It’s a busy Monday morning at Medical Detection Dogs. Most of the dogs have filed in for their day of work, dropped off by their doting foster parents. They wag around, greeting one another, sniffing fore and aft in slow circles as if catching up after the weekend.
Mornin’, Marlowe.
Mornin’, Bumper.
Have a good weekend, did ya? From the aroma back here I’d say you had steak last night!
Oh ho ho, don’t tell the folks! I grabbed a bit of gristle from the bin when the missus wasn’t looking.
Good dog! Looking forward to another week of sniffing urine and getting treats for it?
You bet! How could I not? It’s like taking candy from a baby. Not that I’ve done that—recently.
Excuse me, here comes Karry. She smells like dog shampoo, poor girl. See you round the scent room?
Not if I see you first!
The watercooler communications die down as the dogs are called to practice their skills or wait their turn or go for walks. On this brisk November day, the prostate-cancer-detection dogs are the first to get to work in the large detection room. They pad around the scent wheel, alerting correctly almost every time to the urine samples from men with prostate cancer. Just as important, they don’t alert if there is no prostate cancer sample. Marlowe, Karry, Florin, Midas, and Jobi seem to have this down to a science, which is good, because that’s what it’s supposed to be.
Next up are the dogs I’m here to see. They’re part of a proof-of-principle study to determine if dogs can detect the bacteria Pseudomonas aeruginosa. These organisms are fairly ubiquitous in the environment. They’re usually found in moist places like sinks and soil and vegetation. For healthy people, P. aeruginosa (which we will refer to simply as Pseudomonas from now on) doesn’t usually present much risk.
But for people with weakened immune systems, Pseudomonas can be deadly. It’s easily spread in hospitals and long-term health care facilities, which are full of people with compromised immune systems.
Infection with Pseudomonas can be a lifelong struggle for those with cystic fibrosis, a serious genetic disease affecting at least seventy thousand people worldwide. It causes fluids like mucus, sweat, and digestive enzymes, which are normally smooth and thin, to be thick and sticky. The thickened mucus can trap microorganisms in the lungs, which can lead to chronic infections and impede lung function. It also can cause severe damage to the digestive system, liver, and other organs.
By adolescence or young adulthood, the majority of cystic fibrosis patients are infected with Pseudomonas. Normally people with wet coughs can produce sputum to be tested for the bacteria, but it’s harder for people with cystic fibrosis. Testing on babies and young children usually involves using a cough swab, but it’s not a reliable technique. Even if sputum is produced, culturing it and identifying it can take several days, which can lead to delays in treatment and possible cross-infection.
Jane Davies, MD, professor of pediatric respirology and experimental medicine at Imperial College London and honorary consultant in pediatric respiratory medicine at Royal Brompton & Harefield NHS Foundation Trust, specializes in cystic fibrosis in children. She’d like to see monitoring for Pseudomonas infections that can be done frequently and rapidly, and doesn’t necessarily rely on sputum, so infections can be caught in the early stages.
She and her colleagues are working on several high-tech ways to detect Pseudomonas, including mass spectrometry, cell-free biosensors, and optoelectronics. “But this machinery stuff is quite difficult,” she said at a talk at Imperial College. (She regretfully declined speaking with me for the book because she was nervous about doing anything that could jeopardize publication of the study you’ll read about shortly. That’s why I’m quoting her from videos and getting background information from other sources.)
While waiting for technology, they decided to see if there was a less high-tech approach for reliably and quickly detecting Pseudomonas. “We have begged the question, ‘Is nature already able to help us in a way that this technology is trying to reinvent?’”
Cue the dogs.
Pseudomonas produces volatile organic compounds that some say have distinctive odors. In small samples provided by patients, humans can’t smell it. But when grown on bacteriological media where the bugs can proliferate, it has been described as smelling like everything from flowers to grape juice to fresh tortillas. The idea is that if people can smell it in concentration, maybe dogs can smell it at normal levels.
If the dogs at Medical Detection Dogs can easily identify the bacteria, this could lead to rapid screening for Pseudomonas in the patients who need fast diagnoses. Patients, especially those who have a hard time producing sputum, could send in coughed-on tissues and breath samples on a fairly regular basis for inspection by bacteria-sniffer dogs. Dr. Davies told the audience it could be an inexpensive way to keep on top of infections.
Working with dogs has been a refreshing change for Dr. Davies and her staff. “It’s a bit of a laugh. We’re having a good time doing it, and it may come to something.”
A short black Lab named Mason is the first in the Pseudomonas-detection lineup today. Although Mason is only two years old, he’s already on his third career. He was trained to be a guide dog, but that didn’t work out. When he came to Medical Detection Dogs, he was trained as an assistance dog, but that didn’t work out either. He is drooling a lot today. Maybe that has something to do with it. But he seems to have found his calling as a medical detection dog.
He’s the new guy on the team and is just getting familiar with the scent of Pseudomonas. A trainer wearing latex gloves kneels at dog level and holds out a vial containing a sterile sample of the bacteria. All Mason has to do is approach it and give it a nice, close sniff. As soon as he does, she presses the clicker and tells him “Good!” in a high and happy voice. That’s only part of his paycheck, though. Being a Lab, he likely prefers the other part, where she skitters a few tiny treats a couple of feet across the floor. He chases after them and gives them a couple of chomps before he notices she’s holding out the magic vial again. A string of drool hangs from a jowl.
Sniff. Click. “Good!” Skitter. Chomp.
He’s got this. As he aces it time after time, I spot a black-and-white springer spaniel–ish dog lying down on the other side of a glass observation wall, watching Mason. I learn that her name is Freya, and she’s in training to be a malaria-detection dog. She doesn’t have anything to do today. Her detection happens on other days, but she’s here anyway because she lives with one of the trainers.
Even though she could be hanging with other dogs during their downtime, or meandering around the offices and being adored, she’s chosen to repose on the burgundy carpet on the other side of the glass. She lies in a splash of striped sunlight shining through the blinds of a window in the training lab. Her eyes are fixed on Mason, a good fifteen feet away.
Sniff. Click. “Good!” Skitter. Chomp.
Freya is riveted, moving her head only if the skittering kibble goes farther than normal. She’s like a music teacher watching her student from afar during an audition, urging him on psychically, hoping he’ll perform as well as she knows he can.
Mason approaches the vial again, but this time he dips in for a whiff when he’s at least a foot away. He stands expectantly, waiting for his praise and his kibble. Not receiving it, he sits and takes on a serious demeanor. He looks at the trainer. She holds out the vial to give him another chance, but he just sits and stares at her.
Excuse me, ma’am, I believe you’re forgetting something?
She smiles and hides the vial under her arm. When she brings it back out, he’s on top of his game again, touching his nose to the rim and giving a sniff.
Click. “Good!” Skitter. Chomp.
A few more rounds and he’s done.
“Good job, Mason! Goooood boy!” she tells him.
Freya watches him leave the room. She rests her head on the carpet and closes her eyes.
Lizzie is next on the roster. She’s part bearded collie, part springer spaniel, and today she is also part Ping-Pong ball. She runs into the detection room and skids to a stop at the feet of her trainer. She sits and looks up at him, squeaking some excited barks. The trainer stands calmly and looks back at her. She squeaks some more, then canters to one side of the room and back.
“She’s always like this at the start of the day,” he says. “Plus it’s Monday, so she’s raring to go. I just let her get it out of her system. She needs to know that she doesn’t always have to get right to work in this room.”
Lizzie runs toward the observation wall and glances at Freya, who is now standing up, staring at her, her mouth slightly agape.
Lizzie is six years old, so this isn’t puppy energy. She was trained as a bedbug-detection dog elsewhere, but as with Mason’s previous gigs, it didn’t work out. “She’s impulsive,” says the trainer. “We’re working on focusing her. She’s got a great nose once she settles in.”
Her training today is a little more advanced than Mason’s. Whereas he just had to head a few feet over to a trainer who was holding a vial, Lizzie is supposed to enter the room and walk about seven feet to a short metal stand containing a vial with the Pseudomonas. Once there, she should sniff it and alert calmly. That’s the idea, anyway.
The first few times she does it, she runs in, smells the sample, and slams the device so hard with her paw that it moves a few feet.
“Try to work on that paw action not happening,” another trainer advises Lizzie’s trainer du jour from the other side of the room.
Freya is still standing and watching through the observation window. Her upper lip has somehow gotten caught up on her gum and is stuck in a curled position. She’s looking pretty judgy.
Lizzie tries again. This time she whacks at the sample with both paws and it moves farther toward the center of the room.
“Lizzie, no,” the trainer says, and points for her to leave the room.
The next time she enters, she runs to the device, sniffs, and sits.
Click. “Good girl!”
Treat. Wag!
After a couple of successes, she’s on a roll. She sits and stares at the vial. She looks like Nipper, the dog listening intently to the gramophone in the famous painting His Master’s Voice. Only instead of hearing a gramophone, she’s smelling a Gram-negative bacteria.
After a few perfect rounds, Lizzie takes to vigorously licking the vial each time, as if it’s an ice cream cone.
“That’s probably enough for now,” the other trainer says.
Out jogs Lizzie, and in saunters Oakley, a large black Lab with a red collar. Compared to normal dogs, he is calm. Compared to Lizzie, you have to resist the urge to check his pulse.
Oakley is regal. Oakley is confident. Oakley is da bomb.
He walks over to a row of four detection stands. Three contain controls (different bacteria common to cystic fibrosis and an uninfected sample); one contains the Pseudomonas. Or maybe they’re all controls with no Pseudomonas. Oakley doesn’t know. But he knows if he alerts to the right one, or if he doesn’t alert if there’s no Pseudomonas, he’ll get a reward.
The detection stands are next to the observation wall, where Freya is now lying with her head on her paws, facing the glass. She looks like a fangirl.
Oakley walks calmly to the first stand, sniffs, then on to the second stand, sniffs, then the third stand, sniffs, keeps his nose there, and slowly wags his tail.
Even his alert is calm.
Click. “Yesssss! Good boy!” Treat. Chomp.
Without taking her eyes off him, Freya stands up to watch the master at work.
He is perfect every time.
When he’s done, Freya stretches. She leaves her post and walks toward the entrance to the detection room, where she waits for Oakley.
There’s another dog on the team, but I’m told he doesn’t like working in front of someone he doesn’t know. His name is Flint, and apparently he’s got the biodetection-dog equivalent of stage fright.
These four unique canine characters could make a significant difference in health outcomes for a vulnerable population.
Months after my visit to Medical Detection Dogs, the first phase of the study had been completed. Dr. Davies couldn’t talk about the results, but I learned what I could from a poster abstract that was presented at a conference.
Mason was too new to the project to be part of this trial, but he’ll be in on the next phase. The other three dogs each did extremely well in the double-blind trial.
Even Lizzie.
They each sniffed out two hundred samples in a double-blind externally supervised trial. A bar graph indicates that Oakley correctly detected 100 percent of the bacteria. (Freya is surely even more smitten now.) Flint the Shy wasn’t far behind. Lizzie the Hyper dragged down the success rate of the team a little with a detection rate just under 90 percent. But still, quite impressive.
The next phase of the research will involve exhaled breath and coughed-on tissues. Gus, who is an aficionado of used tissues, would be a natural for this job. Alas, he lives too far away, so he’ll sit this one out and let Lizzie and her friends handle it.
Researchers have only recently begun to explore the role of dogs as rapid, inexpensive, noninvasive means of detecting some of the most dangerous microscopic bad boys—pathogens and parasites. The science is in its infancy. Most of the research has focused on whether dogs can even detect these invisible dangers. Proof-of-principle studies so far have been demonstrating they can.
The research doesn’t usually make headlines the way studies about cancer-detection dogs do. But the potential benefits could be even more far-reaching: Rapid discovery of a virus or harmful bacteria could stop an infectious disease from spreading to a wide population, or dramatically reduce the waiting time for test results, leading to timely and possibly lifesaving treatment.
Researchers with the Canine Performance Sciences program at Auburn University recently showed that the odor of a virus is detectable by dogs. Not only did dogs recognize the virus among uninfected cell cultures, but they could discriminate between the target virus and two other viruses. This is pretty big news in the world of dogs and science. But maybe because the dogs were sniffing bovine viral diarrhea virus (BVDV) instead of something more dramatic that infects us—like the flu—reporters weren’t clamoring for interviews.*
Surely research showing that dogs can detect a notorious antibiotic-resistant superbug wouldn’t go without notice. It would be a pretty big deal if dogs could find something as harmful as methicillin-resistant Staphylococcus aureus (MRSA). MRSA is a highly contagious pathogen that’s often picked up during stays in hospitals and long-term health care facilities. The bacteria are resistant to many common antibiotics, and if the infection spreads to the heart, bloodstream, lungs, and bones, it can be deadly.
A couple of research teams have been investigating the possibility that dogs can detect MRSA’s volatile organic compound scents. Yet when Toronto researchers reported the results of a study showing that dogs can detect MRSA, and can even distinguish it from similar strains, the news didn’t go much further than the Journal of Hospital Infection.*
Fortunately, publicity is not what drives most researchers—or dogs. If other doctor dog discoveries inspire TV segments while the pathogen-pursuing pups only end up in a published paper, they don’t mind.
A study with exciting potential for practical application in the near future is also a study with one of the best understatements ever: “Sniffing urine is an innate behavior in dogs,” write the authors of a paper on canine detection of urinary tract infections, in the journal Open Forum Infectious Diseases.
Anyone who endures daily walks with a dog who stops frequently to read “pee-mail” can attest to this. Yes, sniffing urine is indeed innate. The paper discusses the reasons dogs do this, and amazingly, “to vex the person on the other end of the leash” is not among them. The main reason the authors give for dogs sniffing urine is identifying other dogs and their notable characteristics, including their fertility and health status.
It turns out that the canine fascination with urine may be a boon for humans. The authors write that dogs are predisposed to “exceptional accuracy in identifying disease in humans by sniffing urine samples.”
The study’s dogs, who were trained to identify urine samples for E. coli and three other types of bacteria (S. aureus, Enterococcus, and Klebsiella) in double-blinded conditions, correctly detected nearly 100 percent of the positive samples. Even when the samples were diluted with distilled water and contained very low bacterial counts, the dogs could sniff out the troubled waters. The authors suggest that dogs could provide early detection of urinary tract infections (UTIs).
UTIs are a common health problem, accounting for ten million visits to physicians every year in the United States. For most patients, they’re easily treated. But for some, especially the elderly and people with limited mobility because of neurological conditions, UTIs can lead to complications. If left untreated, they can rapidly become lethal.
The study suggests that highly trained future service dogs for those with, say, spinal cord injuries could do double duty. They could help their people with mobility, and they could also serve as UTI monitors. Early detection from a best friend who also steadies you out of bed, picks up your dropped phone, and helps you get up if you take a tumble? It doesn’t get much better than that.
Research continues.
Meanwhile, in Canada, a dog is already hard at work detecting another nasty bug. This bug isn’t in urine, but in another form of bodily waste that’s a real crowd pleaser in the canine world.
A black-and-white English springer spaniel named Angus may consider himself the luckiest doctor dog in the world. While other medical detection dogs busy themselves sniffing out cancer and diabetes and all manner of disorders, Angus spends his days sniffing for something close to the heart and soul of any self-respecting dog: feces. Or, as we’ll call it here because we are all friends: poop.
When Angus is working, it’s clear that this is a dog who would not trade his job for all the tennis balls at Wimbledon. With handler Teresa Zurberg on the other end of his bright orange leash, he zips and clips and wags and zags up and down the halls of Vancouver General Hospital. His quarry is poop, but not just any poop. It’s poop that contains the superbug Clostridium difficile, otherwise known as C. difficile, or more commonly (and more cool-sounding) C. diff.
My favorite description of C. diff comes from a museum dedicated to microbes, in Amsterdam.
Clostridium difficile is the black sheep in the Clostridia class. The other members are mostly useful intestinal bacteria which break down fibres in the gut, producing important nutrients for the cells in the intestine . . . The other intestinal bacteria usually keep C. difficile under their thumb but antibiotic use can get rid of these “good” bacteria. The Clostridium difficile spores are able to survive the antibiotic attack and can reproduce unchecked.
C. diff is a highly contagious and sometimes deadly bacteria. Its most common victims are people whose beneficial gut bacteria have been compromised by antibiotics. The main symptom of a C. diff infection is diarrhea—in severe cases, it’s miserably uncontrollable. If that’s not bad enough, it’s often accompanied by fever, abdominal pain, and rapid heartbeat—“immense suffering,” in the words of a former CDC director.* In the United States, C. diff causes half a million infections a year, and fifteen thousand to thirty thousand deaths.
Hospitals are a delectable environment for C. diff. They’re filled with sick people on antibiotics, and if a patient is infected and has diarrhea, the spores can easily be transferred from one person to another, or to objects common to hospitals—anything from bed rails to stethoscopes to remote controls. The rugged bug can live for months on surfaces and will happily travel from the hand of someone who touches the contaminated surface to its next victim, where the whole cycle of misery starts anew.
Angus’s job is to sniff out C. diff in the hospital environment before it has a chance to go on its next joyride from hand to mouth to gut. The C. diff he seeks has already traveled to places it shouldn’t be. His aim is to make it a one-way trip.
A photo badge identifying him as a hospital volunteer dangles from his blue harness emblazoned with the words “WORKING DOG.” As far as the hospital is concerned, he’s a volunteer. But anyone who sees Angus at work knows he is well compensated for plying his trade. Treats, a ball, praise—the paycheck varies, but he’s always happy and has never asked for a raise.
He whisks his way down the corridor of the fourteenth-floor medical unit, directed partly by Teresa but mostly following his own nose. You don’t realize how many devices have wheels in a hospital until you’re with a dog who smells all of them. A wheeled cart here, a wheeled contraption there, a wheelchair, a wheeled stool under a sink, a shelf on wheels, wheeled drawers known as isolation carts. He sniffs the wall, inhales at a plastic garbage can, inspects a laundry bag. He is trained to avoid contacting surfaces with his nose so he doesn’t end up with C. diff or other goodies on his snout.
Everyone wants to say hi to him, but he’s a dog on a mission. Visitors stop and watch. Staff members smile as he passes their stations. “Hi, Angus!” He looks up and wags but gets right back to it. He is vigilant and focused. Nothing will distract him.
Almost nothing. He spots a stuffed toy bear at one of the nurses’ stations. His eyes fix on it. He looks at Teresa, then the toy, then Teresa. His eyes seem wider than they were before, and there’s a pleading quality to them. His message is clear:
Can I have that please?
“No, that’s not yours, Angus.”
They move on. She gives him a “Good boy!” every time he sniffs something. They come to a metal cart with three shelves. It’s stationed between two patient rooms. The top shelf holds several boxes of disposable gloves. The next shelf down has a couple of folded patient gowns and something medical-looking in a plastic bag with white wires coming out of it. The lowest shelf contains two white mesh bags stuffed with yellow isolation gowns.
Angus sniffs the bags, sniffs under the cart, sniffs the side of the cart. His tail wags faster. He stares at Teresa. Then he sits. Hard. He stares at Teresa more. He wags harder. The floor is so smooth and shiny that his hind legs drift apart until they’re so far away from each other he can’t sit anymore. He stands and stares at Teresa and wags some more.
She leads him away. He looks incredulous. He stops and sits and stares at her. She pets him, tells him he’s a good boy, and explains to me that there’s a glove on the ground under the cart, and he probably just wants to get the glove. He follows her for a step, then sits again and stares at her. She pets him more and tells him they’ll come back.
They walk on and he jumps up on her legs. He really wants to tell her something. But they continue on their rounds.
As promised, in a couple of minutes they’re back at the cart. Angus sits and wags and stares again. He doesn’t stick his nose under the cart, where the crumpled glove hides. Teresa realizes it’s probably not the glove after all.
“GOOD boyyy!” she says with the enthusiasm of someone whose dog may have just thwarted a deadly outbreak.
Happy to have his discovery acknowledged, Angus trots away with her.
Teresa tells a couple of nurses about the location of the possible C. diff, and we head back to her office. She plays a little tug-of-war with him and gives him a couple of dog cookies.
When he’s done with his snack, I ask Angus a question while I pet his soft coat, which has the pattern and color scheme of Oreos crumbled in milk.
“What does C. diff smell like, Angus?”
He stretches and walks into his soft-sided kennel, where he curls up and promptly falls asleep. My question doesn’t seem to interest him, but Teresa jumps at the chance to describe it.
“It smells kind of like boiled bamboo shoots.”
I have no idea what boiled bamboo shoots smell like. They could smell like cotton candy for all I know.
“Be right back!”
She returns a minute later with a sealed jar. It contains a two-inch square of gauze. She explains that this gauze had been exposed in a different jar to the poop of someone with C. diff. The poop and the gauze coexisted, though didn’t touch, for twenty-four hours. So the gauze should have the odor—and only the odor—of C. diff. It’s what Angus trains on, partly because it’s not dangerous since it contains just the odor, not the spores, and partly because poop has so many variables.*
She unscrews the lid, and I lean in to take a whiff of C. diff.
I can say with confidence that it does not smell like cotton candy. I can also say with confidence that it’s one of the worst things I have ever smelled. I have a dog who rolls in seriously decayed animals when he gets the opportunity, so that’s really saying something. I have smelled ugly, and this is ugly.
It’s a nasty, sharp, acrid odor that jolts you to the depths of your sinuses. It creates almost a burning sensation, but that’s not quite it either. It’s impossible to describe the smell of true C. diff, but when you smell it, you know it’s something you want to avoid.
Many health care professionals say they can sniff out C. diff in a patient even before the lab tests come back. Here are a couple of colorful descriptions from an online forum for nurses:
It smells like using an outhouse or J-John during 3 months of 110+ degree temperature days. It does not smell like normal poop; it smells like something that has been dead and laying in the hot sun with just a slight tang of poop smell . . .
To me it is like that rotten chicken meat smell, (like when you smell that chicken and go . . . “no way . . . can’t make this tonight! PUEWWWWWW”) mixed with baby diaper sweet smell (like when they are very young!), mixed with old blood smell. Once you smell it . . . you won’t forget!
And yet Angus is happy to find it. Ecstatic, actually.
As Teresa and I discuss the smelly superbug, I realize I’d just been petting a dog who sniffed possible C. diff in a hospital unit. Could he have rubbed against it? Probably not. Just in case, I fish out the bottle of Purell in my bag and squirt it onto my hands.
“Oh, sorry,” Teresa says, in the endearing way many Canadians say “sorry.” “Purell doesn’t really protect against C. diff.”
What?! Purell and other alcohol-based hand sanitizers boast that they kill 99.99 percent of common germs that cause illness. That’s a really large percentage. Like pretty much everything. When you see “99.99 percent,” you don’t think there’s going to be anything harmful in the remaining 0.01 percent. You don’t even think of that 0.01 percent. Maybe these sanitizers should say something like “Kills 99.99 percent of common germs that cause illness but NOT the superbug C. diff, which can make you really REALLY sick. Go wash your hands with soap and water—now!”
The journal Infection Control & Hospital Epidemiology confirms Teresa’s warning: “Alcohol is not effective against Clostridium difficile spores,” it states, and adds an example to drive home the point: “Residual spores are readily transferred by a handshake after use of ABHR.” (Alcohol-based hand rubs have their own acronym in certain circles.) The paper goes on to state that thorough hand washing is far more effective.
I excuse myself and wash my hands twice as long as usual. When I return, Teresa tells me, “Better safe than sorry. Believe me. You do NOT want C. diff.”
This sounds personal. Turns out it is. In 2013, Teresa had a leg wound that became septic, and the antibiotics she had to take depleted her beneficial bacteria. This left C. diff to colonize and proliferate.
She had it bad, with diarrhea four to five times an hour, necessitating diapers, much to her embarrassment. The infection also brought fever, pain, and chills. She spent five days in the hospital, and in the course of one week with C. diff lost twenty pounds.
“I almost died,” she says.
She finally got better—thanks, ironically, to antibiotics.
During her recovery her husband, Markus, ran across an article about a beagle in the Netherlands who was trained to sniff patients for C. diff. Teresa was a dog handler and trainer at the time, working with bomb- and drug-detection dogs in the private sector.
“Do you think you could train a dog to find C. diff in the environment?” he asked. Markus, a nurse working in Quality and Patient Safety for Vancouver Coastal Health, knew there were no fast, accurate ways to detect C. diff lurking in hospital settings.
“If it has a smell, I can train a dog to find it,” Teresa told him with conviction. Based on her bout with the bug, she was pretty sure that C. diff stinks in more ways than one.
She had recently acquired a pup named Angus and was planning to train him as a detection dog for a security job. He was in the right place at the right time. Markus and Teresa approached the health authority that oversees the Vancouver General Hospital with their idea.
“We thought they’d laugh us out of the room,” she says.
But the hospital liked their proposal of a pilot program. If it could help make the hospital environment safer, they were all for it. Teresa began training Angus. It took about a year because she was also working full-time as a cardiology technician. After double-blind validation/certification testing, the team became fully operational in the fall of 2016.
Angus has had a wildly successful early career. A study done in-house and published in 2017 in the Journal of Hospital Infection reported that his recognition of C. diff in containers was 100 percent (this is called sensitivity, you may remember from the cancer chapter), and he alerted to only 3 percent of negative samples as if they were positive (in other words, the specificity was 97 percent). During searches, his sensitivity was 80 percent (it has greatly improved since then, Teresa says) and specificity was 93 percent. And during clinical sweeps in a five-month period he was 100 percent on C. diff samples hidden for quality control.
The study concluded that “a dog can be trained to accurately and reliably detect C. difficile odour from environmental sources to guide the best deployment of adjunctive cleaning measures and can be successfully integrated into a quality infection control programme.”*
Angus has had more than five hundred alerts in his career. He’s been asked to assess several other hospitals either for outbreaks or to do baseline assessments. His finds have resulted in units and whole hospitals changing their protocols and procedures.
He used to frequently alert to staff lockers, for instance. It didn’t take long to figure out what was going on. Staff would put their work shoes in their lockers at the end of a shift. The shoes sometimes had C. diff contamination. When they arrived for their next shift, they’d take out their work shoes and put their personal effects—jackets, purses, lunch bags—into their lockers, setting up a scenario for cross-contamination.
The solution was simple; the units provided shoe racks for staff. No more shoes in the locker means no more locker alerts from Angus.
Occasionally Teresa comes across nurses telling her they don’t need a dog to tell them there’s C. diff—that they already can smell it. Her response: “I know you can smell C. diff, but can you tell me where exactly the spores are, and are you willing to crawl on your hands and knees to find it?”
End of discussion.
Some of Angus’s biggest fans are in the infection-control department at Vancouver General Hospital. Doctors there say there has been a “significant decrease” in C. diff since Angus started. A recent study found that C. diff rates have decreased in hospitals across Canada in the last several years thanks to better testing and more careful use of antibiotics. But there’s only one Angus, and he’s getting lots of credit for his hospital’s decrease.
When he detects C. diff, staffers clean the area using an ultraviolet light disinfection robot. But Angus has helped reduce C. diff in less tangible ways as well.
Just having him scour the hospital for C. diff seems to make staff more aware of the bacteria, explains Diane Roscoe, MD, head of the Division of Medical Microbiology and Infection Control at the hospital. They’re more careful because there’s a four-legged inspector who randomly sniffs his way through the hospital.
“Angus raises the bar,” Dr. Roscoe says. “The crew is so much more aware because of him. And the beauty is there’s no finger-pointing. He’s good in so many ways.”
As we sit discussing the virtues of Angus, Dr. Roscoe’s phone rings.
“Good news!” she tells Teresa. “They found a brown stain where Angus alerted this afternoon. They’re taking care of it.”
Teresa does a happy dance in her chair.
“Yes, I get excited about poop!” she tells me.
She’s in good company. She can’t wait to go tell Angus when we go back to her office.
In the Gambia, local health care workers recently collected urine, breath, and fingerpick blood samples from six hundred children in two schools and gave the children a pair of beige nylon ankle socks to wear for twenty-four hours. The socks were then cut lengthwise into four pieces that were packaged neatly into tiny plastic bags and shipped en masse to Medical Detection Dogs.
The baggies of sock pieces waited in drawers of a deep freezer as the organization assembled a team of dogs whose job would be sniffing the socks for a scent well-known to mosquitoes: the scent of someone infected with malaria.
A Labrador retriever named Sally and a Lab–golden retriever mix named Lexi were chosen for the initial team. If successful, the duo could help usher in a new way of preventing the spread of a scourge the Centers for Disease Control calls “one of the most severe public health problems worldwide.”
(Freya, the spaniel you may remember as the not-so-neutral observer during the Pseudomonas study, was to be on the original team, but it was decided she’d be trained for another phase of the study.)
Malaria is an infectious mosquito-borne disease that cuts a swath of illness and death in a wide band around the equator, but especially in Africa, which accounts for 90 percent of malaria victims. In 2016, the most recent year for which statistics were available, there were 216 million cases of malaria worldwide. To put it in perspective, that’s the population of the fifteen most populous US states. We’re talking everyone in Massachusetts, Arizona, Washington, Virginia, New Jersey, Michigan, North Carolina, Georgia, Ohio, Illinois, Pennsylvania, New York, Florida, Texas, and California.
Malaria claimed the lives of 445,000 people that year. The disease affects mostly young children and pregnant women. It’s a leading cause of illness and death in many developing countries.
As daunting as these figures are, they’re greatly improved from the previous decade. The CDC reports that malaria mortality has decreased by 45 percent, ‘‘leading to hopes and plans for elimination and ultimately eradication.” Governments and organizations around the world have been scaling up malaria-control interventions, including widespread distribution of bed nets and application of insecticides, as well as increased testing and treatment.
The Gambia is one of the countries that has seen a substantial decline in the disease, but a cross-sectional survey published in the Malaria Journal concluded that “current interventions are not sufficient to interrupt transmission . . . and new approaches need to be urgently evaluated . . . The Gambia offers an ideal setting to test new interventions aiming at interrupting malaria transmission.”
In 2016, the Bill & Melinda Gates Foundation—which has made eradicating malaria one of its top priorities—awarded a $100,000 grant for a joint collaboration of the canine kind.*
The initial study is simple in concept: to see if dogs can smell malaria. If this proves successful, dogs could one day be used for screening travelers entering malaria-free areas, much as airport dogs screen travelers for drugs or explosives or certain foods.
The dogs could also be used to sniff out malaria within communities in a much faster and less invasive way than current methods. Right now, malaria detection usually involves a finger-prick blood test that has to be evaluated in a laboratory.
Steve Lindsay, PhD, a public health entomologist at Durham University in northeast England, is the study’s lead investigator. He has worked in the Gambia regularly since the 1980s, devoting much of his career to developing malaria-control measures. He has high hopes for these doctor dogs without borders.
“Dogs could hugely accelerate efforts to completely wipe out this terrible disease once and for all,” says Dr. Lindsay.
When he learned that the Gates Foundation was looking for researchers to develop a noninvasive malaria diagnostic tool, he immediately thought of dogs. He has had dogs most of his life, although he is “now in the awful time between dogs” since the death of his Labrador retriever. And he’s been aware of the power of a dog’s nose for a long time. As a young man, he wanted to be a veterinarian and found a weekend job working with bloodhounds and taking them to shows to compete. Thanks to his travels, he’s also been screened by plenty of dogs at airports.
He invited fellow dog-lover and colleague James Logan, PhD, head of the Department of Disease Control at the London School of Hygiene & Tropical Medicine, to collaborate on the study. One of Dr. Logan’s fields of research is the potential odor change of people with malaria.
“Infection with malaria creates a human perfume that seems to make people more attractive to mosquitoes,” Dr. Logan says.
A brief lesson in malaria transmission might be handy to make sense of why this would be. When a mosquito infected with a parasite that causes malaria bites someone, the mosquito’s saliva transmits the parasite in a spore-like form directly into the person’s bloodstream. The parasites first invade the liver and grow and multiply there until they leave in a more mature stage of life to grow and multiply again, this time in red blood cells.
When a mosquito takes a blood meal from someone infected with the parasite, she’ll pick up some of these parasites, and they’ll also grow and multiply inside her. In ten to eighteen days, the parasites are in the sporozoite stage in the mosquito’s saliva. With her next blood meal, she’ll start the cycle again, infecting a new person (unless she happens to bite someone who already has malaria).
The parasite’s chances of spreading increase if mosquitoes are drawn to people who harbor the parasite. While earlier studies showed that those with malaria have a different smell and are more attractive to mosquitoes, a study co-led by Dr. Logan and published in 2018 zeroed in on chemicals that seem to attract mosquitoes.*
They found the main attractants were compounds called aldehydes, including heptanal, octanal, and nonanal, which easily evaporate and are used in perfume making. Perfumes using aldehydes—and some of the most popular perfumes do—are described as floral or fruity.
“The malaria parasite is very clever, manipulating the systems of the mosquito host and the human host,” Dr. Logan says. We can only hope the dogs will also be clever, using their noses to help manipulate the parasites into oblivion.
In the early phase of training, Sally and Lexi were alerting to something, but it wasn’t malaria: it was the difference between the odors of the two schools where the socks were worn and collected. The scent of the schools turned out to be stronger than the smell of the malaria. Once the researchers and the Medical Detection Dogs trainers realized this, they were more careful about how the samples were presented until the dogs got the hang of what they were supposed to be sniffing.
The dogs ended up with only 175 pair of socks out of the initial 600, so the sample size was far lower than the researchers and MDD had wanted, especially since only thirty pairs were positive for malaria. But Dr. Lindsay said they decided to be “über-careful” with the samples. “We needed to make sure the negatives were negative and the positive samples were positive. For this reason the positive samples were those where we could see malaria parasites down a microscope (not detected by PCR) and the negatives were those that were PCR-negative. PCR detects much lower parasite densities than does microscopy.” (PCR stands for “polymerase chain reaction.” It’s a technique for finding incredibly small pieces of DNA, and is frequently used for diagnosing infectious diseases, including malaria.)
The preliminary results were announced in late 2018. They made headlines around the world. Sally and Lexi detected 70 percent of the positive socks and 90 percent of the negative socks. Dr. Lindsay believes that if the sample size had been larger, the dogs would have done even better, but he says he considers these “excellent results” for the limited samples.
They’re now seeking funding for more research. They hope to eventually test dogs at ports of entry in sub-Saharan Africa. If the dogs chosen for the mission prove to be good at what they do, doctor dogs will enter a new stage in helping keep humans safe from hidden enemies: the world stage.