Gene-editing tools heralded as hope for fighting invader rats, malarial mosquitoes and other scourges may be too powerful to use in their current form, two new papers warn.

Standard forms of CRISPR gene drives, as the tools are called, can make tweaked DNA race through a population so easily that a small number of stray animals or plants could spread it to new territory, predicts a computer simulation released November 16 at bioRxiv.org. Such an event would have unknown, potentially damaging, ramifications, says a PLOS Biology paper released the same day.
“We need to get out of the ivory tower and have this discussion in the open, because ecological engineering will affect everyone living in the area,” says Kevin Esvelt of MIT, a coauthor of both papers who studies genetic solutions to ecological problems. What’s a pest in one place may be valued in another, so getting consent to use a gene drive could mean consulting people across a species’s whole range, be it several nations or continents.

Researchers have constructed this kind of drive in yeast, a fruit fly and several mosquitoes, but none of the tools have been deployed yet in the wild (SN: 12/12/15, p. 16). Meanwhile, some researchers are already working to add brakes or off-switches into a new generation of gene drives.

The major concern is that current gene drives “are probably too powerful for us to seriously consider deploying in conservation,” says geneticist Neil Gemmell of the University of Otago in Dunedin, New Zealand. Gemmell is a coauthor of the PLOS Biology paper.
This opinion could prove especially controversial in New Zealand. In 2016, the government resolved to protect the nation’s imperiled biodiversity by exterminating invader rats, stoats and possums that are wreaking havoc on native species. Gene drives just might make that possible.

Though warning of perils, the researchers also propose some solutions. A weaker system, which Esvelt calls a daisy drive, splits up components of the drive called guide RNAs. These guide RNAs direct the gene-editing machinery to its DNA target, where molecular scissors then snip and swap genetic material. As genes get inherited or not in the chancy jumbling of sexual reproduction, descendants in later generations become less likely to inherit all the spaced-apart pieces needed to operate the gene drive.

Esvelt’s lab is working to create a daisy drive in two kinds of nematode worms and is looking at other species as well. Other labs are now working on tamer gene drives, too.

Anthony A. James of the University of California, Irvine says that the disease-carrying Anopheles mosquito species that he and his colleagues have equipped with gene drives are self-limiting. When females end up with two of the genes he’s inserting, they don’t “survive very well after they have fed on blood.” Researchers are now raising these mosquitoes to see whether the genes spread and then dwindle away. “We don’t need our genes to last forever,” James says, “only long enough to contribute to getting rid of malaria.”

Another lab’s current version of disease-fighter mosquitoes already has a touch of the daisy. Aedes aegypti mosquitoes engineered with some built-in parts of the gene editor have their guide RNA split into two parts and put on different chromosomes, says molecular biologist Omar Akbari of the University of California, San Diego. Pictures of many weird mosquitoes created this way — all yellow or with three eyes or forked wings — attest to the fact that the drive system works. Akbari’s research appears November 14 in the Proceedings of the National Academy of Sciences.

Akbari is not very worried about the risk of accidentally wiping out disease-carrying mosquitoes. “A thousand children die every day,” he says. It would be unethical not to use a tool that could lessen the loss, he says.

He does recognize that the case for caution could be different for other species. “A lot of pet owners would be sad,” he says, if a gene drive went wrong and escaped worldwide during some future attempt to rid, say, Australia of its terribly destructive feral cats.

Sickness makes some corals lose their glow.

Disease reduces a coral’s overall fluorescence even before any sign of the infection is visible to the naked eye, a new study finds. An imaging technique that illuminates the change could help with efforts to better monitor coral health, researchers report November 6 in Scientific Reports.

Many corals naturally produce fluorescent proteins that glow in a wavelength of light that human eyes can’t see in natural light. Previous studies have shown that heat stress and wounding, among others stressors, can affect coral fluorescence, but the new study is the first to look at the relationship between fluorescence and infectious disease.
Jamie Caldwell, a disease ecologist now at Stanford University, and colleagues used a technique called live-imaging laser scanning confocal microscopy to compare fluorescence in living fragments of healthy and diseased Montipora capitata coral. The reef coral, common in Hawaii, fluoresces in red and cyan, and can contract a bacterial infection called Montipora white syndrome, which causes coral lesions and tissue loss.

The diseased bits looked healthy at the macroscopic level, but under the researchers’ microscope, the sick coral’s pallid complexion was pronounced. Computer analyses of the microscopy images quantified the lost glow (red is the total area of fluorescence, black regions are where fluorescence was lost, and white lines indicate edges between the two zones). Among the samples studied, healthy coral had on average 1.2 times as much fluorescence area as diseased fragments. Diseased coral had disorganized and fragmented patterns of fluorescence — similar to a forest that has been logged extensively, the researchers found.
Such research “is transformative in our struggle to visualize the dance between pathogen attack and host response in the initial attack,” says Drew Harvell, a disease ecologist at Cornell University.
Many coral diseases appear to be increasing around the world, even when accounting for increased research effort, Caldwell says. Along with bleaching events and pollution, disease is considered one of the major contributors to reef declines globally. The new technique could be used for other coral species and diseases, she says.

Magnetic poles are seemingly inseparable: Slice a magnet in half, and you get two smaller magnets, each with its own north and south poles. But exotic magnetic particles that flout this rule may be lurking undetected, some physicists suspect.

The hunt is in full swing for these hypothetical particles known as magnetic monopoles — which possess a lone north or south pole. Now, two groups of researchers have further winnowed down the particles’ possible masses and characteristics, using data from particle accelerators and the corpses of stars.
There’s good reason to suspect magnetic monopoles are out there, some physicists suggest. The particles’ existence would explain why electric charge is quantized — why it always seems to come in integer multiples of the charge of an electron instead of a continuous range of values. As a result, magnetic monopoles are popular. “A lot of people think they should exist,” says James Pinfold, a particle physicist at the University of Alberta in Edmonton, Canada.

If even a single magnetic monopole were detected, the discovery would rejigger the foundations of physics. The equations governing electricity and magnetism are mirror images of one another, but there’s one major difference between the two phenomena. Protons and electrons carry positive and negative electric charges, respectively, but no known particle has a magnetic charge. A magnetic monopole would be the first, and if one were discovered, electricity and magnetism would finally be on equal footing.

For decades, scientists have searched fruitlessly for magnetic monopoles. Recent work at the Large Hadron Collider, located at the particle physics lab CERN in Geneva, has reinvigorated the search. Magnetic monopoles might be produced there as protons slam together at record-high energies of 13 trillion electron volts.

Unfortunately, the latest search by Pinfold and collaborators with the Monopole and Exotics Detector at the LHC, or MoEDAL (pronounced “medal”), found no magnetic monopoles, despite analyzing six times the data as the project’s previous pursuits. Still, the new research has set some of the most stringent constraints yet on how easily the hypothetical particles may interact with matter, the MoEDAL collaboration reports December 28 at arXiv.org.
Magnetic monopoles may also dwell where magnetic fields are extraordinarily strong and temperatures are high. Under these conditions, pairs of monopoles might form spontaneously. Such extreme environments can be found around a special kind of dead star known as a magnetar, and in the aftermath of collisions of heavy atomic nuclei in particle accelerators. By studying these two scenarios, physicists Arttu Rajantie and Oliver Gould, both of Imperial College London, put new constraints on monopoles’ masses, the researchers report in the Dec. 15 Physical Review Letters.

If magnetic monopoles had relatively small masses, the particles would sap the strength of magnetars’ magnetic fields. That fact suggests that the particles must be more massive than about 0.3 billion electron volts — about a third the mass of a proton — the researchers calculate. That estimate depends on another unknown property of monopoles, the strength of their magnetic charge. The particles have a minimum possible magnetic charge. A magnetic charge larger than this baseline value would correspond to a minimum mass greater than 0.3 billion electron volts.

For a monopole with twice the minimum charge, Rajantie and Gould determined that magnetic monopoles must be more massive than about 10 billion electron volts, going by data from collisions of lead nuclei in the Super Proton Synchrotron, a smaller accelerator at CERN. Studying similar collisions of lead nuclei in the LHC could improve this estimate, due to the LHC’s higher collision energies.

While other experiments have set higher monopole mass limits than the new estimates, those analyses relied on questionable theoretical assumptions, Rajantie says. “These are currently the strongest bounds on the masses of magnetic monopoles that don’t rely on assumptions” about how the particles are created, he says.

The results are “very exciting,” says theoretical physicist Kimball Milton of the University of Oklahoma in Norman, who was not involved with the research. Of course, he adds, it’s “not as exciting as if somebody actually found a magnetic monopole.”

Even if monopoles do exist, the particles might be so heavy that they can’t be produced by accelerators or cosmic processes. The only magnetic monopoles in the universe might be remnants of the Big Bang. A future incarnation of MoEDAL, located on a mountaintop instead of in an accelerator’s cavern, could look for such magnetic monopoles that sprinkle down on Earth from space, Pinfold says.

The physics behind a weird electrical phenomenon — glowing orbs of lightning — may be mimicked by something even stranger. A magnetic structure proposed for the natural oddity known as ball lightning makes an appearance in a newfound variety of a knotlike entity called a skyrmion, a team of scientists reports.

Typically observed during thunderstorms, ball lightning is poorly understood. Anecdotal reports describe eerily glowing spheres that float through the air for several seconds before fading (SN: 2/9/02, p. 87). That’s much longer than standard lightning strikes, which last tens of microseconds, and researchers are still struggling to explain how the fireballs persist.
One theory, proposed in the 1990s, suggests that ball lightning is a plasma held together by magnetic fields arranged in rings that link together into a knot. “Because it’s linked up in this tight way, it can’t really fall apart,” says physicist David Hall of Amherst College in Massachusetts. “That could provide a reason why ball lightning survives as long as it does.”
Now, Hall and colleagues have created an analog of such linked magnetic fields in a seemingly unrelated type of knotted structure, a skyrmion. Found in a variety of substances — from thin films of magnetic materials to liquid crystals — skyrmions are a kind of disturbance within matter
( SN: 2/17/18, p. 18 ). The objects can move like independent particles , shifting from place to place within a material while maintaining their knotted configuration ( SN: 10/18/14, p. 22 ). And like a tight knot in a thread, skyrmions are difficult to undo, making them relatively stable structures.
Hall and colleagues created their skyrmion in a state of matter called a Bose-Einstein condensate, composed of atoms cooled to a temperature so low that they all take on the same quantum state and begin acting as if they are one unified entity (SN: 10/13/01, p. 230). The atoms that make up the Bose-Einstein condensate each have a quantum property called spin, which makes them behave like tiny magnets.

When the scientists switched on a specially designed magnetic field, the spins arranged into a twisting structure of loops, knotting up into a configuration known as a Shankar skyrmion. That arrangement was predicted theoretically about 40 years ago, but not seen in the real world until now. While skyrmions found in thin magnetic materials are two-dimensional whirls, the new skyrmion is a 3-D beast, the researchers report March 2 in Science Advances.

Within the condensate, the spins produced something analogous to a magnetic field: The condensate behaved as if it were a charged particle being pushed around by a magnetic field when in reality no such magnetic field existed. Like the skyrmion itself, the scientists realized, the imitation magnetic field was knotted, and it matched the interlinked rings of magnetic fields proposed for ball lightning.

Eventually, studying 3-D knotted magnetic fields like those potentially present in ball lightning might help scientists devise better ways to control plasmas within future fusion reactors for generating power, the researchers suggest.

The creation of knotted structures in Bose-Einstein condensates is in its infancy, and such efforts are “very welcomed” says physicist Egor Babaev of KTH Royal Institute of Technology in Stockholm, who was not involved with the research. “People are just starting to scratch the surface of these objects.”

If signals from an alien civilization ever reach Earth, odds are the aliens will already be dead.

In an effort to update the 1961 Drake Equation, which estimates the number of detectable, intelligent civilizations in the Milky Way, physicist Claudio Grimaldi and colleagues calculated the area of the galaxy that should be filled with alien signals at a given time (SN Online: 11/1/09).

The team, which includes Frank Drake (now a professor emeritus at the SETI Institute in Mountain View, Calif., and the University of California, Santa Cruz), assumed technologically savvy civilizations are born and die at a constant rate. When a civilization dies out and stops broadcasting, the signals it had sent continue traveling like concentric ripples on a pond. Part of the Milky Way should be filled with these ghost signals.
If the civilization lasted less than 100,000 years — the time it takes light to cross the galaxy — then the odds of the signals reaching Earth while the civilization is still broadcasting are vanishingly small, the researchers report February 27 at arXiv.org. Humans, for example, have been transmitting radio waves for only about 80 years, so our radio waves cover less than 0.001 percent of the Milky Way.

“If the civilization emitted from the other side of the galaxy, when the signal arrives here, the civilization will already be gone,” says Grimaldi, of the Federal Polytechnical School of Lausanne in Switzerland.

Surprisingly, the team also calculated that the average number of E.T. signals crossing Earth at a given time should equal the number of civilizations currently transmitting — even if the civilizations we hear from aren’t the same ones presently broadcasting. Grimaldi is now working on a paper about what it means that we’ve found none so far.

THE WOODLANDS, Texas — It’s been six months since NASA’s Cassini spacecraft plunged to its doom in the atmosphere of Saturn, but scientists didn’t spend much time mourning. They got busy, analyzing the spacecraft’s final data.

The Cassini mission ended September 15, 2017, after more than 13 years orbiting Saturn (SN Online: 9/15/17). The spacecraft’s final 22 orbits, dubbed the Grand Finale, sent Cassini into the potentially dangerous region between the gas giant and its rings, and its final orbit sent it directly into Saturn’s atmosphere.
That perspective helped solve mysteries about the planet and its moons that could not be tackled any other way, scientists said March 19 at the Lunar and Planetary Science Conference in The Woodlands, Texas.

“In so many ways, the Grand Finale orbits provided information that was totally unexpected,” said Cassini project scientist Linda Spilker of NASA’s Jet Propulsion Laboratory in Pasadena, Calif. “So many of our models were not correct.”

Here are five things we now know and a few outstanding mysteries.

1. Saturn’s clouds go deep
   Those final daredevil orbits allowed Cassini to measure the gravity of Saturn and its rings independent of one another. Looking at the planet’s gravity field alone revealed that the swirling bands of clouds penetrate much deeper into the planet than expected.

Astronomers this month announced a similar discovery for an even larger gas giant, reporting that the Juno spacecraft, which is orbiting Jupiter, had found that the planet’s rotating cloud belts reach roughly 3,000 kilometers below the top of the atmosphere.

Saturn’s clouds reach a few times deeper than that. “This was an astonishing result,” Spilker said.

“People used to think that maybe Saturn was just a slightly smaller version of Jupiter, but it’s evident that that’s not the case,” says planetary scientist Paul Schenk of the Lunar and Planetary Institute in Houston, who was not involved in the gravity measurements. The difference speaks to how diverse planets are, he says. “Every place you look, everywhere we’ve been to, it’s just been so dramatically different and unique.”

2. Ring rain is eroding the innermost ring
   Grains of ice from the rings are raining down into Saturn’s atmosphere, Cassini’s final orbits confirmed. This “ring rain” idea has been suggested since the 1980s, but only by tasting the atmosphere and directly sampling the space between Saturn and the rings could Cassini confirm the rains are real.

In its last five full orbits, Cassini found a zoo of organic molecules in and just above Saturn’s atmosphere, said planetary scientist Kelly Miller of the Southwest Research Institute in San Antonio. The spacecraft found a lot of water, which wasn’t surprising — water makes up about 90 percent of the rings. But there were also a lot of hydrocarbons similar to propane, plus some methane and sulfur-bearing molecules.

The types of molecules became less well-mixed as the spacecraft looked deeper into Saturn’s atmosphere, which is what would happen if the particles came from the rings and sank at different speeds. The researchers think this material is especially raining from Saturn’s D ring, the thin innermost ring. Other Cassini data suggest this ring is losing mass.

“The D ring is slowly being eroded away and going into the planet,” Spilker said.

3. Organics could explain mysterious ring hues
   The organics in the ring rain could solve a debate about why Saturn’s rings appear reddish in some spots.

“We’ve had this debate going on for a couple of years now — are they red because of good old-fashioned rust like Mars, or because of the same kinds of organic materials … that make carrots and tomatoes and watermelon red?” said planetary scientist Jeff Cuzzi of NASA’s Ames Research Center in Moffett Field, Calif. “To me, this answers the question of what makes the rings red: It’s organics.”

It’s still not clear where the organics come from, though. They could be created within the rings, or they could come from cosmic dust from the tails of comets. Miller and her colleagues are comparing the ring rain molecules with data on comet 67P, which the Rosetta spacecraft observed, to see how well they match up (SN: 11/11/17, p. 32).

4. Titan’s “magic islands” aren’t islands, or bubbles
   Mysterious disappearing features in the lakes of Saturn’s moon Titan are caused by sunlight reflecting off giant waves, said planetary scientist Alexander Hayes of Cornell University.
   These features were named “magic islands” when they were first spotted in 2014. As recently as April 2017, planetary scientists thought they had the islands solved: They seemed to be the result of champagnelike bubbles of nitrogen burbling through the moon’s methane and ethane seas (SN Online: 4/18/17).

But Hayes presented newly analyzed data from August 2014, when Cassini looked at Kraken Mare, the moon’s largest northern sea, in radar and infrared wavelengths within two hours of each other. The radar images showed a magic island, and the infrared ones showed a peak in brightness at the same spot.

Because the observations were taken two hours apart, the island probably couldn’t have been due to bubbles, Hayes said — bubbles would pop or disperse too quickly. Instead, he thinks the brightening could be the glint of sunlight reflecting directly off of giant waves on the lake, like how the ocean ripples with gold at sunset. Simulations of Titan’s atmosphere suggest these waves could be raised by winds as slow as 0.5 meters per second, which would barely move a wind vane on Earth.

5. Enceladus’ plumes may brighten by the pull of another moon
   Saturn’s tiny moon Enceladus has plumes that may be driven by nudges from another moon.

The spurts of liquid water were discovered in 2006. Over the next six years, scientists noticed that the plumes varied in brightness (a proxy for how much material is gushing from the moon) on a daily cycle, probably driven by Saturn’s different positions in Enceladus’ sky.

Then, in 2015 some researchers noted that the plumes’ overall brightness had been decreasing since the beginning of the Cassini mission.

One possible explanation was that the plumes changed with Saturn’s seasons. Another was that ice built up in the vents, clogging them and decreasing the flow. But looking at the full 13-year dataset, planetary scientist Francis Nimmo found that the plumes grow brighter in a regular cycle every four and 11 years. The pattern is too coherent to be explained by clogged vents, said Nimmo, of the University of California, Santa Cruz. Oddly, the plume grew brighter in 2017, so the seasonal explanation doesn’t fit either.

The variations could be explained by a neighboring moon, Dione. Every time Dione and Enceladus line up, their gravitational stress on each other could force Enceladus’ vents open a bit more, causing the plumes to grow brighter.

Unsolved enigmas
So far, analyzing data from Cassini hasn’t answered all of scientists’ questions. Is Enceladus the only moon with plumes? Dione showed signs of activity, too, but Cassini wasn’t able to confirm it. How thick is Enceladus’ ice sheet? Why are Titan’s smaller lakes full of clear, pure methane, when scientists expected the lakes to be clogged with hydrocarbon silt?

Even though the spacecraft is gone, it left decades’ worth of data to sift through in search of answers. “Cassini is going to keep on giving as long as we keep looking,” Hayes said.

Editors’ note: This story was updated on March 21, 2018, to include the affiliations of Jeff Cuzzi and Francis Nimmo.

When the 2017 Great American Eclipse hit totality and the sky went dark, bees noticed.

Microphones in flower patches at 11 sites in the path of the eclipse picked up the buzzing sounds of bees flying among blooms before and after totality. But those sounds were noticeably absent during the full solar blackout, a new study finds.

Dimming light and some summer cooling during the onset of the eclipse didn’t appear to make a difference to the bees. But the deeper darkness of totality did, researchers report October 10 in the Annals of the Entomological Society of America. At the time of totality, the change in buzzing was abrupt, says study coauthor and ecologist Candace Galen of the University of Missouri in Columbia.
The recordings come from citizen scientists, mostly school classes, setting out small microphones at two spots in Oregon, one in Idaho and eight in Missouri. Often when bees went silent at the peak of the eclipse, Galen says, “you can hear the people in the background going ‘ooo,’ ‘ahh’ or clapping.”
There’s no entirely reliable way (yet) of telling what kinds of bees were doing the buzzing, based only on their sounds, Galen says. She estimates that the Missouri sites had a lot of bumblebees, while the western sites had more of the tinier, temperature-fussy Megachile bees.
More western samples, with the fussier bees, might have let researchers see an effect on the insects of temperatures dropping by at least 10 degrees Celsius during the eclipse. The temperature plunge in the Missouri summer just “made things feel a little more comfortable,” Galen says.

This study of buzz recordings gives the first formal data published on bees during a solar eclipse, as far as Galen knows. “Insects are remarkably neglected,” she says. “Everybody wants to know what their dog and cat are doing during the eclipse, but they don’t think about the flea.”

Vinita Surukan knew the mosquitoes were trouble. They attacked her in swarms, biting through her clothes as she worked to collect rubber tree sap near her village in Sabah, the northern state of Malaysia. The 30-year-old woman described the situation as nearly unbearable. But she needed the job.

There were few alternatives in her village surrounded by fragments of forest reserves and larger swaths of farms, oil palm plantations and rubber tree estates. So she endured until a week of high fever and vomiting forced her to stop.
The night of July 23, Surukan was trying to sleep off her fever when the clinic she visited earlier in the day called with results: Her blood was teeming with malaria parasites, about a million in each drop. Her family rushed her to the town hospital where she received intravenous antimalarial drugs before being transferred to a city hospital equipped to treat severe malaria. The drugs cleared most of the parasites, and the lucky woman was smiling by morning.

Malaria has terrorized humans for millennia, its fevers carved into our earliest writing on ancient Sumerian clay tablets from Mesopotamia. In 2016, four species of human malaria parasites, which are spread by mosquito from person to person, infected more than 210 million people worldwide, killing almost 450,000. The deadliest species, Plasmodium falciparum, causes most of the infections.

But Surukan’s malaria was different. Hers was not a human malaria parasite. She had P. knowlesi, which infects several monkey species. The same parasite had recently infected two other people in Surukan’s village — a man who hunts in the forest and a teenager. Surukan suspects that her parasites came from the monkeys that live in the forest bordering the rubber tree estate where she worked. Some villagers quit working there after hearing of Surukan’s illness.

Monkey malaria, discovered in the early 1900s, became a public health concern only in the last 15 years. Before that, scientists thought it was extremely rare for monkey malaria parasites, of which there are at least 30 species, to infect humans.
Yet since 2008, Malaysia has reported more than 15,000 cases of P. knowlesi infection and about 50 deaths. Infections in 2017 alone hit 3,600.
People infected with monkey malaria are found across Southeast Asia near forests with wild monkeys. In 2017, another species of monkey malaria parasite, P. cynomolgi, was found in five Malaysians and 13 Cambodians. And by 2018, at least 19 travelers to the region, mostly Europeans, had brought monkey malaria back to their home countries.

The rise of monkey malaria in Malaysia is closely tied to rapid deforestation, says Kimberly Fornace, an epidemiologist at the London School of Hygiene and Tropical Medicine. After testing blood samples of nearly 2,000 people from areas in Sabah with various levels of deforestation, she found that people staying or working near cut forests were more likely than people living away from forests to have P. knowlesi infections, she and colleagues reported in June in PLOS Neglected Tropical Diseases. Stepping over felled trees, humans move closer to the monkeys and the parasite-carrying mosquitoes that thrive in cleared forests.
It’s out there
There’s no feasible way to treat wild monkeys for an infection that they show no signs of. “That’s the problem with P. knowlesi,” says Singapore-based infectious disease specialist Fe Espino, a director of the Asia Pacific Malaria Elimination Network.

In 2015, the World Health Organization set a goal for 2030: to stop malaria transmission in at least 35 of the 91 malaria-endemic countries. WHO targets the four human malaria parasites: P. falciparum, P. vivax, P. malariae and P. ovale. Monkey malaria is excluded from the campaign because the agency regards it as an animal disease that has not been shown to transmit among humans.

But as countries reduce human malaria, they will eventually have to deal with monkey malaria, Espino says, echoing an opinion widely shared by monkey malaria scientists.

“Something nasty” could emerge from the pool of malaria parasites in monkeys, says malariologist Richard Culleton of Nagasaki University in Japan. Culleton studies the genetics of human and monkey malaria. Malaria parasites can mutate quickly — possibly into new types that can more easily infect humans (SN: 9/6/14, p. 9). To Culleton, the monkey malaria reservoir “is like a black box. Things come flying out of it occasionally and you don’t know what’s coming next.”
Malaysia is very close to reaching the WHO target of human malaria elimination. In 2017, only 85 people there were infected with human malaria. But that success feels hollow as monkey malaria gains a foothold. And while monkey malaria has swelled into a public health threat only in Malaysia, the same could happen in other parts of Southeast Asia and beyond. Even in southeastern Brazil, where human malaria was eliminated 50 years ago, the P. simium malaria parasite that resides in howler monkeys caused outbreaks in humans in 2015 and 2016.

From tool to threat
In the late 1800s, scientists discovered the Plasmodium parasite and its Anopheles mosquito carriers. Humans retaliated by draining marshes to stop mosquito breeding and spraying insecticides over whole communities. Governments and militaries pursued antimalarial drugs as the disease claimed countless soldiers during the two World Wars.

Scientists soon found malaria parasites in birds, rodents, apes and monkeys. To the researchers, the parasites found in monkeys were a tool for testing antimalarial drugs, not a threat. An accident, however, showed otherwise.
In 1960, biologist Don Eyles had been studying the monkey malaria P. cynomolgi at a National Institutes of Health lab in Memphis, Tenn., when he fell ill with malarial fevers. He had been infected with the parasites found in his research monkeys. His team quickly confirmed that the malaria parasites in his monkeys could be carried by mosquitoes to humans. Suddenly, monkey malaria was not just a tool; it was an animal disease that could naturally infect humans.
The news shook WHO, McWilson Warren said in a 2005 interview recorded by the Office of NIH History. Warren, a parasitologist, had been Eyles’ colleague. Five years before Eyles became infected, WHO had launched the Global Malaria Eradication Programme. Banking on insecticides and antimalarial drugs, the agency had aimed to end all malaria transmissions outside of Africa. A monkey malaria that easily infects humans would sink the program because there would be no way to treat all the monkeys.

A team of American scientists, including Eyles and Warren, traveled to Malaysia — then the Federation of Malaya — where the P. cynomolgi parasites that infected Eyles came from. Funded by NIH, the scientists worked with colleagues from the Institute of Medical Research in Kuala Lumpur, established in 1900 by the British to study tropical diseases.

From 1961 to 1965, the researchers discovered five new species of monkey malaria parasites and about two dozen mosquito species that carry the parasites. But the researchers did not find any human infections. Then, in 1965, an American surveyor became infected with P. knowlesi after spending several nights camping on a hill about 160 kilometers inland from Kuala Lumpur.

Warren surveyed the forested area where the infected American had camped. The hill sat beside a meandering river. Monkeys and gibbons, a type of ape, lived on the hill and in adjacent forests. The closest house was about two kilometers away. Warren sampled the blood of four monkeys and more than 1,100 villagers around the hill; he collected mosquitoes too.

He found P. knowlesi parasites in the monkeys, but none among the villagers. Only one mosquito species, A. maculatus, appeared capable of transmitting malaria between monkeys and humans, but Warren deemed its numbers too low to matter. He concluded that monkey malaria stayed in the forests and rarely ever spilled into humans.

With those results, NIH ended the monkey malaria project, Warren said, and the Institute of Medical Research in Kuala Lumpur returned to its primary focus: human malaria, dengue and other mosquito-borne diseases. Monkey malaria was struck off the list of public health concerns.

Wake-up call
P. knowlesi landed back in the spotlight in 2004, with a report in the Lancet by malariologist Balbir Singh and his team. The group had found 120 people infected over two years in southern Malaysian Borneo. The patients were mostly indigenous people who lived near forests. Clinicians initially had checked the patients’ blood samples under microscopes — the standard test — and diagnosed the parasites as human malaria. But when Singh, of Universiti Malaysia Sarawak, applied molecular tools that identify parasite species by their DNA, he revealed that all the samples were P. knowlesi. Monkey malaria was breaking out of the diminishing forests.

By 2018, P. knowlesi had infected humans in all Southeast Asian countries except for East Timor. Singapore, declared malaria free in 1982, reported that six soldiers were infected with P. knowlesi from wild monkeys in a forest reserve. The parasite also turned up in almost 380 out of 3,700 visitors to health clinics in North Sumatra, Indonesia, an area that is close to being deemed free of human malaria.
Many scientists now recognize P. knowlesi as the fifth malaria parasite species that can naturally infect humans. It is also the only one to multiply in the blood every 24 hours, and it can kill if treatment is delayed. People pick up P. knowlesi parasites from long-tailed macaques, pig-tailed macaques and Mitred leaf monkeys. These monkeys range across Southeast Asia. So far, malaria parasites have been found in monkeys near or in forests, but rarely in monkeys in towns or cities.

Scientists propose several reasons for the recent rise in monkey malaria infections, but two stand out: improvement in malaria detection and forest loss.

Malaysia, for instance, finds more monkey malaria cases than other Southeast Asian countries because it added molecular diagnostic tools in 2009. Other countries use only microscopy for detection, says Rose Nani Mudin, who heads the vectorborne disease sector at Malaysia’s Ministry of Health. Since 2008, annual monkey malaria cases in Malaysia have climbed tenfold, even as human malaria cases have plummeted. “Maybe there is a genuine increase in [monkey malaria] cases. But with strengthening of surveillance, of course you would detect more cases,” she says.

Data collected by Malaysia’s malaria surveillance system have also revealed strong links between infection risk and deforestation. Fornace, the epidemiologist, examined the underlying drivers of monkey malaria in Surukan’s home state of Sabah. Fornace mapped monkey malaria cases in 405 villages, based on patient records from 2008 to 2012. Satellite data showed changes in forested areas around those villages. The villages most likely to report monkey malaria infections were those that had cut more than 8 percent of their surrounding forests within the last five years, she and colleagues reported in 2016 in Emerging Infectious Diseases.
Fornace’s team went into the field for a follow-up study, published in June in PLOS Neglected Tropical Diseases. The team collected blood samples from almost 2,000 people in two areas in Sabah and checked for current and past malaria infection. People who farmed or worked in plantations near forests had at least a 63 percent higher risk of P. knowlesi infection, and — like in the 2016 study — forests and cleared areas escalated risk of infection.

“It feels almost like P. knowlesi follows deforestation,” Fornace says. Several years after a forest is cut back, nearby communities “get a peak of P. knowlesi.”

Today, the hill where the American surveyor camped in 1965 is a small island in a sea of oil palm estates. From 2000 to 2012, Malaysia cleared a total amount of forest equaling 14.4 percent of its land area, more than any other country, according to a study published in 2013 in Science. A study in 2013 in PLOS ONE used satellite images to show that in 2009, only one-fifth of Malaysian Borneo was intact forest. Almost one-fourth of all forest there had been logged, regrown and logged many times over.

Since 2008, oil palm acreage in Malaysian Borneo has increased from 2.08 million hectares to 3.1 million, according to the Malaysian Palm Oil Board. In Malaysia, the four states hit hardest by deforestation — Sabah, Sarawak, Kelantan and Pahang — report 95 percent of the country’s P. knowlesi cases.
Fornace thinks deforestation and the ecological changes that come with it are the main drivers of monkey malaria’s rise in Malaysia. She has seen long-tailed macaques spend more time in farms and near houses after their home forests were being logged. Macaques thrive near human communities where food is abundant and predators stay out. Parasite-carrying mosquitoes breed in puddles made by farming and logging vehicles.

Where monkeys go, mosquitoes follow. Indra Vythilingam, a parasitologist at University of Malaya in Kuala Lumpur, studied human malaria in indigenous communities in the early 1990s. Back then, she rarely found A. cracens, the mosquito species that carries monkey malaria in Peninsular Malaysia. But in 2007, that species made up over 60 percent of mosquitoes collected at forest edges and in orchards, she reported in 2012 in Malaria Journal. “It’s so much easier to find them” now, she says.

As Fornace points out, “P. knowlesi is a really good example of how a disease can emerge and change” as land use changes. She recommends that when big projects are evaluated for their impact on the economy and the environment, human health should be considered as well.

What to expect
While P. knowlesi cases are climbing in Malaysia, scientists have found no evidence that P. knowlesi transmits directly from human to mosquito to human (though many suspect it happens, albeit inefficiently).
Following a review by experts in 2017, WHO continues to exclude P. knowlesi from its malaria elimination efforts. Rabindra Abeyasinghe, a tropical medicine specialist who coordinates WHO malaria control in the western Pacific region, says the agency will reconsider P. knowlesi as human malaria if there is new evidence to show that the parasite transmits within human communities.

In Malaysia last year, only one person died from human malaria, but P. knowlesi killed 11. “We don’t want that to happen, which is why [P. knowlesi] is our priority even though it is not in the elimination program,” says Rose Nani Mudin from the country’s Ministry of Health.

Unable to do much with the monkeys in the trees, Malaysian health officers focus on the people most likely to be infected with P. knowlesi. Programs raise awareness of monkey malaria and aim to reduce mosquitoes around houses. New mosquito-control methods are needed, however, because conventional methods like insecticide-treated bed nets do not work for monkey malaria mosquitoes that bite outdoors around dusk.

Fighting malaria is like playing chess against an opponent that counters every good move we make, says Culleton in Japan. Malaria parasites can mutate quickly and “go away and hide in places and come out again.” Against malaria, he says, “we can never let our guard down.”

This article appears in the November 10, 2018 Science News with the headline, “The Next Malaria Menace: Deforestation brings monkeys and humans close enough to share an age-old disease.”

Editor’s note: This story was updated on November 6, 2018 to correct the WHO’s position on monkey malaria. The agency excludes monkey malaria parasites from its malaria eradication goals, not because those particular parasites rarely infect humans, but because the parasites have not been shown to transmit among humans.

The United States is poised to take a powerful economic hit from climate change over the next century. Heat waves, wildfires, extreme weather events and rising sea levels could cost the country hundreds of billions of dollars in lost labor, reduced crop yields, health problems and crumbling infrastructure.

A report authored by hundreds of U.S. climate scientists from 13 federal agencies presents a stark picture of the country’s fate due to climate change. The Fourth National Climate Assessment, released November 23, predicts the U.S. economy will shrink by as much as 10 percent by the end of the century if global warming continues apace.
A separate report released November 27 by the United Nations Environment Programme reveals that in 2017, global emissions of carbon dioxide — a major driver of warming — rose for the first time in three years. That suggests that the nations that promised to curb emissions as part of the historic 2015 Paris agreement are falling short (SN: 1/9/16, p. 6).

It’s unclear what effect, if any, the reports will have on the U.S. government’s strategy on dealing with climate change and its consequences. President Donald Trump has previously announced he would withdraw the United States from the Paris agreement (SN Online: 6/1/17). And on November 26, Trump told reporters that he had read “some of” his scientists’ report. “It’s fine,” he said. But when it comes to the dire predictions of economic losses, he added, “I don’t believe it.”

The National Climate Assessments are mandated by Congress and produced every four years, focusing on the risks of climate change specifically to the United States. What’s different about the new report compared with previous editions is its precision about the risks to different parts of the U.S. economy, putting a price tag on the potential losses in agriculture, trade and energy generation.

To put a dollar value on bad air quality or worsening heat waves, for instance, scientists try to assess the measurable impacts of those issues — for example, the number of days of work or school missed, or the number of doctors’ visits triggered (SN Online: 10/14/18).
The more-than-1,600-page report includes detailed examinations of the effects of climate change on the country’s different regions. People living in the northeastern United States, for example, will be among the hardest hit by deaths due to poor air quality and temperature extremes by the end of the century. Labor losses in the southeastern United States are the highest of all regions, as are projected damages to roads and bridges, the report found.

Meanwhile, the Midwest will see the highest increase in premature deaths from increased amounts of ozone. And the Southwest, which includes California in these analyses, will suffer from extreme heat, drought and an increase in future cases of the mosquito-borne West Nile virus.

The report estimates that cumulatively the country will spend $23 billion responding to wildfires by the end of the century, even if greenhouse gas emissions are modestly reduced. The Southwest will bear the brunt of that impact, spending $13 billion dollars.

The report also details the many ways in which climate change is already hurting the country economically. For example, three storms that made landfall during the 2017 Atlantic hurricane season — Harvey, Irma and Maria — together cost the United States at least $265 billion, according to the National Oceanic and Atmospheric Administration.

By continuing on its current trajectory of greenhouse gas emissions, the “business-as-usual” scenario, the United States will see the greatest losses, the assessments concludes. However, the report also considers climate impacts in an alternate future, in which the world has taken modest actions to curb greenhouse emissions, including using more carbon-neutral fuels and the growth of technological innovations to remove carbon dioxide from the atmosphere (SN Online: 10/20/18).

Earth’s heart may have a secret chamber. The planet’s inner core isn’t just a solid ball of nickel and iron, researchers say, but contains two layers of its own: a distinct central region nestled within an outer shell.

Scientists say they have confirmed the existence of this innermost inner core using a type of previously undescribed seismic wave that not only travels through Earth’s core but also bounces back and forth through the interior, collecting invaluable data about the core’s structure along the way.
Focusing on earthquakes of magnitude 6 or larger that struck in the last decade, the researchers combined data on these quakes that were collected at seismic stations around the world. Combining these signals made it possible to detect even very faint reflections of the seismic waves. Of the 200 or so quakes analyzed, 16 events spawned seismic waves that detectably bounced through the inner core multiple times.

The origin, structure and fate of Earth’s core is of intense interest because the core generates the planet’s magnetic field, which shields the Earth from charged particles ejected by the sun and helps keep the planet’s denizens safe from too much radiation.

“Understanding how the magnetic field evolves is extremely important for the life on Earth’s surface,” says Hrvoje Tkalčić, a seismologist at the Australian National University in Canberra.

The entire core, about 6,600 kilometers across, consists of two main parts: a liquid outer core and a solid inner core (SN: 1/23/23). As iron-rich fluid circulates in the outer core, some of the material cools and crystallizes, sinking to form a solid center. That interplay generates Earth’s magnetic field.

When this swirling dance first began isn’t certain, but some studies suggest it was as recent as 565 million years ago, just a fraction of Earth’s 4.6-billion-year-long life span (SN: 1/28/19). That dance has faltered from time to time, its stuttering steps preserved in tiny magnetic grains in rocks. These data suggest the planet’s magnetic poles have flip-flopped many times over the years, temporarily weakening the magnetic field (SN: 2/18/21). As more and more crystals cool, the dance will eventually slow and stop, shutting off the planet’s magnetic field millions or billions of years from now.

Different types and structures of minerals, as well as different amounts of liquid in the subsurface, can change the speed of seismic waves traveling through Earth, offering clues to the makeup of the interior. In 2002, researchers noted that seismic waves traveling through the innermost part of Earth move slightly slower in one direction relative to the planet’s poles than in other directions. That suggests there’s some oddity there — a difference in crystal structure, perhaps. That hidden heart, the team suggested, might be a kind of fossil: a long-preserved remnant of the core’s early formation.

Since that observation, Tkalčić and others have pored over seismic data, finding independent lines of evidence that help support the idea of an innermost inner core. The reverberating seismic waves, described February 21 in Nature Communications, also show a slowdown, and are the strongest evidence yet that this hidden heart exists.
Using that seismic data, Tkalčić and seismologist Thanh-Son Phạm, also of the Australian National University, estimate that this inner heart is roughly 600 kilometers across, or about half the diameter of the full inner core. And the pair was able to assess the direction of the slowest waves at about 50 degrees relative to the Earth’s rotation axis, providing more insight into the region.

The exact source of the wave slowdown isn’t clear, Tkalčić says. The phenomenon might be related to the structure of the iron crystals, which may be packed together differently farther into the center. Or it could be from a different crystal alignment caused by some long-ago global event that changed how inner core crystals solidified out of the outer core.

The inner core holds many other mysteries too. Lighter elements present in small amounts in the core — hydrogen, carbon, oxygen — may flow around the solid iron in a liquidlike “superionic” state, further complicating the seismic picture (SN: 2/9/22).

By identifying and reporting seismic waves that bounced back and forth through the planet’s interior multiple times, the researchers have made an invaluable contribution that will help researchers study the core in new ways, says seismologist Paul Richards of Columbia University’s Lamont-Doherty Earth Observatory in Palisades, N.Y.

Still, the team’s interpretation of the inner core’s structure from those waves “is probably more iffy,” says Richards, who wasn’t involved in the work.

One reason for this uncertainty is that as the waves bounce back and forth, they can become weaker and more difficult to see in the data, he says. “Many further observations will help decide” what these new data can reveal about the heart of the planet.