The Nose Knows: Dogs Are Being Trained to Detect the Coronavirus
Asher is eccentric and inquisitive. He loves an audience, likes keeping busy, and howls to be let through doors. He is a six-year-old working Cocker Spaniel, who, with five other furry colleagues, has now been trained to sniff body odor samples from humans to detect COVID-19 infections.
As the Delta variant and other new versions of the SARS-CoV-2 virus emerge, public health agencies are once again recommending masking while employers contemplate mandatory vaccination. While PCR tests remain the "gold standard" of COVID-19 tests, they can take hours to flag infections. To accelerate the process, scientists are turning to a new testing tool: sniffer dogs.
At the London School of Hygiene and Tropical Medicine (LSHTM), researchers deployed Asher and five other trained dogs to test sock samples from 200 asymptomatic, infected individuals and 200 healthy individuals. In May, they published the findings of the yearlong study in a preprint, concluding that dogs could identify COVID-19 infections with a high degree of accuracy – they could correctly identify a COVID-positive sample up to 94% of the time and a negative sample up to 92% of the time. The paper has yet to be peer-reviewed.
"Dogs can screen lots of people very quickly – 300 people per dog per hour. This means they could be used in places like airports or public venues like stadiums and maybe even workplaces," says James Logan, who heads the Department of Disease Control at LSHTM, adding that canines can also detect variants of SARS-CoV-2. "We included samples from two variants and the dogs could still detect them."
Detection dogs have been one of the most reliable biosensors for identifying the odor of human disease. According to Gemma Butlin, a spokesperson of Medical Detection Dogs, the UK-based charity that trained canines for the LSHTM study, the olfactory capabilities of dogs have been deployed to detect malaria, Parkinson's disease, different types of cancers, as well as pseudomonas, a type of bacteria known to cause infections in blood, lungs, eyes, and other parts of the human body.
COVID-19 has a distinctive smell — a result of chemicals known as volatile organic compounds released by infected body cells, which give off an odor "fingerprint."
"It's estimated that the percentage of a dog's brain devoted to analyzing odors is 40 times larger than that of a human," says Butlin. "Humans have around 5 million scent receptors dedicated to smell. Dogs have 350 million and can detect odors at parts per trillion. To put this into context, a dog can detect a teaspoon of sugar in a million gallons of water: two Olympic-sized pools full."
According to LSHTM scientists, COVID-19 has a distinctive smell — a result of chemicals known as volatile organic compounds released by infected body cells, which give off an odor "fingerprint." Other studies, too, have revealed that the SARS-CoV-2 virus has a distinct olfactory signature, detectable in the urine, saliva, and sweat of infected individuals. Humans can't smell the disease in these fluids, but dogs can.
"Our research shows that the smell associated with COVID-19 is at least partly due to small and volatile chemicals that are produced by the virus growing in the body or the immune response to the virus or both," said Steve Lindsay, a public health entomologist at Durham University, whose team collaborated with LSHTM for the study. He added, "There is also a further possibility that dogs can actually smell the virus, which is incredible given how small viruses are."
In April this year, researchers from the University of Pennsylvania and collaborators published a similar study in the scientific journal PLOS One, revealing that detection dogs could successfully discriminate between urine samples of infected and uninfected individuals. The accuracy rate of canines in this study was 96%. Similarly, last December, French scientists found that dogs were 76-100% effective at identifying individuals with COVID-19 when presented with sweat samples.
Grandjean Dominique, a professor at France's National Veterinary School of Alfort, who led the French study, said that the researchers used two types of dogs — search and rescue dogs, as they can sniff sweat, and explosive detection dogs, because they're often used at airports to find bomb ingredients. Dogs may very well be as good as PCR tests, said Dominique, but the goal, he added, is not to replace these tests with canines.
In France, the government gave the green light to train hundreds of disease detection dogs and deploy them in airports. "They will act as mass pre-test, and only people who are positive will undergo a PCR test to check their level of infection and the kind of variant," says Dominique. He thinks the dogs will be able to decrease the amount of PCR testing and potentially save money.
Since the accuracy rate for bio-detection dogs is fairly high, scientists think they could prove to be a quick diagnosis and mass screening tool, especially at ports, airports, train stations, stadiums, and public gatherings. Countries like Finland, Thailand, UAE, Italy, Chile, India, Australia, Pakistan, Saudi Arabia, Switzerland, and Mexico are already training and deploying canines for COVID-19 detection. The dogs are trained to sniff the area around a person, and if they find the odor of COVID-19 they will sit or stand back from an individual as a signal that they've identified an infection.
While bio-detection dogs seem promising for cheap, large-volume screening, many of the studies that have been performed to date have been small and in controlled environments. The big question is whether this approach work on people in crowded airports, not just samples of shirts and socks in a lab.
"The next step is 'real world' testing where they [canines] are placed in airports to screen people and see how they perform," says Anna Durbin, professor of international health at the John Hopkins Bloomberg School of Public Health. "Testing in real airports with lots of passengers and competing scents will need to be done."
According to Butlin of Medical Detection Dogs, scalability could be a challenge. However, scientists don't intend to have a dog in every waiting room, detecting COVID-19 or other diseases, she said.
"Dogs are the most reliable bio sensors on the planet and they have proven time and time again that they can detect diseases as accurately, if not more so, than current technological diagnostics," said Butlin. "We are learning from them all the time and what their noses know will one day enable the creation an 'E-nose' that does the same job – imagine a day when your mobile phone can tell you that you are unwell."
These doctors have a heart for recycling
This is part 3 of a three part series on a new generation of doctors leading the charge to make the health care industry more sustainable - for the benefit of their patients and the planet. Read part 1 here and part 2 here.
One could say that over 400 people owe their life to the fact that Carsten Israel fell in love. Twenty years ago, as a young doctor in Frankfurt, Germany, he began to court an au pair from Kenya, Elisabeth, his now-wife of 13 years with whom he has three children. When the couple started visiting her parents in Kenya, Israel wanted to check out the local hospitals, “just out of professional curiosity,“ says the cardiologist, who is currently the head doctor at the Clinic for Interior Medicine in Bielefeld. “I was completely shocked.“
Often he observed there were no doctors in the E.R.s, and hte nurses could render only basic first aid. “When somebody fell into a coma, they fell into a coma,“ Israel remembers. “There weren’t even any defibrillators to restart a patient’s heart,” while defibrillators are standard equipment in most clinics in the U.S. and Europe as lifesaving devices. When Israel finally visited the largest and most modern hospital in Nairobi, he found it better equipped but he learned that its services were only available to patients who could afford them. The cardiologist there had a drawer full of petitions from patients with heart ailments who couldn’t afford lifesaving surgery. Even two decades ago, a pacemaker cost $5,000 in Kenya, which made it unaffordable for most Kenyans who earn an average of $600 per month.
Since 2003, Israel and a team of two doctors and two nurses visit Kenya and Zambia once or twice a year to implant German pacemakers for free. Notably, the pacemakers and defibrillators Israel exports to Africa would end up in the landfill in Germany. Clinics have to pay for specialized services to dispose of this medical equipment. “In Germany, I could go to jail if I used a defibrillator that is one day past its expiration date,“ Israel says, “but in Kenya, people don’t have the money for the cheapest model. What nonsense to throw this precious medical equipment away while people in poorer countries die because they desperately need it.“
Israel works at the breakpoint between the laws in a wealthy country like Germany and the reality in the global South. The U.S. and most European countries have strict laws that ban the reuse of medical implants and enforce strict expiration dates for medical equipment. “But if a pacemaker is a few days past its expiration date, it still works perfectly fine,“ Israel says. “And it also happens that we implant a pacemaker and five months later it turns out that the patient needs a different kind. Then we replace it and we’d have to trash the first one in Germany, though it could easily run another 12 years.“
“If we get this right, we have lots of devices we can implant, hips and knees, etcetera. Where this will lead is limitless," says Eva Kline Rogers, the program coordinator for My Heart, Your Heart.
Israel has been collecting donations of pacemakers and defibrillators from manufacturers but also from other doctors and from funeral homes for his nonprofit Pacemakers for East Africa since 2003. Most funeral homes in the U.S. and Europe are legally obliged to remove pacemakers from the dead before cremation. “Most pacemakers survive their owners,“ says Israel. He sterilizes the pacemakers and finds them a new life in East Africa. Studies show that reused pacemakers carry no greater risk for the patients than new ones.
In the U.S., University of Michigan professor Thomas Crawford heads up a similar initiative, My Heart, Your Heart. “Each year 1 to 2 million individuals worldwide die due to a lack of access to pacemakers and defibrillators,” the organization notes on its website. The nonprofit was founded in 2009, but it took four years for the doctors to get permission from the FDA to export pacemakers. Since receiving permission, the organization has sent dozens of devices to the Philippines, Haiti, Venezuela, Kenya, Sierra Leone and Ukraine. “We were the first doctors ever to implant a pacemaker in Sierra Leone in 2018,” says Crawford, who has traveled extensively to most of the recipient countries.
Even individuals can donate their pacemakers; the organization offers a prepaid envelope. “My mother recently passed and she donated her device,” says Tina Alexandris-Souphis, one of the doctors at University of Michigan who collaborates on My Heart, Your Heart. The organization works with World Medical Relief and the U.K. based charity Pace4Life to maintain a registry of the most urgent patients and send devices to where they are needed the most.
My Heart, Your Heart is also conducting a randomized controlled trial to provide further evidence that reused pacemakers pose no additional risk. “Our vision is that we establish this is safe and create a blueprint for organizations around the world to safely reuse these devices instead of them being thrown in the trash,” says Eva Kline Rogers, the program’s coordinator. “If we get this right, we have lots of devices we can implant, hips and knees, etc. Where this will lead is limitless.” She points out that in addition to receiving the donated devices, the doctors in the global South also benefit from the expertise of renowned cardiologists, such as Crawford, who sometimes advise them in complex cases.
And Adrian Baranchuk, a Canadian doctor at the Kingston General Hospital at the Queen’s University, regularly travels through South America with his “cardiology van” to help villagers in remote areas with heart problems.
Israel says that he’s been accused of racism, in thinking that these pacemakers are suitable for those in the global South - many of whom are people of color - even though officials in wealthier countries consider them to be trash. The cardiologist counters such criticism with stories about desperate need of his patients. At his first medical visit to Nairobi that he organized with a local cardiologist, six patients were waiting for him. “In Germany, they would all be considered emergencies,” Israel says. One eighty-year old grandmother had a heartrate of 18. “I’ve never before seen anything like this,” Israel exclaims. “At first I thought I couldn’t find her pulse before I realized that her heart was only beating once every three seconds.” After the surgery, she got up, dressed herself and hurriedly packed her bag, explaining she had a ton of work to accomplish. Her family was in disbelief, Israel says. “They told me she had been bedridden for five years because as soon as she tried to get up she would faint.”
Israel has been accused of racism, in thinking that these pacemakers are suitable for those in the global South even though they're considered to be trash by officials in wealthier countries. The cardiologist counters such criticism with stories about desperate need of his patients.
Carsten Israel
The hospital in Nairobi where Israel conducts the surgeries, charges patients $200 for the use of its facilities. If patients can’t afford that sum, Israel will pay it from the funds of his nonprofit. For some people, $200 far exceeds their resources. Once, a family from the extremely poor Northern region of Kenya told him they couldn’t afford the $3 for the bus ride to Nairobi. Israel suspected this was a pretense because they were afraid of the surgery and agreed to reimburse the $3, “but when they came, they were wearing rags and were so rail-thin, I understood that they really needed every cent they had for food.”
Israel is a renowned cardiologists in Germany. And yet, he considers his work in East Africa to be particularly meaningful. “Generally, most patients in Germany will get the treatment they need,” he says, “and I never before experienced that people have an illness that is easily curable but simply won’t be treated.” He also feels a heavy responsibility. Many patients have his personal cell phone and call him when they have problems or good news about how they’re doing.
Some of those progress reports come much faster than in Israel’s home country. Before he implanted a pacemaker in a tall Massai in Kenya, the man had been picked on by his family because he wouldn’t help much with the hard work on the family peanut farm. “When I examined him, he had a pulse of 40,” Israel says. “It’s a miracle he was even standing upright, let alone hauling heavy bags.” After the surgery, Israel advised his patient to stay the night for observation, but the patient couldn’t wait to leave. Two hours later, he returned, covered in sweat. He’d been running sprints with his brothers to test the new device. Israel shakes his head. In Germany, it would be unthinkable for a patient to engage in athletics immediately after surgery. But the patient was exuberant: “I was the fastest!”
The success stories are notable partly because the challenges remain so steep. In Zambia, for instance, there is a single cardiologist; she determined to become one after losing her younger sister to an easily curable heart disease. Often, the hospitals not only lack pacemakers but also sterile surgery equipment, antibiotics and other essential material. Therefore, Israel and his team import everything they need for the surgeries, including medication. If necessary, they improvise. “I’ve done surgery with a desk lamp hanging from the ceiling by threads,” Israel says. He already knows that he will need to return to Kenya in six months to replace the pacemaker of one of his patients and replace the batteries in others. If he doesn’t travel, lives are at risk.These technologies may help more animals and plants survive climate change
This article originally appeared in One Health/One Planet, a single-issue magazine that explores how climate change and other environmental shifts are making us more vulnerable to infectious diseases by land and by sea - and how scientists are working on solutions.
Along the west coast of South Florida and the Keys, Florida Bay is a nursery for young Caribbean spiny lobsters, a favorite local delicacy. Growing up in small shallow basins, they are especially vulnerable to warmer, more saline water. Climate change has brought tidal floods, bleached coral reefs and toxic algal blooms to the state, and since the 1990s, the population of the Caribbean spiny lobster has dropped some 20 percent, diminishing an important food for snapper, grouper, and herons, as well as people. In 1999, marine ecologist Donald Behringer discovered the first known virus among lobsters, Panulirus argus virus—about a quarter of juveniles die from it before they mature.
“When the water is warm PaV1 progresses much more quickly,” says Behringer, who is based at the Emerging Pathogens Institute at the University of Florida in Gainesville.
Caribbean spiny lobsters are only one example of many species that are struggling in the era of climate change, both at sea and on land. As the oceans heat up, absorbing greenhouse gases and growing more acidic, marine diseases are emerging at an accelerated rate. Marine creatures are migrating to new places, and carrying pathogens with them. The latest grim report in the journal Science, states that if global warming continues at the current rate, the extinction of marine species will rival the Permian–Triassic extinction, sometimes called the “Great Dying,” when volcanoes poisoned the air and wiped out as much as 90 percent of all marine life 252 million years ago.
Similarly, on land, climate change has exposed wildlife, trees and crops to new or more virulent pathogens. Warming environments allow fungi, bacteria, viruses and infectious worms to proliferate in new species and locations or become more virulent. One paper modeling records of nearly 1,400 wildlife species projects that parasites will double by 2070 in the far north and in high-altitude places. Right now, we are seeing the effects most clearly on the fringes—along the coasts, up north and high in the mountains—but as the climate continues changing, the ripples will reach everywhere.
Few species are spared
On the Hawaiian Islands, mosquitoes are killing more songbirds. The dusky gray akikiki of Kauai and the chartreuse-yellow kiwikiu of Maui could vanish in two years, under assault from mosquitoes bearing avian malaria, according to a University of Hawaiʻi 2022 report. Previously, the birds could escape infection by roosting high in the cold mountains, where the pests couldn’t thrive, but climate change expanded the range of the mosquito and narrowed theirs.
Likewise, as more midge larvae survive over warm winters and breed better during drier summers, they bite more white-tailed deer, spreading often-fatal epizootic hemorrhagic disease. Especially in northern regions of the globe, climate change brings the threat of midges carrying blue tongue disease, a virus, to sheep and other animals. Tick-borne diseases like encephalitis and Lyme disease may become a greater threat to animals and perhaps humans.
"If you put all your eggs in one basket and then a pest comes a long, then you are more vulnerable to those risks," says Mehroad Ehsani, managing director of the food initiative in Africa for the Rockefeller Foundation. "Research is needed on resilient, climate smart, regenerative agriculture."
In the “thermal mismatch” theory of wildlife disease, cold-adapted species are at greater risk when their habitats warm, and warm-adapted species suffer when their habitats cool. Mammals can adjust their body temperature to adapt to some extent. Amphibians, fish and insects that cannot regulate body temperatures may be at greater risk. Many scientists see amphibians, especially, as canaries in the coalmine, signaling toxicity.
Early melting ice can foster disease. Climate models predict that the spring thaw will come ever-earlier in the lakes of the French Pyrenees, for instance, which traditionally stayed frozen for up to half the year. The tadpoles of the midwife toad live under the ice, where they are often infected with amphibian chytrid fungus. When a seven-year study tracked the virus in three species of amphibians in Pyrenees’s Lac Arlet, the research team found that, the earlier the spring thaw arrived, the more infection rates rose in common toads— , while remaining high among the midwife toads. But the team made another sad discovery: with early thaws, the common frog, which was thought to be free of the disease in Europe, also became infected with the fungus and died in large numbers.
Changing habitats affect animal behavior. Normally, spiny lobsters rely on chemical cues to avoid predators and sick lobsters. New conditions may be hampering their ability to “social distance”—which may help PaV1 spread, Behringer’s research suggests. Migration brings other risks. In April 2022, an international team led by scientists at Georgetown University announced the first comprehensive overview, published in the journal Nature, of how wild mammals under pressure from a changing climate may mingle with new populations and species—giving viruses a deadly opportunity to jump between hosts. Droughts, for example, will push animals to congregate at the few places where water remains.
Plants face threats also. At the timberline of the cold, windy, snowy mountains of the U.S. west, whitebark pine forests are facing a double threat, from white pine blister rust, a fungal disease, and multiplying pine beetles. “If we do nothing, we will lose the species,” says Robert Keane, a research ecologist for the U.S. Forest Service, based in Missoula, Montana. That would be a huge shift, he explains: “It’s a keystone species. There are over 110 animals that depend on it, many insects, and hundreds of plants.” In the past, beetle larvae would take two years to complete their lifecycle, and many died in frost. “With climate change, we're seeing more and more beetles survive, and sometimes the beetle can complete its lifecycle in one year,” he says.
Quintessential crops are under threat too
As some pathogens move north and new ones develop, they pose novel threats to the crops humans depend upon. This is already happening to wheat, coffee, bananas and maize.
Breeding against wheat stem rust, a fungus long linked to famine, was a key success in the mid-20th century Green Revolution, which brought higher yields around the world. In 2013, wheat stem rust reemerged in Germany after decades of absence. It ravaged both bread and durum wheat in Sicily in 2016 and has spread as far as England and Ireland. Wheat blast disease, caused by a different fungus, appeared in Bangladesh in 2016, and spread to India, the world’s second largest producer of wheat.
Insects, moths, worms, and coffee leaf rust—a fungus now found in all coffee-growing countries—threaten the livelihoods of millions of people who grow coffee, as well as everybody’s cup of joe. More heat, more intense rain, and higher humidity have allowed coffee leaf rust to cycle more rapidly. It has grown exponentially, overcoming the agricultural chemicals that once kept it under control.
To identify new diseases and fine-tune crops for resistance, scientists are increasingly relying on genomic tools.
Tar spot, a fungus native to Latin America that can cut corn production in half, has emerged in highland areas of Central Mexico and parts of the U.S.. Meanwhile, maize lethal necrosis disease has spread to multiple countries in Africa, notes Mehrdad Ehsani, Managing Director for the Food Initiative in Africa of the Rockefeller Foundation. The Cavendish banana, which most people eat today, was bred to be resistant to the fungus Panama 1. Now a new fungus, Panama 4, has emerged on every continent–including areas of Latin America that rely on the Cavendish for their income, reported a recent story in the Guardian. New threats are poised to emerge. Potato growers in the Andes Mountains have been shielded from disease because of colder weather at high altitude, but temperature fluxes and warming weather are expected to make this crop vulnerable to potato blight, found plant pathologist Erica Goss, at the Emerging Pathogens Institute.
Science seeks solutions
To protect food supplies in the era of climate change, scientists are calling for integrated global surveillance systems for crop disease outbreaks. “You can imagine that a new crop variety that is drought-tolerant could be susceptible to a pathogen that previous varieties had some resistance against,” Goss says. “Or a country suffers from a calamitous weather event, has to import seed from another country, and that seed is contaminated with a new pathogen or more virulent strain of an existing pathogen.” Researchers at the John Innes Center in Norwich and Aarhus University in Denmark have established ways to monitor wheat rust, for example.
Better data is essential, for both plants and animals. Historically, models of climate change predicted effects on plant pathogens based on mean temperatures, and scientists tracked plant responses to constant temperatures, explains Goss. “There is a need for more realistic tests of the effects of changing temperatures, particularly changes in daily high and low temperatures on pathogens,” she says.
To identify new diseases and fine-tune crops for resistance, scientists are increasingly relying on genomic tools. Goss suggests factoring the impact of climate change into those tools. Genomic efforts to select soft red winter wheat that is resistant to Fusarium head blight (FHB), a fungus that plagues farmers in the Southeastern U.S., have had early success. But temperature changes introduce a new factor.
A fundamental solution would be to bring back diversification in farming, says Ehsani. Thousands of plant species are edible, yet we rely on a handful. Wild relatives of domesticated crops are a store of possibly useful genes that may confer resistance to disease. The same is true for livestock. “If you put all your eggs in one basket and then a pest comes along, then you are more vulnerable to those risks. Research is needed on resilient, climate smart, regenerative agriculture,” Ehsani says.
Jonathan Sleeman, director of the U.S. Geological Survey National Wildlife Health Center, has called for data on wildlife health to be systematically collected and integrated with climate and other variables because more comprehensive data will result in better preventive action. “We have focused on detecting diseases,” he says, but a more holistic strategy would apply human public health concepts to assuring animal wellbeing. (For example, one study asked experts to draw a diagram of relationships of all the factors affecting the health of a particular group of caribou.) We must not take the health of plants and animals for granted, because their vulnerability inevitably affects us too, Sleeman says. “We need to improve the resilience of wildlife populations so they can withstand the impact of climate change.”