars.
Ash buried cars and buildings after the 1984 eruption of Rabaul in Papua New Guinea.Volcano Hazards Program, U.S. Geological Survey
Volcanic ash: What it is, and why it matters
Volcanic ash forms when viscous magma – molten rock from deep beneath Earth’s surface – erupts, exploding into shards of rock, mineral and glass carried in a near-supersonic stream of hot gas.
Towering clouds of ash rise several miles into the atmosphere, where the ash is captured by high-altitude winds that can carry it hundreds or even thousands of miles.
As the volcanic ash settles back to Earth, it accumulates in layers that typically decrease in thickness with distance from the eruption source. Near the vent, the ash may be several feet deep, but communities farther away may see only a dusting.
When Mount Spurr erupted in 1992, a dark column of ash and gas shot into the atmosphere from the volcano’s Crater Peak vent. Wind patterns determine where the ash will fall.U.S. Geological Survey
Breathing danger: Health risks from ash
Breathing volcanic ash can irritate the throat and lungs, trigger asthma attacks and aggravate chronic respiratory conditions such as COPD.
The finest particles pose the greatest risk because they can penetrate deep into the lungs and cause death by asphyxiation in the worst cases. Mild, short-term symptoms often resolve with rest. However, the long-term consequences of ash exposure can include silicosis, a lung disease and a possible cause of cancer.
The danger increases in dry regions where fallen ash can be kicked up into the air again by wind or human activity.
Risks to pets and livestock
Humans aren’t the only ones at risk. Animals experience similar respiratory symptoms to humans.
Domestic pets can develop respiratory distress, eye inflammation and paw irritation from exposure to ash.
Ash covers sheep in Argentina after the 2011 Puyehue volcanic eruption in Chile.Federico Grosso/U.S. Geological Survey
Livestock face greater dangers. If grazing animals eat volcanic ash, it can damage their teeth, block their intestines and poison them.
During the 2010 Eyjafjallajökull eruption in Iceland, farmers were advised to shelter sheep and cattle because the ash contained fluoride concentrations above the recognized safety threshold of 400 parts per million. Animals that remained exposed became sick and some died.
Harm to crops, soil and water
Soil and crops can also be damaged. Volcanic ash alters the acidity of soil and introduces harmful elements such as arsenic and sulfur into the environment.
While the ash can add nutrients such as potassium and phosphorus that enhance fertility, the immediate impact is mostly harmful.
Ash can smother crops, block sunlight and clog the tiny stomata, or pores, in leaves that allow plants to exchange gases with the atmosphere. It can also introduce toxins that render food unmarketable. Vegetables, fruit trees and vines are particularly vulnerable, but even sturdy cereals and grasses can die if ash remains on leaves or poisons emerging shoots.
Following the 1991 Mount Pinatubo eruption, vast tracts of farmland in central Luzon in the Philippines were rendered unproductive for years due to acidic ash and buried topsoil. If multiple ashfalls occur in a growing season, crop failure becomes a near certainty. It was the cause of a historic famine that followed the eruption of Mount Tambora in 1815.
Ash from a 1953 eruption of Mount Spurr included very fine grains, like powder. The ash cloud reached about 70,000 feet high and left Anchorage under a blanket of ash up to a quarter-inch deep, according to a U.S. Geological Survey report at the time.James St. John via Wikimedia Commons, CC BYElectron microscope images of ash show how sharp the shards are. The top left image of shards from Mount Etna in 2002 is 1 mm across. Top right is an ash particle from Mount St. Helens magnified 200 times. The shards in the lower images are less than 0.064 mm.Volcano Hazards Program, U.S. Geological Survey
Ash can also contaminate surface water by introducing toxins and increasing the water’s acidity. The toxins can leach into groundwater, contaminating wells. Fine ash particles can also settle in waterways and smother aquatic plants and animals. During the 2008 Chaitén eruption in Chile, ash contamination led to widespread fish deaths in the Río Blanco.
Ash can ground airplanes, gum up infrastructure
Ash clouds are extremely dangerous to aircraft. The glassy ash particles melt when sucked into jet turbines, clog fuel systems and can stall engines in midair.
In 1982, British Airways Flight 9 lost power in all four engines after flying through an ash cloud. A similar incident occurred in 1989 to KLM Flight 867 over Alaska. In 2010, Iceland’s Eyjafjallajökull eruption grounded more than 100,000 flights across Europe, disrupting travel for over 10 million passengers and costing the global economy billions of dollars.
Volcanic ash can also wreak havoc on infrastructure by clogging water supplies, short-circuiting electrical systems and collapsing roofs under its weight. It can disrupt transportation, communication, rescue and power networks, as the 1991 eruption of Mount Pinatubo in the Philippines dramatically demonstrated.
What to do during ashfall
During an ashfall event, the most effective strategy to stay safe is to stay indoors as much as possible and avoid inhaling ash particles.
Anyone who must go outside should wear a properly fitted N95 or P2 mask. Cloth masks provide little protection against fine ash. Rainwater tanks, troughs and open wells should be covered and monitored for contamination. Livestock should be moved to clean pastures or given uncontaminated fodder.
The challenges Alaska is facing if Mount Spurr erupts.
To reduce structural damage, ash should be cleared from roofs and gutters promptly, especially before rainfall.
Older adults, children and people who are sick are at greatest risk, particularly those living in poorly ventilated homes. Rural communities that are dependent on agriculture and livestock are disproportionately affected by ashfall, as are low-income people who lack access to clean water, protective masks or safe shelter.
Communities can stay informed about ash risks through official alerts, including those from the Volcanic Ash Advisory Centers, which monitor ash dispersion and issue timely warnings. The International Volcanic Health Hazard Network also offers guidelines on personal protection, emergency planning and ash cleanup.
The long tail of ash
Volcanic ash may fall quietly, but its effects are widespread, persistent and potentially deadly. It poses a chronic threat to health, agriculture, infrastructure and aquatic systems.
Recognizing the risk is a crucial first step to protecting lives. Effective planning and public awareness can further help reduce the damage.
David Kitchen, Associate Professor of Geology, University of Richmond
This article is republished from The Conversation under a Creative Commons license. Read the original article.
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Molly Jackson, Religion and Ethics Editor, The Conversation
This article is republished from The Conversation under a Creative Commons license. Read the original article.
