Noelia Silva del Rio, University of California, Davis; Richard V. Pereira, University of California, Davis; Robert B. Moeller, University of California, Davis; Terry W. Lehenbauer, University of California, Davis, and Todd Cornish, University of California, Davis

The discovery of viral fragments of avian flu virus in milk sold in U.S. stores suggests that the H5N1 virus may be more widespread in U.S. dairy cattle than previously realized.

The Food and Drug Administration was quick to stress on April 24, 2024, that it believes the commercial milk supply is safe. However, highly pathogenic avian influenza virus can make cows sick, and the flu virus's presence in herds in several states and now new federal restrictions on the movement of dairy cows between states are putting economic pressure on farmers.

Five experts in infectious diseases in cattle from the University of California, Davis – Noelia Silva del Rio, Terry Lehenbauer, Richard Pereira, Robert Moeller and Todd Cornish – explain what the test results mean, how bird flu can spread to cattle and the impact on the industry.

What are viral fragments of avian flu, and can they pose risks to people?

It's crucial to understand that the presence of viral fragments of H5N1 doesn't indicate the presence of intact virus particles that could cause disease.

The commercial milk supply maintains safety through two critical measures:

• First, milk sourced from sick animals is promptly diverted or disposed of, ensuring it does not enter the food chain.

• Second, all milk at grocery stores is heat treated to reduce pathogen load to safe levels, mainly by pasteurization. Pasteurization has been shown to effectively inactivate H5N1 in eggs, and that process occurs at a lower temperature than is used for milk.

The viral fragments were detected using quantitative polymerase chain reaction testing, which is known for its exceptional sensitivity in detecting even trace amounts of viral genetic material. These fragments are only evidence that the virus was present in the milk. They aren't evidence that the virus is biologically active.

To evaluate whether the presence of the viral fragments corresponds to a virus with the capacity to replicate and cause disease, a different testing approach is necessary. Tests such as embryonated egg viability studies allow scientists to assess the virus's ability to replicate by injecting a sample into an embryonated chicken egg. That type of testing is underway.

On April 24, 2024, the FDA said it had found no reason to change its assessment that the U.S. milk supply is safe. The agency does strongly advise against consuming raw milk and products derived from it because of its inherent risks of contamination with harmful pathogens, including avian flu viruses.

How does an avian flu virus get into cow's milk?

Currently, cows confirmed to have H5N1 have different symptoms than the typical flu-like symptoms observed in birds.

Abnormal milk and mastitis, an inflammatory response to infection, are common. While there is speculation that other bodily secretions, such as saliva, respiratory fluids, urine or feces, may also harbor the virus, that has yet to be confirmed.

How waterfowl or other birds transmitted H5N1 to cattle is still under investigation. In 2015, an outbreak of highly pathogenic avian influenza in commercial poultry farms reached its peak in April and May, the same time birds migrated north. Birds can shed the virus through their oral, nasal, urine and fecal secretions. So the virus could potentially be transmitted through direct contact, ingesting contaminated feed or water, or inhaling the virus.

Infected dairy cows can shed the virus in milk, and they likely can transmit it to other cows, but that still needs to be proven.

Contagious pathogens that cause mastitis can be transmitted through milking equipment or contaminated milker's gloves. Ongoing research will help determine whether this is also a potential transmission route for H5N1, and if so, what makes the virus thrive on mammary tissue.

If H5N1 is found to be widespread in milk, what risks can that pose for the dairy industry?

For the dairy industry, infection of cattle with H5N1 avian influenza virus creates challenges at two levels.

The overriding concern is always for the safety and healthfulness of milk and dairy products.

Existing state and federal regulations and industry practices require sick cows or cows with abnormal milk to be segregated so that their milk does not enter the food supply. Proper pasteurization should kill the virus so that it cannot cause infection.

The American Association of Bovine Practitioners has also developed biosecurity guidelines for H5N1, focusing on key practices. These include minimizing wild birds' contact with cattle and their environment, managing the movement of cattle between farms, isolating affected animals, avoiding feeding unpasteurized (raw) colostrum or milk to calves and other mammals, and ensuring the use of protective personal equipment for animal caretakers.

The other major concern is for the health of the dairy herd and the people who take care of the dairy cattle. A farm worker who handled dairy cows contracted H5N1 in Texas in March 2024, but such cases are rare.

No vaccines or specific therapies are available for avian influenza infections in dairy cattle. But following good sanitation and biosecurity practices for both people and cows will help to reduce risk of exposure and spread of the avian influenza virus among dairy cattle.

For cows that get the virus, providing supportive care, including fluids and fever reducers as needed, can help them get through the illness, which can also cause loss of appetite and affect their milk production.

Dairy farms facing an outbreak will have economic losses from caring for sick animals and the temporary reduction in milk sales. Approximately 5% to 20% of the animals in the affected herds have become ill, according to early estimates. Affected animals typically recover within 10 to 20 days.

At least 21 states have restricted importing dairy cattle to prevent the virus's spread, and the federal government announced it will require that lactating dairy cattle be tested before they can be moved between states starting April 29, 2024. While the overall impact on U.S. milk production is projected to be minor on an annual basis, it could lead to short-lived supply disruptions.

How worried should people be about avian flu?

The federal government's monitoring and food safety measures, along with pasteurization, provide important safeguards to protect the public from potential exposure to avian influenza virus through the food chain.

Drinking raw milk, however, does represent a risk for exposure to multiple diseases, including H5N1. This is why the FDA and Centers for Disease Control and Prevention strongly recommend drinking only pasteurized milk and dairy products.

Noelia Silva del Rio, Associate Specialist in Cooperative Extension, Production Medicine and Food Safety, University of California, Davis; Richard V. Pereira, Associate Professor of Veterinary Medicine and Associate Agronomist, University of California, Davis; Robert B. Moeller, Professor of Veterinary Medicine, University of California, Davis; Terry W. Lehenbauer, Professor of Veterinary Medicine, University of California, Davis, and Todd Cornish, Professor of Veterinary Medicine, University of California, Davis

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Chris Impey, University of Arizona

A critical NASA mission in the search for life beyond Earth, Mars Sample Return, is in trouble. Its budget has ballooned from US$5 billion to over $11 billion, and the sample return date may slip from the end of this decade to 2040.

The mission would be the first to try to return rock samples from Mars to Earth so scientists can analyze them for signs of past life.

NASA Administrator Bill Nelson said during a press conference on April 15, 2024, that the mission as currently conceived is too expensive and too slow. NASA gave private companies a month to submit proposals for bringing the samples back in a quicker and more affordable way.

As an astronomer who studies cosmology and has written a book about early missions to Mars, I've been watching the sample return saga play out. Mars is the nearest and best place to search for life beyond Earth, and if this ambitious NASA mission unraveled, scientists would lose their chance to learn much more about the red planet.

The habitability of Mars

The first NASA missions to reach the surface of Mars in 1976 revealed the planet as a frigid desert, uninhabitable without a thick atmosphere to shield life from the Sun's ultraviolet radiation. But studies conducted over the past decade suggest that the planet may have been much warmer and wetter several billion years ago.

The Curiosity and Perseverance rovers have each shown that the planet's early environment was suitable for microbial life.

They found the chemical building blocks of life and signs of surface water in the distant past. Curiosity, which landed on Mars in 2012, is still active; its twin, Perseverance, which landed on Mars in 2021, will play a crucial role in the sample return mission.

Why astronomers want Mars samples

The first time NASA looked for life in a Mars rock was in 1996. Scientists claimed they had discovered microscopic fossils of bacteria in the Martian meteorite ALH84001. This meteorite is a piece of Mars that landed in Antarctica 13,000 years ago and was recovered in 1984. Scientists disagreed over whether the meteorite really had ever harbored biology, and today most scientists agree that there's not enough evidence to say that the rock contains fossils.

Several hundred Martian meteorites have been found on Earth in the past 40 years. They're free samples that fell to Earth, so while it might seem intuitive to study them, scientists can't tell where on Mars these meteorites originated. Also, they were blasted off the planet's surface by impacts, and those violent events could have easily destroyed or altered subtle evidence of life in the rock.

There's no substitute for bringing back samples from a region known to have been hospitable to life in the past. As a result, the agency is facing a price tag of $700 million per ounce, making these samples the most expensive material ever gathered.

A compelling and complex mission

Bringing Mars rocks back to Earth is the most challenging mission NASA has ever attempted, and the first stage has already started.

Perseverance has collected over two dozen rock and soil samples, depositing them on the floor of the Jezero Crater, a region that was probably once flooded with water and could have harbored life. The rover inserts the samples in containers the size of test tubes. Once the rover fills all the sample tubes, it will gather them and bring them to the spot where NASA's Sample Retrieval Lander will land. The Sample Retrieval Lander includes a rocket to get the samples into orbit around Mars.

The European Space Agency has designed an Earth Return Orbiter, which will rendezvous with the rocket in orbit and capture the basketball-sized sample container. The samples will then be automatically sealed into a biocontainment system and transferred to an Earth entry capsule, which is part of the Earth Return Orbiter. After the long trip home, the entry capsule will parachute to the Earth's surface.

The complex choreography of this mission, which involves a rover, a lander, a rocket, an orbiter and the coordination of two space agencies, is unprecedented. It's the culprit behind the ballooning budget and the lengthy timeline.

Sample return breaks the bank

Mars Sample Return has blown a hole in NASA's budget, which threatens other missions that need funding.

The NASA center behind the mission, the Jet Propulsion Laboratory, just laid off over 500 employees. It's likely that Mars Sample Return's budget partly caused the layoffs, but they also came down to the Jet Propulsion Laboratory having an overfull plate of planetary missions and suffering budget cuts.

Within the past year, an independent review board report and a report from the NASA Office of Inspector General raised deep concerns about the viability of the sample return mission. These reports described the mission's design as overly complex and noted issues such as inflation, supply chain problems and unrealistic costs and schedule estimates.

NASA is also feeling the heat from Congress. For fiscal year 2024, the Senate Appropriations Committee cut NASA's planetary science budget by over half a billion dollars. If NASA can't keep a lid on the costs, the mission might even get canceled.

Thinking out of the box

Faced with these challenges, NASA has put out a call for innovative designs from private industry, with a goal of shrinking the mission's cost and complexity. Proposals are due by May 17, which is an extremely tight timeline for such a challenging design effort. And it'll be hard for private companies to improve on the plan that experts at the Jet Propulsion Laboratory had over a decade to put together.

An important potential player in this situation is the commercial space company SpaceX. NASA is already partnering with SpaceX on America's return to the Moon. For the Artemis III mission, SpaceX will attempt to land humans on the Moon for the first time in more than 50 years.

However, the massive Starship rocket that SpaceX will use for Artemis has had only three test flights and needs a lot more development before NASA will trust it with a human cargo.

In principle, a Starship rocket could bring back a large payload of Mars rocks in a single two-year mission and at far lower cost. But Starship comes with great risks and uncertainties. It's not clear whether that rocket could return the samples that Perseverance has already gathered.

Starship uses a launchpad, and it would need to be refueled for a return journey. But there's no launchpad or fueling station at the Jezero Crater. Starship is designed to carry people, but if astronauts go to Mars to collect the samples, SpaceX will need a Starship rocket that's even bigger than the one it has tested so far.

Sending astronauts also carries extra risk and cost, and a strategy of using people might end up more complicated than NASA's current plan.

With all these pressures and constraints, NASA has chosen to see whether the private sector can come up with a winning solution. We'll know the answer next month.

Chris Impey, University Distinguished Professor of Astronomy, University of Arizona

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Doug Cowen, Penn State

About a trillion tiny particles called neutrinos pass through you every second. Created during the Big Bang, these “relic” neutrinos exist throughout the entire universe, but they can't harm you. In fact, only one of them is likely to lightly tap an atom in your body in your entire lifetime.

Most neutrinos produced by objects such as black holes have much more energy than the relic neutrinos floating through space. While much rarer, these energetic neutrinos are more likely to crash into something and create a signal that physicists like me can detect. But to detect them, neutrino physicists have had to build very large experiments.

IceCube, one such experiment, documented an especially rare type of particularly energetic astrophysical neutrino in a study published in April 2024. These energetic neutrinos often masquerade as other, more common types of neutrino. But for the first time, my colleagues and I managed to detect them, pulling out a few from almost 10 years of data.

Their presence puts researchers like me one step closer to unraveling the mystery of how highly energetic particles like astrophysical neutrinos are produced in the first place.

IceCube observatory

The IceCube Neutrino Observatory is the 800-pound gorilla of large neutrino experiments. It has about 5,000 sensors that have peered intently at a gigaton of ice under the South Pole for over a decade. When a neutrino collides with an atom in the ice, it produces a ball of light that the sensors record.

IceCube has detected neutrinos created in several places, such as the Earth's atmosphere, the center of the Milky Way galaxy and black holes in other galaxies many light-years away.

But the tau neutrino, one type of particularly energetic neutrino, has eluded IceCube – until now.

Neutrino flavors

Neutrinos come in three different types, which physicists call flavors. Each flavor leaves a distinct imprint on a detector like IceCube.

When a neutrino bangs into another particle, it usually produces a charged particle that corresponds with its flavor. A muon neutrino produces a muon, an electron neutrino produces an electron, and a tau neutrino produces a tau.

Neutrinos with a muon flavor have the most distinctive signature, so my colleagues and I in the IceCube collaboration naturally searched for those first. The muon emitted from a muon neutrino collision will travel through hundreds of meters of ice, making a long track of detectable light, before it decays. This track allows researchers to trace the neutrino's origin.

The team next looked at electron neutrinos, whose interactions produce a roughly spherical ball of light. The electron produced by an electron neutrino collision never decays, and it bangs into every particle in the ice it comes near. This interaction leaves an expanding ball of light in its wake before the electron finally comes to rest.

Since the electron neutrino's direction is very hard to discern by eye, IceCube physicists applied machine learning techniques to point back to where the electron neutrinos might have been created. These techniques employ sophisticated computational resources and tune millions of parameters to separate neutrino signals from all known backgrounds.

The third flavor of neutrino, the tau neutrino, is the chameleon of the trio. One tau neutrino can appear as a track of light, while the next can appear as a ball. The tau particle created in the collision travels for a tiny fraction of a second before it decays, and when it does decay it usually produces a ball of light.

Those tau neutrinos create two balls of light, one where they initially bang into something and create a tau, and one where the tau itself decays. Most of the time, the tau particle decays after traveling only a very short distance, making the two balls of light overlap so much that they are indistinguishable from a single ball.

But at higher energies, the emitted tau particle can travel tens of meters, resulting in two balls of light separate from one another. Physicists armed with those machine learning techniques can see through this to find the needle in the haystack.

Energetic tau neutrinos

With these computational tools, the team managed to extract seven strong candidate tau neutrinos from about 10 years of data. These taus had higher energies than even the most powerful particle accelerators on Earth, which means they must be from astrophysical sources, such as black holes.

This data confirms IceCube's earlier discovery of astrophysical neutrinos, and they confirm a hint that IceCube previously picked up of astrophysical tau neutrinos.

These results also suggest that even at the highest energies and over vast distances, neutrinos behave in much the same way as they do at lower energies.

In particular, the detection of astrophysical tau neutrinos confirms that energetic neutrinos from distant sources change flavor, or oscillate. Neutrinos at much lower energies traveling much shorter distances also oscillate in the same way.

As IceCube and other neutrino experiments gather more data, and scientists get better at distinguishing the three neutrino flavors, researchers will eventually be able to guess how neutrinos that come from black holes are produced. We also want to find out whether the space between Earth and these distant astrophysical neutrino accelerators treats particles differently depending on their mass.

There will always be fewer energetic tau neutrinos and their muon and electron cousins compared with the more common neutrinos that come from the Big Bang. But there are enough out there to help scientists like me search for the most powerful neutrino emitters in the universe and study the limitless space in between.

Doug Cowen, Professor of Physics and Professor of Astronomy and Astrophysics, Penn State

This article is republished from The Conversation under a Creative Commons license. Read the original article.