Seals and sea lions provide clues to evolution of vocalization

A harbor seal relaxing on shore. (Wikipedia Commons, Charles J. Sharp)

Neuroscientists uncovered new insights into a key evolutionary question: Why can humans talk when most animals can’t? 

The journal Science published the research led by Emory University and the New College of Florida. The findings suggest that seals and sea lions may have vocal flexibility as a side effect of developing a brain “bypass” for voluntary breath control. This same bypass allowed them to adapt to aquatic life. 

The comparative study examined the brains of coyotes along with those of sea lions, elephant seals and harbor seals — marine carnivores with varying degrees of vocal control that are evolutionary cousins to canines. 

Seals are among the few animal species known to have the super vocal flexibility that allows them to mimic human voices. Sea lions have also demonstrated good vocal plasticity on a more limited scale. The neurobiology of these capabilities, however, was not known. 

Senior author Gregory Berns, Emory professor of psychology, and first author Peter Cook, a former Emory postdoctoral fellow, used the technique of diffusion magnetic resonance imaging (MRI) on post-mortem animal brains, giving them a view of connective neural pathways across species. 

All the brains used in the study came from wild animals that died naturally in rehabilitation facilities or had to be euthanized due to injuries.

Read the full story here.

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Accuracy test for protein language models shines light into AI 'black box'

Yana Bromberg, right, professor of biology and computer science, and R. Prabakaran, a postdoctoral fellow in the Bromberg lab, are developing computational techniques to study biological complexity. (Photo by Carol Clark)

AI language models, used to generate human-like text to power chatbots and create content, are also revolutionizing biology by treating complex biological data like a language. Language models are increasingly used, for example, to find patterns in DNA and proteins to make predictions and speed research into biological complexity. 

A critical gap, however, is the lack of a method to estimate the reliability of these predictions. 

Computational biologists at Emory University have bridged this gap, developing a simple way to test the accuracy of a language model’s understanding of proteins. Nature Methods published their system, which scores the reliability of a model’s predictions by comparing how it “embeds,” or numerically codifies, synthetic random proteins versus proteins found in nature. 

“To the best of our knowledge, our framework is the first generalized method to quantify protein sequence embedding reliability,” says Yana Bromberg, senior author of the paper and Emory professor of biology and computer science. 

“Our method is a simple, elegant solution to a complex problem,” adds R. Prabakaran, first author of the study and a postdoctoral fellow in the Bromberg lab. “It’s a foundational method with a lot of scope for a range of language models in science.” 

Read the full story here.

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Turning Over a New Leaf in Analyses of Natural Products

Emory graduate student William Crandall loves working at the nexus of nature and cutting-edge technology. (Photo by Tharanga Samarakoon)

Scientists developed a new way to help understand what happens in the body when people consume a plant product and the many chemicals it contains. The American Chemical Society’s Journal of Natural Products published the method to quickly analyze the effects of a natural product, developed at Emory University. 

As a test case, the paper focused on biotransformation of chemicals from the kratom plant by human liver cells in a laboratory dish. The researchers developed an automated method — based on high-resolution mass spectrometry and molecular network mapping — to gain a detailed, big-picture view of the resulting metabolites, or chemicals produced. 

The new, streamlined methodology can be broadly applied to nutrition and dietary supplement research, filling a critical gap in the field. 

“Plants evolved extraordinarily complex chemical defenses and signaling systems,” says Cassandra Quave, co-senior author of the study and professor of dermatology at Emory School of Medicine and the Center for the Study of Human Health. “Our new approach in molecular mapping gives us a way to follow how that chemical complexity is reshaped by human metabolism.” 

“Our technique does not just look at how one compound in this plant is metabolized,” adds William Crandall, first author of the study and a PhD student of molecular and systems pharmacology in Emory’s Laney Graduate School. “It shows how dozens of compounds are metabolized at one time.”

“This method marks a major, transformative step in natural products research,” says Dean Jones, co-senior author of the paper and professor in Emory School of Medicine. “A process that used to require years of work now takes just days.”

Read the full story here.

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Epigenetics linked to high-altitude adaptation in Andes

Indigenous people living at high altitude in the Andean highlands have adapted to one of the most extreme environments ever inhabited by humans. (Getty Images/Oleh Slobodeniuk)

DNA sequencing technology makes it possible to explore the genome to learn how humans adapted to live in a wide range of environments. Research has shown, for instance, that Tibetans living at high altitude in the Himalayas have a unique variant of a gene that expands the oxygen-carrying capacity of their blood. 

Scientists, however, have not found a strong signal for this “high-altitude gene” in the genomes of Indigenous people living in the Andes Mountains of South America. It’s been less clear how people adapted to the altitudes greater than 2,500 meters in the Andean highlands, where low-oxygen levels, frigid temperatures and intense ultraviolet radiation make life challenging in the extreme. 

A study led by anthropologists at Emory University took a new approach to explore this Andean mystery.

Read the full story here.

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Electric charge connects jumping worm to prey

A tiny worm that leaps high into the air — up to 25 times its body length — to attach to flying insects uses static electricity to perform this astounding feat, scientists have found. The journal PNAS published the work on the nematode Steinernema carpocapsae, a parasitic roundworm, led by researchers at Emory University and the University of California, Berkeley. 

“We’ve identified the electrostatic mechanism this worm uses to hit its target, and we’ve shown the importance of this mechanism for the worm’s survival,” says co-author Justin Burton, an Emory professor of physics whose lab led the mathematical analyses of laboratory experiments. “Higher voltage, combined with a tiny breath of wind, greatly boosts the odds of a jumping worm connecting to a flying insect.” 

“You might expect to find big discoveries in big animals, but the tiny ones also hold a lot of interesting secrets,” adds Victor Ortega-Jiménez, co-lead author and assistant professor of biomechanics at the University of California, Berkeley. He conducted the experiments, including the use of highspeed microscopy techniques to film the parasitic worm — whose length is about the diameter of a needle point — as it leaped onto electrically charged fruit flies. 

The researchers showed how a charge of a few hundred volts, similar to that generated by an insect’s wings beating the air, initiates an opposite charge in the worm, creating an attractive force. They identified electrostatic induction as the charging mechanism driving this process.

Read the full story here.

New Method to Control Dengue Mosquito Shows Public Health Benefit

In advance of the rainy season, local public health officials sprayed a long-lasting insecticide, safe for indoor use, targeted to areas where the Aedes mosquito prefers to hang out.

A novel disease prevention strategy — targeting a mosquito that spreads the dengue virus — significantly reduces both the mosquito numbers and cases of disease across a community, finds a major new study. New England Journal of Medicine published the results of the large, randomized clinical trial — considered the gold standard for evaluating the effectiveness of an intervention — led by Emory University. 

The research was conducted in Merida, a city of one million in the Mexican state of the Yucatan, through a close collaboration with the Autonomous University of the Yucatan, the Yucatan Ministry of Health and the Federal Ministry of Health of Mexico. 

The project tested an intervention that previous Emory research found promising: Targeted indoor residual spraying of insecticide, or TIRS, conducted before an outbreak occurs. The method is aimed at a particular species of mosquito, Aedes aegypti, that is perfectly adapted to live with humans in an urban setting. 

“Our study showed that the TIRS method reduced numbers of these mosquitos by 6o percent for a period of six months,” says Gonzalo Vazquez-Prokopec, senior author of the study and Emory professor of environmental sciences. “The results also quantified a 24 percent mean reduction community-wide in cases of dengue fever, even in the context of a record-breaking outbreak of dengue in Merida.”

Read the full story here.

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Exploring the frontiers of data science

Satellite technology is transforming the field of geography, says Xiao Huang. "It's kind of like being an astronaut in that satellites give you a view of Earth from space."

As a high-tech geographer, Xiao Huang uses remove sensing and AI for insights into how to design more equitable cities, improve management of natural resources, lessen the impact of natural and human-caused disasters, and improve public health policies.

"I love geography and computer technology," says Huang, assistant professor in Emory's Department of Environmental Sciences. "I want to use my knowledge of these fields to help humanity, especially socially disadvantaged communities."

Read the full story here.

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Developing a new approach to control a dangerous urban mosquito in Ethiopia

Developing a new approach to control a dangerous, invasive mosquito in Ethiopia

Edilawit Mesfine, left, and Edel Seifu, both from Jigjiga University, collect data and larvae from a construction site. (Photo by Kim Awbrey)

Emory University received $2.8 million in funding from the Gates Foundation to support its work to develop and test a high-tech, low-cost method to control an invasive mosquito that poses a growing threat of urban malaria in Africa. The three-year project is focused on three cities in Ethiopia: Jigjiga, Semera and Logiya. 

The project’s novel approach to combating malaria combines on-the-ground knowledge of human and mosquito behaviors with detailed environmental imagery from drones and NASA satellites. Machine learning techniques will be applied to the data to develop a model — powered by artificial intelligence — for targeted public health interventions. 

The aim is to efficiently control populations of the invasive Anopheles stephensi mosquito by first, identifying water sources that are most likely to harbor the larvae during the dry season. And secondly, by sharing maps of these precise targets with local public health authorities — via a mobile phone app — to guide their larvae-eradication efforts in the most efficient and effective manner. 

The strategy is based on research on the ecology of stephensi in Jigjiga led by Gonzalo Vazquez-Prokopec, Emory professor of environmental sciences and co-principal investigator for the grant. “It sounds counterintuitive to focus mosquito-control efforts on the dry season,” Vazquez-Prokopec says. “Our research, however, shows that the dry season offers a perfect window of opportunity to cost-effectively control these mosquitoes.” 

Vazquez-Prokopec is an expert on the disease ecology of pathogens spread by vectors, such as mosquitoes. His research considers environmental factors as well as the interactions of mosquitoes, the pathogens they carry, and people. 

Read the full story here.

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A new clue to how multicellular life may have evolved

The idea for the work came from watching the filter feeding of stentors — trumpet-shaped, single-celled giants that float near the surface of ponds. (Getty Images)

Life emerged on Earth some 3.8 billion years ago. The “primordial soup theory” proposes that chemicals floating in pools of water, in the presence of sunlight and electrical discharge, spontaneously formed organic molecules. These building blocks of life underwent chemical reactions, likely driven by RNA, eventually leading to the formation of single cells. 

But what sparked single cells to assemble into more complex, multicellular life forms? 

Nature Physics published a new insight about a possible driver of this key step in evolution — the fluid dynamics of cooperative feeding. 

“So much work on the origins of multicellular life focuses on chemistry,” says Shashank Shekhar, lead author of the study and assistant professor of physics at Emory University. “We wanted to investigate the role of physical forces in the process.” 

Shekhar got the idea while watching the filter feeding of stentors — trumpet-shaped, single-celled giants that float near the surface of ponds. Through microscope video, he captured the fluid dynamics of a stentor in a liquid-filled lab dish as the organism sucked in particles suspended in the liquid. He also recorded the fluid dynamics of pairs and groups of stentors clumped together and feeding. 

The videos revealed a world similar to how Van Gogh saw the night sky, swirling with stars. 

“The project started with beautiful images of the fluid flows,” Shekhar says. “Only later did we realize the evolutionary significance of this behavior.”

Read the full story by clicking here.

'Doctors by Nature': In a new book, a biologist explores how animals heal themselves

Emory biologist Jaap de Roode with his two dogs, Tukkie and Cooper.

In 2010, Emory University biologist Jaap de Roode published the discovery that monarch butterflies use medicine to cure their offspring of disease. His lab revealed how, if infected with a parasite, the female butterflies prefer to lay their eggs on a species of milkweed containing higher levels of a toxic chemical. The caterpillars eat the milkweed, ingest the toxin, and reduce the parasite load in their bodies. 

With that finding, de Roode joined the vanguard of scientists uncovering how animals treat themselves for diseases. 

“We showed how even an insect with a teeny-tiny brain can medicate,” de Roode says. “From there it was a natural progression to the understanding that, in principle, any animal can do it.” 

In his new book, “Doctors by Nature: How Ants, Apes and Other Animals Heal Themselves,” de Roode explores the growing field of animal self-medication. He interviews scientists around the globe and describes research into how animals from ants to apes, birds to bears — even family dogs and cats — use various forms of medicine.

Read more about de Roode's book.

Atlanta Science Festival set to entertain, inspire and engage all ages

The festival culminates Saturday, March 22, in "Exploration Expo," a day-long celebration in Piedmont Park. Demonstrations by Emory chemist Douglas Mulford are among the perennial favorites.

By Carol Clark

Atlanta Science Festival returns March 8-22, with more than 100 events throughout the metro area, inviting the public to join fun, interactive and educational experiences. The acclaimed city-wide celebration, one of the largest of its kind in the country, showcases the myriad science, technology engineering and mathematics (STEM) innovations happening in Atlanta, including at Emory. 

“Not only does the Atlanta Science Festival spotlight the wonder of science in its various forms, we strive to do so by curating a two-week experience that’s as exciting and intriguing as possible,” says Meisa Salaita, executive co-director of Science ATL, the non-profit organization that engineers the festival. “We want to open minds, educate, inspire, entertain, and spark the interest of the scientists of tomorrow.” 

Now in its 12th year, the Atlanta Science Festival was co-founded by Emory, Georgia Tech and the Metro Atlanta Chamber. 

Members of the Emory community will help participants experience the wonders of science through spectacles like the chemistry of fireballs, a musical entertainment combined with a biology talk on the surprising abilities of animals to use medicine, a walking tour of campus science landmarks, a behind-the-scenes look at the latest advances in healthcare technology and much more. 

Creative events to engage participants with technology include “Data Poetics,” which will combine slam poetry and computer science on Thursday, March 13 at 7 p.m. at the Supermarket event space in Atlanta. The introductory workshop in how to use software to visualize data and add power to poetic expression will be co-hosted by Emily Wall, Emory assistant professor of computer science, Keke Wu, Emory postdoctoral researcher, and W. J. Lofton, an Atlanta poet. 

The idea for the event grew out of an Emory class that Wall and Lofton co-taught as part of the Emory Arts and Social Justice Fellows program, which pairs faculty with local artists to explore how creative thinking and artistic expression can inspire change. Their class was so successful that the duo wanted to introduce the concept to the wider public. 

Participants will write a data-driven poem about a social issue affecting Atlanta and then amplify their message through information visualizations. “Many people think of computer science as intimidating and too ‘mathy’ to be interesting,” Wall says. 

That attitude often changes when people learn simple ways to directly apply computer science to better communicate a human problem, she adds. “We want to give artists another tool, a way to make their art even more compelling.”

Click here for highlights of more festival events featuring members of the Emory community.

Plant extract inspires new chemistry and new early lead against triple-negative breast cancer

The extract that inspired the research comes from Curcuma phaeocaulis, a flowering plant in the ginger family. (Wagner Campelo / Alamy Stock Photo)

Chemists at Emory University invented a reaction to streamline the total synthesis of a compound, phaeocaulisin A, extracted from a plant used for centuries in traditional Chinese medicine. 

In laboratory dish experiments conducted with biologists at Winship Cancer Institute of Emory University, the researchers showed the compound’s efficacy against HER2-positive breast cancer cells and triple-negative breast cancer cells. An analogue of the compound the chemists constructed boosted this efficacy. 

“We not only efficiently replicated a complex natural product,” says Mingji Dai, Emory professor of chemistry. “We also improved upon it by turning it into a more potent compound.” 

The Journal of the American Chemical Society published the work, led by Dai and Yong Wan, professor of pharmacology and chemical biology at Emory School of Medicine and director of basic research for the Glenn Family Breast Center at Winship Cancer Institute.

Read the full story here.

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High temperatures dampen immune systems of wild capuchins

A capuchin mother carries a baby on her back. The study found that the immune systems of juveniles were most impacted by high temperatures. (Capuchins de Taboga)

High temperatures lower the immune performance of wild capuchin monkeys in Costa Rica, especially in young individuals, finds a new study published by Science Advances. The work, led by scientists at Emory University and the University of Michigan, provides some of the first data on the relationship between the immune system and ambient temperature in a wild mammal. 

“Capuchin monkeys are super intelligent, highly adaptive primates that do well in diverse ecosystems,” says Marcela Benítez, Emory assistant professor of anthropology and co-senior author of the paper. “The fact that we’re seeing their immune responses affected by high temperatures suggests that many mammalian species that are less adaptive may be experiencing even worse effects as average temperatures warm globally.” 

Read the full story.

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A snapshot of scientific thought on emotions in animals

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A snapshot of scientific thought on emotions in animals

Wild capuchin monkeys in Costa Rica where Emory anthropologist Marcela Benítez is studying their social behaviors. (Capuchinos de Taboga)

The journal Royal Society Open Science published a survey of 100 researchers of animal behavior, providing a unique view of current scientific thought on animal emotions and consciousness. 

“As far as we know, this is the first assessment of how animal behavior researchers across a range of disciplines think about emotions and consciousness in non-human animals,” says Marcela Benítez, assistant professor of anthropology at Emory University and corresponding author of the paper. “It gives us a snapshot in time so that 20 years from now, we can revisit how scientific experts may have changed their views.” 

A majority of the survey respondents ascribed emotions to “most” or “all or nearly all” non-human primates (98%), other mammals (89%), birds (78%), octopus, squids and cuttlefish (72%) and fish (53%). And most of the respondents ascribed emotions to at least some members of each taxonomic group of animals considered, including insects (67%) and other invertebrates (71%). 

The survey also included questions about the risks in animal behavioral research of anthropomorphism (inaccurately projecting human experience onto animals) and anthropodenial (willful blindness to any human characteristics of animals). 

“It’s surprising that 89% of the respondents thought that anthropodenial was problematic in animal behavioral research, compared to only 49% who thought anthropomorphism poses a risk,” Benítez says. “That seems like a big shift.” 

Anthropomorphism, she notes, has long been a leading argument against those who attributed feelings to animals.

Read the full story by clicking here.

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Spiny Mice Point to New Path in Neuroscience

Spiny mice live in arid environments in Africa, the Middle East and southern Asia.

By Carol Clark

Scientists zeroed in on brain circuitry powering the desire of spiny mice to live in large groups, opening the door to a new model for the study of complex social behaviors in mammals. 

Current Biology published the work led by researchers at Emory University. It shows that neural signaling from the brain’s anterior cingulate cortex to the lateral septum drives the preference for spiny mice (Acomys) to affiliate with large peer groups. 

“To our knowledge, this is the first study to identify neural circuitry that promotes group-size preferences in a mammal,” says Aubrey Kelly, senior author of the study and associate professor of psychology at Emory. “We hope that our work paves the way for new insights into complex social behaviors in a range of mammals, including humans.” 

The Kelly lab made the breakthrough by developing methods to use spiny mice as a laboratory model for social neuroscience. 

Read the full story.

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Large theropods thrived near South Pole, Australian tracks show

Melissa Lowery and Anthony Martin, co-authors of the new paper, examine a theropod track.

A discovery of dinosaur tracks on Australia’s southern coast — dating back to the Early Cretaceous when Australia was still connected to Antarctica — indicates that large theropod dinosaurs thrived in this polar environment, prowling the river floodplains when the ice thawed during the summers. 

The journal Alcheringa published the analyses of the tracks made in the Wonthaggi Formation south of Melbourne between 120 and 128 million years ago. The find includes 18 theropod tracks and four tracks made by ornithopods — small, herbivorous dinosaurs that may have been prey for the theropods. 

“These numerous tracks are the best evidence yet that these former polar environments supported large carnivores,” says Anthony Martin, first author of the study and a professor in Emory’s Department of Environmental Sciences. “The large theropods would likely have fed on prey such as smaller dinosaurs, fish and turtles.” 

Theropods, from the ancient Greek for “wild beast foot,” are a dinosaur clade characterized by walking on two legs and feet with three clawed toes. They belong to the same evolutionary group as Allosaurus, Tyrannosaurus rex and Velociraptor. 

The largest track from the current find was 18.5 inches long. “The hip height of that theropod would have been about the same as the full height of a tall, modern-day human — or a bit more than six feet tall,” Martin says.

Read the full story here.

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The promise and pitfalls of 'climatopias' for building resilience in coastal communities

"We need to invest in projects for low-income groups because they are the most impacted by climate change," says Jola Ajibade, associate professor in Emory's Department of Environmental Sciences. (Photo by Carol Clark)

By Carol Clark

Idowu (Jola) Ajibade grew up in Lagos, Nigeria, a low-lying city built around a lagoon bordered by the Atlantic Ocean. Flooding is a routine occurrence during the rainy season. 

“It was bad,” Ajibade recalls of living on the ground floor of a building during her early childhood. “We would get inundated with water until my family relocated to the upper level in a rental apartment. I don’t have many childhood photos or videos like most people. Our belongings got flooded out yearly — we replaced some items, but some things are just irreplaceable.” 

These experiences are part of what drove Ajibade, associate professor in Emory’s Department of Environmental Sciences, to become an environmental and human geographer. She explores how climate change is transforming the lives, livelihoods, social-cultural landscapes and housing access for low-income groups and historically marginalized communities. 

Nature recently published a commentary by Ajibade and Sameer Shah from the University of Washington considering whether futuristic settlements on water, so-called “climatopias,” are viable ways to build resilience in coastal communities. 

As urban populations boom, even as climate change exacerbates flood risks in coastal areas, governments are working with developers, architects and engineers to try to make their cities more resilient. Many leaders are promoting showcase climatopias as viable solutions. 

Ajibade and Shah, however, take a more cautious approach in their Nature commentary. “Ultimately, climatopias can become technical solutions to a complex global challenge only if stricter planning processes, impact assessments, ecosystem protection and justice for communities are at the heart of any coastal future,” the authors write. 

Examples of climatopias

The Maldives Floating City is a development of modular floating platforms taking shape in the Indian Ocean, set for completion in 2027. The development aims to help the Maldives, one of the world’s low-lying nations, survive the effects of rising sea levels. 

Maasbommel in the Netherlands offers an example of an amphibious climatopia. The 32 amphibious homes of Maasbommel are anchored to the ground but also fastened to flexible mooring posts that allow them to move upward by more than five meters and float during floods. 

Reclamation, or the practice of creating new land from oceans by filling the water with rock, cement and other materials, forms the basis for other climatopia projects worldwide. One famous example is Eko Atlantic, an enclave of sleek, modern skyscrapers rising on a two-square-mile platform of reclaimed land on the Lagos waterfront. 

Dredging for Eko Atlantic began in 2009, and construction is still underway. When completed, Eko Atlantic will comprise offices and luxury condos expected to house 250,000 residents, who will be protected from storm surges by an eight-mile-long, 20-foot-tall wall of concrete and granite. 

Developers laud Eko Atlantic as a way to attract transnational investment, drive economic growth, combat the effects of climate change and house more people in one of the world’s fastest-growing megacities. 

Getting multiple perspectives 

While working on her PhD as a graduate student at Western University in Canada in 2012, Ajibade returned to her hometown to research community vulnerability and resilience in Lagos, a city sharply divided between the rich and poor. 

“I talked to people who lived in slums and those in wealthy areas to get both their perspectives,” she says. “There was torrential rainfall during my visit and, at one point, I had to wade through chest-high water.” 

She notes that construction on the Eko Atlantic project has been blamed for displacing some communities and for diverting water in ways that increase the flooding burden on the poorest of the poor. Others counter that poor communities have caused the increase in flooding by building shanties on drainage systems and filling them with trash. 

Some believe that Eko Atlantic will benefit low-income people by providing service jobs. Others doubt that the economic boon of the pricy new real estate will “trickle down” in ways that benefit those who need it most. 

So is Eko Atlantic worth the billions of dollars that have already been invested in it during the past 16 years? 

“It depends on who you ask,” Ajibade says. 

Improving the drainage infrastructure throughout Lagos, including in the poorest areas, might be another solution that could benefit more people. 

“We need to invest in projects for low-income groups because they are the most impacted by climate change,” she notes. “Climatopias can’t be the focal solution, and they should be carefully considered so that they don’t damage fragile ecosystems, accelerate ocean colonialism or create even more problems for people who are already living on the margins of society.”

Related:

White House taps Emory expert to speak on climate resilience panel

Taking math by storm: Modeling how climate change may affect our coasts

White House taps Emory expert to speak on climate resilience panel

“The climate is changing. We also need to think about ways to change ourselves as a society so we can begin to meet the important challenges ahead of us,” says Idowu (Jola) Ajibade, associate professor in Emory University’s Department of Environmental Sciences. 

As a deadly heat waves blanketed parts of the United States, Ajibade spoke on a guest panel of experts for a meeting of the U.S. President’s Council of Advisors on Science and Technology (PCAST). PCAST consists of experts from who advise the president on policy matters where the understanding of science, technology and innovation is key. 

The public meeting, entitled “Social Impact of Research: Climate Resilience,” was livestreamed on July 11 and also recorded. 

Ajibade is an environmental and human geographer. She explores how climate change is transforming the lives, livelihoods, social-cultural landscapes and housing access for members of historically marginalized communities. 

“If we’re going to build resilience to climate change, we need multiple perspectives, multiple expertise and, certainly multiple methods,” Ajibade explains during her PCAST presentation. 

Watch the full presentation in the video above.

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Rabies outbreaks in Costa Rica cattle linked to deforestation

Cows in a forest of the Alajuela province of Costa Rica meander near the entrance to a cave where researchers are gathering data on vampire bats and the ecology of the rabies virus. Photo by Amanda Vicente.

By Carol Clark

Deforestation in Costa Rica raises the risk of cattle becoming infected with rabies by vampire bats, finds a new study. Emerging Infectious Diseases published the research by disease ecologists at Emory University. 

“A healthy tropical forest has phenomenal diversity — not just among plants and mammals like monkeys and bats, but also among microorganisms,” says Thomas Gillespie, Emory professor and chair of the Department of Environmental Sciences and senior author of the study. “When you destroy parts of a forest, the diversity goes down and the dynamics of disease transmission may change in a way that leads to the emergence of new pathogens or the reemergence of existing ones.” 

The Costa Rica economy relies heavily on ecotourism. Approximately 25% of its territory is protected under its National System of Conservation Areas, the largest percentage of protected areas accounted for by any country in the world, according to the Global Alliance of National Parks. 

Agriculture, however, is also an important economic sector and often encroaches into unprotected tropical forest areas. Livestock farms cover about 38% of the country’s territory, according to the United Nations Environment Program. 

“The government has done an amazing job of protecting much of its tropical forest,” Gillespie says. “In some areas, however, the country has high rates of deforestation due to clearing of the land for agricultural uses. It’s a big dichotomy.” 

Rabies is a viral disease most often transmitted by the bite of a rabid mammal. Vaccination campaigns have been largely effective at preventing rabies outbreaks in dogs in Costa Rica. The virus, though, keeps reemerging in cattle, spread by vampire bats. 

A vampire bat is held in a researcher's gloved hands. The bat's razor-sharp teeth allow it to make an incision in an animal without the animal feeling it. Photo by Neto Villalobos.

Found in tropical and subtropical areas of Central and South America, vampire bats feed solely on blood. Unlike other bats, they can walk — and even run — on land. They feed at night, stealthily approaching a sleeping mammal. Razor-sharp teeth and surgical precision allow the bats to make an incision in an animal, such as in the hock of a cow, without the animal feeling it. An anticoagulant in vampire bat saliva keeps the blood flowing as the bat laps up a meal. 

The researchers wanted to better understand the factors associated with rabies outbreaks in cattle in Costa Rica. They drew from data of the National Animal Health Service of Costa Rica to map the time and locations of rabies outbreaks in cattle from 1985 to 2020 in both northern and southern regions of the country where tropical forest has been cleared for agriculture. 

They also mapped land-use data across the same time for the outbreak sites, including a radius of 10 kilometers for each site, the maximum foraging range for vampire bats. They then used geographic information system software to generate spatial probability estimations based on these known outbreaks. 

The results showed a link between the location of forest habitat and an outbreak. Each one-kilometer increase in distance from forest increased the probability of an outbreak by 4%. The researchers theorize that decreased availability of bat-roosting sites within forested habitat appears to increase the preference of vampire bats to feed on cattle, as opposed to wild mammals. 

“We found the highest probability of rabies outbreaks in Puntarenas Province in the south, indicating the need for localized, preventative interventions in that region to avoid rabies reemergence in people,” says Julie Clennon, an eco-epidemiologist in Emory’s Department of Environmental Sciences and co-author of the study. 

A forest in Alajuela province with cleared patches of land due to agricultural activity. Photo by Amanda Vicente.

A growing number of studies show a similar pattern linking the destruction of tropical forests with disease reemergence, Gillespie says, including a reemergence of hanta viruses in the Amazon associated with soybean production and the reemergence of the Lassa virus in West Africa, linked to oil-palm production. 

In a previous study, the researchers and colleagues showed that shifts in the feeding preferences of vampire bats due to human land-use changes in Costa Rica altered the gut microbial communities and immune systems of the bats. Such shifts could potentially make bats more susceptible to pathogens and more likely to spread them. 

“When governments make decisions about large-scale land-use changes, they need to consider the potential of disease emergence, or reemergence, along with the potential for increased greenhouse-gas emissions,” Gillespie says. 

In addition to their association with the destruction of natural habitat, cows and other ruminant animals emit methane, a potent greenhouse gas, as they digest grasses. And the greenhouse gas nitrous oxide is emitted from the manure of ruminants. 

“As an individual, you may want to reduce beef in your diet as much as possible,” Gillespie says, “both to improve your own health and that of the planet. We are currently using natural resources at a rate that’s not sustainable.” 

First author of the current paper is Christie Jones, who did the work as a student in Emory’s 4+1 BS/MPH program, where she received a bachelors in environmental sciences before entering an accelerated program for a master of public health at Rollins School of Public Health. Jones is currently studying medicine at the American University of the Caribbean. Amanda Vicente, a former Emory postdoctoral fellow in the Gillespie lab who is now at the University of Oklahoma, is a co-author. 

The work was funded by Emory University’s Halle Institute for Global Research, the Department of Environmental Sciences and the Fox Center for Humanistic Inquiry, and the Fulbright Association.

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Identifying risks of human flea infestations in plague-endemic areas of Madagascar

A home in the Central Highlands of Madagascar. Residential structures vary greatly in rural areas. (Photos by Adelaide Miarinjara)

By Carol Clark

Madagascar is one of the last places where outbreaks of human bubonic plague still happen regularly. 

Fleas carrying the plague bacterium Yersinia pestis can spread the disease through their bites. And while a species commonly known as “the rat flea” has been fingered as the main culprit in plague outbreaks, a species known as “the human flea” may play a secondary role. 

As an investigator during plague outbreaks in rural Madagascar, medical entomologist Adelaide Miarinjara knew that many households were teeming with these human fleas. Miarinjara grew up in the island nation off the east coast of Africa and is now a postdoctoral fellow at Emory University, collaborating with the Pasteur Institute in Madagascar. 

“We have observed huge variability in the number of fleas in different households in the same village,” she says. “We might collect three or five fleas in one house and hundreds of them in another house.” 

Miarinjara led a study to solve the mystery of this variability. 

PLoS Neglected Diseases published her team’s findings: The abundance of human fleas is primarily associated with households that have a traditional dirt floor covered by a plant-fiber mat, as opposed to households with cement or board floors. A secondary risk factor was keeping animals in the house at night. 

“Flea larvae need humidity, but not too much humidity, to survive,” Miarinjara says, “so the dirt covered by the plant-fiber mat may be holding just the right amount of moisture for them to thrive.” 

She hopes that agencies seeking to improve people’s lives in plague-endemic areas of Madagascar focus on upgrading the flooring in homes and constructing sheds separate from the households for animals.

“Flea infestation raises the risk for getting diseases and it has a big impact on the quality of life,” Miarinjara says. “The constant bites are annoying and lead to lack of sleep.” 

Household flea infestations also promote the overuse of insecticides. Surveys by the researchers reveal that 80% of the households use insecticide to try to battle the fleas. Many people are buying liquid insecticides that are repackaged in empty plastic or glass containers, without labels or instructions for how to apply them, and sold in small, open-air markets. 

Improper use of insecticides is a health risk to people who may be overexposed to the chemicals.

“Overuse of these chemicals is also dangerous because some fleas are developing resistance to insecticides — the frontline tools for battling plague outbreaks,” Miarinjara says. 

“Poverty related to housing construction is a primary challenge that this research identified,” adds Thomas Gillespie, senior author of the study and professor and chair of Emory’s Department of Environmental Sciences. “Resurfacing dirt floors in homes with concrete could improve a range of health and quality-of-life issues, from reducing flea populations in homes to making the floors easier to clean of contaminants such as fecal matter tracked in from the outside.” 

The Gillespie lab is a pioneer in the “one health” approach to epidemics — studying the interactions of people, domestic animals, wildlife and ecosystems to understand how germs jump across species. 

Village residents gather to hear the research team brief them on the purpose of their visit. The women in the foreground are sitting on a traditional plant-fiber mat.

The plague has afflicted humans at least as far back as the Bronze Age and has persisted through the centuries. The advent of antibiotics — which can effectively treat plague — turned the disease into a horror story from the past for much of the world. 

In Madagascar, however, plague returns regularly to claim new victims. Cases typically originate in the rural rice-growing region of the central Highlands during the rainy season. Outbreaks there are associated with agriculture, deforestation, the black rat — and fleas. 

Different flea species have evolved to prefer the blood of one animal over another, although they may feed on a variety of organisms if they are hungry enough. 

Most plague research is centered on the rat flea, or Xenopsylla cheopis. Just one of its bites can transmit enough bacteria to infect someone with plague. In contrast, several bites from the human flea, Pulex irritans, are required to transmit the bacteria, making it a less potent spreader of plague but still a threat. 

For the current paper, the researchers collected fleas from 126 households in four different villages. Rural Madagascar homes typically consist of more than one level. The bottom level is often used to keep livestock overnight and the second and third floors are where members of the family sleep, cook and eat. 

Researchers collect the fleas captured overnight in a candle trap while members of a household watch.

The fleas were collected overnight on the second floor of the homes using simple traps — a lit candle set in a dish of soapy water. The fleas are attracted to the flickering light and drown when they hop into the dish. 

The researchers painstakingly removed each drowned flea using tweezers, set them to dry on absorbent paper, and then transferred them to test tubes for laboratory identification and analyses. 

The results showed that around 95% of the species collected in households were human fleas, mixed at times with a few rat fleas and a few from a third species that prefers to feed on cats and dogs. Collections were conducted in both the dry and rainy seasons with similar results. 

“We’re now looking deeper into what’s going on with insecticide use in households,” Miarinjara says. “We want to both sort out what is driving insecticide resistance among fleas and find ways to help people use insecticides safely and more effectively.” 

Co-authors of the current study include: Annick Reveloson, a PhD student at the University of Antananarivo in Madagascar; Stephen Mugel, an Emory PhD student set to graduate this May; Nick An, who graduated last year from Emory’s BS/MPH program; Andry Andriamiadanarivo, a technician at Centre ValBio in Madagascar; and Minoarisoa Rajerison, Rindra Randremanana and Romain Girod, research scientists at the Pasteur Institute in Madagascar. 

The research was funded by the Branco Weiss Society in Science Fellowship and the American Society of Tropical Medicine and Hygiene.

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