Zika should soon run its course in Latin America.

Within the next couple of years, the epidemic that has battered the region since 2015 will largely be over, researchers estimate in a paper online July 14 in Science.

“If we’re not past the peak already, we’re very close to it,” says study coauthor Neil Ferguson of Imperial College London. After this outbreak winds down, it may be a decade ­— at least — before another large-scale Zika epidemic hits the region.
The new timeline could help vaccine researchers get a jump on future outbreaks, and might make health officials rethink advice to pregnant women trying to avoid Zika-related birth defects. Ferguson’s work also suggests something counterintuitive: Current efforts to kill Zika-carrying mosquitoes might actually make it easier for the virus to reemerge.

“It’s an important and timely analysis,” says infectious disease researcher Oliver Pybus of the University of Oxford. “Policy makers would be wise to read it carefully.”

Brazil reported the first cases of Zika in May 2015. Since then, the mosquito-borne virus has spread to 48 countries. Scientists have now widely accepted Zika as a cause of microcephaly, a devastating birth defect that leaves babies with shrunken heads and brains, as well as other serious problems (SN Online: 6/28/16).

Scientists and health officials have hustled to fight Zika, but they’ve had trouble keeping up. Mosquito-control efforts haven’t helped much, says Ferguson, and a safe and effective vaccine could still be years away. What’s more, advice to postpone pregnancy isn’t always realistic, he says.

Predicting the epidemic’s course could refine current Zika-fighting strategies.
Ferguson and colleagues made a computer simulation of Zika transmission within Latin America, using data from 35 countries that have reported cases. The team factored in such variables as seasonal climate variation, the ease with which Zika jumps from person to mosquito to person, and human travel patterns between countries.

After the current outbreak ends, simulations show that some 30 years could pass before Zika transmission picks up again. Once infected with Zika, people are immune to the virus, Ferguson says, capping an epidemic’s length and buying some time before a resurgence. He can’t say for sure that another major outbreak is still three decades away — but suspects a lull could last at least one decade.

Zika has “been burning through the population,” Ferguson says. “Sooner or later, it starts to run out of people to infect.”

The virus doesn’t need to infect everybody to peter out — just enough to generate herd immunity. At that point, so many people are immune to Zika that it can’t easily spread, protecting those still uninfected.

Killing mosquitoes — a strategy some countries have used to curb Zika’s reach — could actually hinder herd immunity, letting the next epidemic strike sooner, the team’s simulations suggest. With mosquito control that’s only marginally effective, a second wave of Zika hits about five years earlier than with no mosquito control at all, the simulations indicate.

“It makes sense theoretically,” says epidemiologist Mikkel Quam of Umeå University in Sweden. But considering that the cost of herd immunity might be more babies born with birth defects, he says, “any way to reduce infection is worth doing now, even if it means potentially more epidemics in years to come.”

Immunity to Zika could pose problems for vaccine development, Ferguson says. By the time researchers have something that’s safe to use, it will be hard to find a group of people to test it in. “This was a problem at the end of the Ebola epidemic as well,” he says.

Still, Ferguson says it’s an opportunity to think creatively. In the future, for instance, researchers could prequalify trial sites and get clinicians on the ground early, so when (and if) Zika hits somewhere else, say southeast Asia, they’re ready to go.

He also thinks his simulation could help health officials more clearly lay out the risks to pregnant women. Though the epidemic in Latin America will last roughly three years, his team estimates, individual outbreaks within the region can taper off after three to six months.

By tailoring recommendations to different locations, officials could limit the period of time they’re advising women to delay pregnancy.

When a honeybee colony gets hot and bothered, the crisis sets tongues wagging. Middle-aged bees stick their tongues into the mouths of their elders, launching these special drinker bees to go collect water. That’s just one detail uncovered during a new study of how a colony superorganism cools in hot weather.

Using lightbulbs to make heat waves in beehives, researchers have traced how honeybees communicate about collecting water and work together in deploying it as air-conditioning. The tests show just how important water is for protecting a colony from overheating, Thomas Seeley of Cornell University and his colleagues report online July 20 in the Journal of Experimental Biology.
Water collection is an aspect of bee biology that we know little about, says insect physiologist Sue Nicolson of the University of Pretoria in South Africa. Collecting pollen and nectar have gotten more attention, perhaps because honeybees store them. Water mostly gets picked up as needed.

Bees often get as much water as they need in the nectar they sip. But they do need extra water at times, such as during overheating in the center of the nest where eggs and young are coddled. When researchers artificially heated that zone in two colonies confined in a greenhouse, worker bees fought back. They used their wings to fan hot air out of the hive. “You can put your hand in the opening of a hive on a hot day and feel the blast of air that’s being pushed out,” Seeley says. Several hundred bees also moved out of the nest to cluster in a beardlike mass nearby. Their evacuation reduces body heat within the nest and opens up passageways for greater airflow, he says.

The bees also had a Plan C — evaporative cooling. Middle-aged bees inside a hive walked toward the nest entrance to where a small number of elderly bees, less than 1 percent of the colony, hang out and wait until water is needed. Heat by itself doesn’t activate these bees, especially since they’re not in the overheating core. Seeley now proposes that the burst of middle-aged bees’ repeated begging for water by tongue extension eventually sends the water-collecting bees into action. They return carrying some 80 percent of their weight in water. “The water carrier comes in looking really fat, and the water receivers start out looking very skinny,” Seeley says. “Over a minute when the transfer takes place, their forms reverse.” Then the receiving bees go to the hot zone, regurgitate their load of water and use their tongues to spread it over the fevered surfaces.

In a water-deprivation experiment, bees prevented from gathering water could not prevent temperatures from rising dangerously, up to 44° Celsius, in their hive. When researchers permitted water-collector squadrons to tank up again, colonies could control temperatures. Even for multitalented bees, water is necessary for cooling, the researchers conclude.

After a severe heat stress, the researchers noticed some bees with plumped-up abdomens hanging inside the colony. “Sometime they would be lined up like bottles of beer in the refrigerator,” Seeley says. Bottled beverages is what they were, he argues, storing water and remaining available if the coming night proved as water-stressed as the day.

“Honeybees continue to amaze,” says Dennis vanEngelsdorp of the University of Maryland in College Park, who studies bee health. “Even after centuries of study, we have something new.”

Boeing Milestones of Flight Hall
Now open
After two years of renovations, some of the museum’s most cherished artifacts — including the Spirit of St. Louis and an Apollo Lunar Module — are now on display alongside new objects, including a studio model of the Starship Enterprise.

National Air & Space Museum, Washington, D.C.
Pterosaurs: Flight in the Age of Dinosaurs
Through October 2
Fossils, life-size models and a virtual flight lab transport visitors back to the time of these ancient fliers.

Natural History Museum of Los Angeles County
DARPA: Redefining Possible
Through September 5
In this hands-on exhibit, see a humanlike robot, prosthetic arm, robotic exoskeleton and other high-tech innovations developed by the U.S. Defense Advanced Research Projects Agency over the last six decades.

Museum of Science and Industry, Chicago

Exercise may not erase old memories, as some studies in animals have previously suggested.

Running on an exercise wheel doesn’t make rats forget previous trips through an underwater maze, Ashok Shetty and colleagues report August 2 in the Journal of Neuroscience. Exercise or not, four weeks after learning how to find a hidden platform, rats seem to remember the location just fine, the team found.

The results conflict with two earlier papers that show that running triggers memory loss in some rodents by boosting the birth of new brain cells. Making new brain cells rejiggers memory circuits, and that can make it hard for animals to remember what they’ve learned, says Paul Frankland, a neuroscientist at the Hospital for Sick Children in Toronto. He has reported this phenomenon in mice, guinea pigs and degus (SN: 6/14/14, p. 7).
Maybe rats are the exception, he says, “but I’m not convinced.”

In 2014, Frankland and colleagues reported that brain cell genesis clears out fearful memories in three different kinds of rodents. Two years later, Frankland’s team found similar results with spatial memories. After exercising, mice had trouble remembering the location of a hidden platform in a water maze, the team reported in February in Nature Communications. Again, Frankland and colleagues pinned the memory wipeout on brain cell creation — like a chalkboard eraser that brushes away old information. The wipe seemed to clear the way for new memories to form.

Shetty, a neuroscientist at Texas A&M Health Science Center in Temple, wondered if the results held true in rats, too. “Rats are quite different from mice,” he says. “Their biology is similar to humans.”
Using a water maze similar to Frankland’s, Shetty’s team taught two groups of rats how to find a hidden platform in eight training sessions over eight days. Then rats in just one of the groups exercised on a running wheel. Four weeks later, rats in both groups performed the same in the maze test — despite the fact that running rats had 1.5 to 2 times more newly born brain cells in the hippocampus, a skinny strip of tissue that’s thought to help form new memories.
These results and other memory tests “clearly showed that exercise did not interfere with memory recall,” Shetty says. And it’s likely that exercise doesn’t harm human memories either, he says.

Frankland says it’s possible that Shetty’s rats just learned the water maze too well. Shetty’s team trained their rodents for longer than Frankland’s team did, perhaps etching memories more deeply in the brain.

“The stronger the memory is, the harder it is going to be to erase it,” Frankland says.

But he points out that erasing memories isn’t necessarily a bad thing. “People get hung up on this idea,” he says, but actually, clearing out old info from the brain — forgetting — is important. Without some sort of clearance process, “your memory is going to be full of junk.”

Manchester, England, is not the birthplace of graphene — the atom-thin, honeycomb-like layer of carbon known for its wondrous properties and seemingly limitless applications. But the city is the material’s main booster and, according to the University of Manchester, the official Home of Graphene. That’s because it was there that Andre Geim and Kostya Novoselov figured out that you could isolate the elusive material from graphite (the “lead” in pencils) with repeated dabs of sticky tape.
The two-dimensional material also proved to be a peerless electrical conductor and superstrong, earning the two Manchester scientists the 2010 Nobel Prize in physics. So when the city played host to the EuroScience Open Forum conference late last month, it made sense that Geim, graphene and the material’s many evolving applications took center stage. At the local science museum’s new exhibit about graphene, I learned that Geim is the only Nobelist who has also been honored with an Ig Nobel (which has fun celebrating seemingly useless research in science). He contends many are more familiar with his Ig Nobel–winning device to levitate a tiny frog than with his work on graphene.

Notably, graphene comes up in both of the feature stories in this issue, adding some heft, perhaps, to Mancunian claims. In Thomas Sumner’s cover story “Quenching society’s thirst,” about the growing interest in desalination to meet the globe’s escalating need for freshwater, graphene oxide has a potentially starring role. New membranes made from this material may help increase the efficiency of separating salt from water. Cost and efficiency, Sumner reports, remain the biggest obstacles to the widespread use of desalination.

Graphene can serve as analogy and inspiration in physicists’ efforts to create solid metallic hydrogen, another theorized wonder material, which Emily Conover describes in “Chasing a devious metal.” “It’s a high-stakes, high-passion pursuit that sparks dreams of a coveted new material that could unlock enormous technological advances in electronics,” Conover writes. Solid hydrogen, which has been made, takes on a graphenelike structure when squeezed to high pressures. Solid metal hydrogen might be a superconductor at room temperature, an exciting prospect. Despite significant progress, so far no one has been able to create it.

Local celebrity or not, graphene did share the spotlight with other science superstars at the EuroScience meeting. The gene-editing tool CRISPR got lots of attention. In a review of the historic detection of gravitational waves, Sheila Rowan of the University of Glasgow offered a bevy of questions that gravitational astronomy might be able to answer in the coming years: Where and when do black holes form? What does that tell you about the large-scale formation of galaxies? Is general relativity still valid when gravity is very strong (such as near supermassive black holes)? A session on the human microbiome generated even more questions, as scientists described efforts to use microbial species as telltale signs of diseases such as cancer. And a debate about how to prevent food allergies left most agreeing that more data are needed. As answers come in on all of these and many more fascinating topics, you can be sure that Science News will be there to report on them.

COLUMBIA, Mo. — Human babies born via cesarean section miss out on an opportunity to pick up beneficial microbes that other babies get when they take a trip through mom’s vagina. And even though the scientific jury’s still out on whether this is a good idea, some parents have been wiping their C-section babies down with vaginal fluid in the hopes that their newborns might get some of those microbial benefits, Laura Sanders reported earlier this yearover at the Growth Curve blog.

Microbial transfer from mom to offspring happens in a lot of species, but researchers are more familiar with how species that give live birth do this than those that lay eggs, biologist Stacey Weiss of the University of Puget Sound in Tacoma, Wash., noted August 1 at the 53rd Annual Conference of the Animal Behavior Society. Researchers have found that moms can transfer microbes right into the egg itself before it is laid or onto or near the egg after laying.

But Weiss thinks that such microbial transfer might happen through another route — as eggs travel through a female animal’s cloaca. (The cloaca is a combination of genital tract and end of the digestive system found in many invertebrates and most vertebrates, except most mammals.) She and her colleagues have been studying whether striped plateau lizard moms transfer microbes that protect their eggs from pathogens.

“Pathogenic infection is one of the leading causes of egg mortality,” she said. And some studies have proposed that microbes might be able to protect against those infections. None have yet proposed that the source of the microbes could be the cloaca, but this might be a common source since “all vertebrate eggs go through cloacas, and all cloacas have microbes,” she said.

Weiss latched onto the idea that microbes from the cloaca might be important after noticing that when she obtained eggs through dissection, they tended to have a lower survival rate than eggs that were laid. The dissected eggs often succumbed to fungal infections, while the laid eggs did not.

She and her team started by comparing the microbiomes of male and female lizards’ cloacas. “Females are different than males,” she said. Males had more diverse microbial communities in their cloacas. Females were missing whole categories of microbes found in males and had one type that is known to have antifungal activity.

The researchers then compared the microbiomes of eggs that were laid with those that had been dissected out. The team is still waiting on the results of DNA tests that will tell them exactly what kinds of microbes are found on the eggs, but initial results showed that the laid eggs are more likely to have any bacteria at all. “There’s something about going through the cloaca that is increasing bacterial load on these eggshells,” Weiss said. Fungi, though, showed up only on eggs that had been obtained through dissection.
Weiss, her colleagues and some high school students then performed tests in which fungus was applied directly to eggs. They found that laid eggs were able to inhibit fungal growth while dissected eggs were not. So it appears that the mom’s cloaca microbiome may indeed be providing some protection for her offspring.

Weiss said that these results, while still preliminary, may help expand what parental protection of offspring means. In species without direct parental care, transfer of microbes might be an important way that moms and dads help to keep their offspring safe.

Going for walks, playing fetch and now participating in genetic research are just a few things people and their dogs can do together.

Darwin’s Dogs, a citizen science project headquartered at the University of Massachusetts Medical School in Worcester, is looking for good — and bad — dogs to donate DNA. The project aims to uncover genes that govern behavior, including those involved in mental illness in both people and pets.

Looking to dogs for clues about mental illness isn’t as strange as it may seem. Certain breeds are plagued by some of the same diseases and mental health issues that afflict people. Researchers have learned about the genetics of narcolepsy and obsessive compulsive disorder, as well as cancer, blindness and many other ailments from studying purebred dogs. Studies of purebreds are mainly useful when the problem is caused by mutations in a single gene. But most behaviors are the product of interactions between many genes and the environment. A search for those genes can’t be done with a small number of genetically similar dogs. So, Darwin’s Dogs hopes to gather data on a large number of canines, including many breeds and genetically diverse mutts.
Finding behavior-related genes, such as ones that lead dogs to chew up shoes or engage in marathon fetch sessions, may give clues to genes that affect human behavior. “It seemed to me that if we could understand how [changes in DNA] make a dog so excited about chasing a ball, we could learn something about how our brains work and what goes wrong in psychiatric disease,” says project leader Elinor Karlsson.

Karlsson and colleagues launched darwinsdogs.org, inviting people to answer questions about their dogs’ behavior and share their pets’ DNA. More than 7,000 dog owners have already signed up, and the researchers are still recruiting new volunteers.

The process is simple and can be done alone with your dog, or even as a family activity. First, take an online quiz about your canine companion. The quiz is divided into multiple sections. Some sections gather basic information about your dog’s appearance, exercise and eating habits; others ask about simple behaviors, such as whether your dog crosses its front paws when lying down or tilts its head. (Some questions are philosophical puzzles like whether your dog knows it is a dog.) Each question has a comment box in case you want to explain an answer. Plan to spend at least half an hour completing the questionnaire.

Once the questions are answered and the dog is registered, researchers send you a DNA sampling kit that comes with written instructions and an easy-to-follow picture guide. The kit contains a large sterile cotton swab for collecting DNA from your dog’s mouth. (It’s an easy procedure for the human involved, and Sally, the 14-year-old Irish setter “volunteer” Science News sampled, was rather stoic.) Also included is a tape measure for recording your dog’s height, length, nose and collar size. When you’re done, just seal the sample, measurement sheet and consent form inside the return mailer and drop it in a mailbox.

Dog owners don’t need to pay a fee to participate, but they do need patience, Karlsson says. It takes time to analyze DNA, and the researchers can’t say exactly how long it will be before owners (and Science News) learn their dogs’ results. These results will include the dog’s raw genetic data as well as information about the dog’s possible ancestry. Knowing ancestry or particular mutations a dog carries may help veterinarians personalize a dog’s care.
Dog trainers are being enlisted to give owners feedback on their dogs’ personalities and to suggest activities the dogs may enjoy. Karlsson hopes to create a way for impatient owners who are willing to donate money to the project to get their reports back faster.

As of today, antibacterial soaps have a short shelf life. The U.S. Food and Drug Administration has banned soap products containing 19 active ingredients, including the notorious chemical triclosan, marketed as antiseptics.

While the term “antibacterial” suggests to consumers that such soaps prevent the spread of germs, evidence suggests otherwise. After asking companies to submit data on the safety and efficacy of their products back in 2013, the FDA noted in its September 2 final ruling that manufacturers failed to prove that these products were safe to use every day or that they were more effective than plain old soap and water at cutting infectious microbes.

“In fact, some data suggests that antibacterial ingredients may do more harm than good over the long-term,” Janet Woodcock, director of the FDA’s Center for Drug Evaluation and Research, said in a statement.

Triclosan, in particular, has a pretty bad rap. Found in many household products, the chemical ends up everywhere from vegetables to our snot. It’s been associated with exposure to toxic compounds, risk of staph infections and mucking up sewage treatment. Over a decade of damning data had already prompted some companies to remove triclosan from their products. Others will have a year to remove it and other newly banned ingredients from their recipes.

The FDA ban does not include antibacterial hand sanitizers, which the agency is evaluating separately. In the meantime, the FDA recommends using hand sanitizers that are at least 60 percent alcohol, or washing with old-school soap and water.

Live long and prosper
In Science News’ special report on a­ging (SN: 7/23/16, p. 16), writers Laura Sanders, Tina Hesman Saey and Susan Milius explored the latest research — from the evolution of aging in the animal kingdom to scientists’ quest to delay the process in humans’ bodies and minds.

“I would very much like to know how research into aging may benefit people who are middle-aged or elderly now?” asked leftysrule200 in a Reddit Ask Me Anything about the special report. “Is there any research that can result in treatments in the very near future, or are the real-world applications only going to be visible in the distant future?”
Middle-aged and elderly people will be the first to benefit from aging research, Saey says. “A clinical trial using the diabetes drug metformin as an antiaging therapy will begin soon. That drug will be tested on healthy people aged 60 and older,” she says.

Sanders cautions that most antiaging treatments are still a long way off. But various studies in rodents and humans provide potential clues to aging’s secrets. Blood from young rats, for instance, has been shown to rejuvenate the bodies and brains of old rats. Based on those findings, a clinical study in humans is now under way that is looking at the effects of plasma from young donors on the brains of people with Alzheimer’s. “If scientists could pinpoint the compounds that give young blood its power, then they could presumably develop drugs that mimic that process,” Sanders says.
In the meantime, people may be able to slow the effects of aging by leading a healthy lifestyle. Sanders points to a long-term study of middle-aged women in Australia. Women who were more physically active had sharper memories 20 years later, the researchers found. Until proven antiaging treatments are available, “it seems that keeping the body physically active and strong is one of the best ways to keep your brain sharp as you age,” she says.
Dino spills its guts
Tiny tracks discovered in the blackened stomach contents of a 77-million-year-old duck-billed dinosaur fossil suggest gut parasites infected dinosaurs, Meghan Rosen reported in “Parasites wormed way into dino’s gut” (SN: 7/23/16, p. 14).

Online reader Jim Stangle Dvm thought the worms may not have been parasites at all. “It is more likely that the tunnels were formed by a scavenger worm [after the dino had died]. Still I think the findings are way cool!” he wrote.

It’s hard to say definitively whether the burrows were made by parasites or not, says paleontologist Justin Tweet. Scavenger worms could have tunneled through the gut after the dino’s death, but his team found only one type of worm burrow “which suggests that either only one kind of scavenger had access to the carcass,” or “that these burrows were an inside job,” Tweet says.

That’s no moon!
A recently discovered asteroid appears to orbit Earth, but that’s just an illusion. The asteroid orbits the sun, but its constant proximity to Earth makes it the planet’s only known quasisatellite, Christopher Crockett reported in “Say What? Quasi­satellite” (SN: 7/23/16, p. 5).

Reader Mike Lieber wondered if the moon could also be a quasisatellite. “The gravitational attraction of the sun on the moon is twice that of the Earth,” he wrote. “It seems that the apparent looping of the moon around the Earth is also illusory.”

The moon is a true satellite, Crockett says. If the sun were to dis­appear, the moon would continue orbiting Earth. “The moon is within Earth’s ‘Hill sphere,’ the volume of space in which Earth’s gravity is the dominant influence,” he says. “The strength of the gravitational force isn’t as important as by how much it changes from one place to another.” Given the moon’s proximity to our planet, Earth prevails. “The moon orbits Earth and the Earth-moon s­ystem orbits the sun,” he says.

For some dropped foods, the five-second rule is about five seconds too long. Wet foods, such as watermelon, slurp up floor germs almost immediately, scientists report online September 2 in Applied and Environmental Microbiology.

Robyn Miranda and Donald Schaffner of Rutgers University in New Brunswick, N.J., tested gummy candy, watermelon and buttered and unbuttered bread by dropping morsels onto various surfaces coated with Enterobacter aerogenes bacteria. Food was left on each surface — stainless steel, ceramic tile, wood and carpet — for time periods ranging from less than a second to five minutes. Afterward, the researchers measured the amount of E. aerogenes on the food, harmless bacteria that share attachment characteristics with stomach-turning Salmonella.

As expected, longer contact times generally meant more bacteria on the food. But the transfer depended on other factors, too. Carpet, for instance, was less likely to transfer germs than the other surfaces. Gummy candies, particularly those on carpet, stayed relatively clean. But juicy watermelon quickly picked up lots of bacteria from all surfaces in less than a second. These complexities, the authors write, mean that the five-second rule is probably a rule worth dropping.