Rachel Feltman: Happy Monday to all our listeners! for scientific american‘s science fastI’m Rachel Feltman. Welcome to the first science news roundup of 2025. Here’s some news you may have missed last week.
There’s a lot of public health news right now, so I’ll put it at the top.
First, norovirus cases are currently on the rise in several areas of the United States. The Centers for Disease Control and Prevention reports that during the week of Dec. 5, the most recent week for which the center has official statistics, there were 91 cases of norovirus registered by state health departments nationwide. . It may not sound like a big deal, but keep in mind that these are just official reports. Most people have a miserable time when infected with norovirus, but they don’t need to be treated for a “stomach cold.” Additionally, the CDC reported no more than 41 outbreaks in the same week from 2021 to 2024. Norovirus is highly contagious and one of the few pathogens that hand sanitizers cannot kill. Therefore, always wash your hands with soap and water before eating, handling food, or taking medicine, and of course after using the toilet or changing diapers.
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Next, let’s look into avian influenza. Last week, the Louisiana Department of Health reported the first U.S. death from the H5N1 virus, which has infected at least 66 people in the U.S. since early 2024. The deceased became in critical condition after coming into contact with both wild birds and backyard poultry. The Department of Health said the person was over 65 years old and had underlying health conditions, and most cases of H5N1 infection in the United States do not require hospitalization. But even though the current risk is low for most people, that doesn’t mean we don’t have a risk of things changing for the better. We’ll have a longer conversation on Wednesday about the status of H5N1.
Finally, you may have seen headlines about the rise in human metapneumovirus infections in China. There have also been news of infected people in India. But the good news is that this upper and lower respiratory tract virus, called HMPV for short, is not currently a cause for concern in the United States. Unlike the new coronavirus, HMPV has been around for more than 60 years, and many people have some degree of immunity to it. The number of HMPV infections has been steadily increasing in the United States since November, according to CDC data, but the impact currently pales in comparison to both the coronavirus and seasonal influenza. Our advice for HMPV is therefore simple and the same as our advice for other respiratory infections. That means wearing a mask, washing your hands, and staying home if you feel sick.
Speaking of health, last Tuesday the Biden administration announced rules to exclude medical debt from U.S. credit reports. According to the Consumer Financial Protection Bureau, this could erase an estimated $49 billion in debt from the credit reports of about 15 million Americans and boost their credit scores by an average of 20 points. This rule also prevents the confiscation of equipment such as wheelchairs and prosthetic limbs. Several House Republicans oppose the rule and are expected to seek to repeal it under the next administration. The Consumer Data Industry Association, which represents credit reporting agencies, said in a statement that it will work to “protect the credit reporting system and combat the CFPB’s misguided forays into this space.” Approximately 14 million people in the United States have medical debt of $1,000 or more, according to a KFF data analysis. Approximately 3 million Americans, or 1 in 100 adults, have debts of $10,000 or more.
Moving on to the climate, several intense wildfires broke out in Los Angeles last week.
(Clip: (Karen Bass, Mayor of Los Angeles): “Hello, everyone. I want to thank all the leaders for being here today. We will unite our city. We will get through this crisis. And , we will rebuild our city.” Dear Los Angeles, First of all, of course, my heart goes out to the thousands of Angelinos who have been affected by this continuing fire, unfortunately new. There’s a fire…”
I spoke with Andrea Thompson. siam‘s senior news editor for Earth and Environment spoke last Thursday evening about how this all started and where the disaster goes from here.
So, Andrea, can you explain what happened this past week in Los Angeles?
Andrea Thompson: Los Angeles experienced one of the most destructive fires ever seen, and it was the result of several things coming together. One is a big wind event in Santa Ana. This is a common phenomenon in that part of the country at this time of year and occurs with certain weather settings.
So you have an area of high pressure air over what’s called the Great Basin, which is the interior of the West, and then you have an area of low pressure air over Southern California. Air then tries to move from high pressure to low pressure. So the wind moves offshore in that direction. The Great Basin is slightly higher than that elevation, so the air is compressed as it moves down the slope. That means hotter and drier weather. Hotter, drier weather is highly conducive to fires.
As the air descends, it tries to take the path of least resistance. That’s the mountain canyon that actually spans this region. As it pours into these valleys, it picks up speed. So all these factors mean that once a fire starts, it’s primed to spread very quickly. And that’s exactly what happened at this event, and it was very intense. And it happened to coincide with very dry weather.
The region typically has a rainy winter season, and while rain would normally arrive by now to reduce fire danger, this was one of the hottest and driest winter starts ever in Southern California. . So this is the perfect storm for any spark to ignite and turn into a massive fire.
And that’s exactly what happened with the Palisades and Eaton fires in particular. These are wind-driven events, and the winds are so fast that it is virtually impossible to stop them at the height of the wind, and there is nothing firefighters can do to contain the fire at that point. The wind is too strong for helicopters and other aircraft to drop water droplets. The fire is moving too fast for firefighters on the ground to reach the fire.
Feltman: How is this different from wildfires that have been common in the past in California and Los Angeles?
Thompson: Therefore, this type of fire is not uncommon in this region. That’s what the ecosystem in this area evolved into. Because these places are inhabited by far more people than historically existed, their destructive power is extraordinary. When fires broke out in the past when people lived there, we extinguished them. And that suppression means more fuel is available in case a fire breaks out.
This trend is especially noticeable this year. That’s because the previous winter had been two consecutive wet ones, so there was plenty of water to support the growth of many plants. Then came a hot summer and a hot autumn, and all the plants dried up and became as dry as tinder. Whenever there’s a spark, it starts moving.
These are different from those found in forested areas in other parts of California and other parts of the West. Forest fires and wildfires can differ slightly in several ways. The way the fire travels may be slightly different. Effects and smoke types may vary slightly. However, when it comes to the LA Basin, similar fires have occurred in the past. This is the most destructive thing we’ve seen in a while. In fact, the Palisades are the most destructive in the city’s history.
Feltman: What’s the situation in LA right now, Thursday, almost 5pm ET?
Thompson: The main fires, the Palisades and Eaton fires, remain in what is called “zero containment.” That means it’s burning without any boundaries set up by firefighters to stop the fire from spreading.
The wind should pick up again. By Tuesday night, it had declined from its peak. This is part of what allowed firefighters to get to the front of the Sunset Fire. The winds weren’t too bad so we were able to use a helicopter that actually dropped water drops and that really helped stop the fire from progressing a little bit more. Also, the winds had died down, which meant the fire wasn’t spreading as quickly, but it still allowed the embers to come forward from the wind that was there, causing so-called spot fires, which then grew and formed a fire front. I saw it merge and continue downhill.
Firefighters are now trying to get a grip on the blaze and try to contain it to protect as many structures as possible. They are watching for new fires to start because there is always the possibility of new fires starting. The weather is still incredibly dry and very warm.
So basically, they’re actually trying to evacuate before the fire, while the winds aren’t that bad. Even if the wind doesn’t get stronger, it always does, so be prepared for when it gets stronger again. The situation is expected to worsen as it did on Tuesday, but there is still a good chance of another large fire.
Feltman: Andrea, thank you for taking the time to explain.
Listener: Our thoughts are with everyone affected by the fires in and around Los Angeles. Of course, this is a rapidly evolving story, so if you’re looking for more up-to-date information, we recommend checking our latest news sources. Visit sciam.com to see Andrea’s latest coverage of the situation.
Finally, I would like to introduce some great space news. Last Friday, we talked about the search for the mysterious and completely hypothetical Planet Nine in our solar system. But just because Pluto is no longer a full planet doesn’t mean scientists don’t care about it. A new study aims to explain how Pluto and its largest moon Charon started their unique cosmic dance. Instead of the moon orbiting Pluto, Charon and the dwarf planet both orbit the same fixed point between them. The pair is also tidally locked. That is, they always rotate so that the same faces are facing each other, like a pair of ice dancers holding hands and spinning together.
So how did Charon get there? The new study says it was a “kiss and catch.” Basically, the idea is that Charon and Pluto will collide with each other at some point, then spend some time stuck together, and then Pluto’s rotation will push Charon away.
Previous theories primarily focused on a process similar to the formation of our moon, in which collisions melt and mix both bodies. The researchers behind the new study say Pluto and Charon should have behaved differently because they are much smaller than most objects thought to perform that kind of smoothing.
That’s all for this week’s news summary. We’ll talk more about bird flu on Wednesday. And on Friday, we’ll have an interesting conversation about why so many languages say “ouch” the same way.
science fast It is produced by me, Rachel Feltman, Fonda Mwangi, Kelso Harper, Madison Goldberg, and Jeff DelVisio. Emily Murkowski, Shayna Possess, and Aaron Shattuck fact-check the show. Our theme music was composed by Dominic Smith. Subscribe scientific american Check out more latest and in-depth science news.
for scientific american, Rachel Feltman. Have a great week!
