In early 2022, as the Omicron variant of the novel coronavirus raged across the country, Seema Rakudawala was in Pittsburgh putting together plans to open an all-new daycare. She found the perfect facility and signed a pile of paperwork. She was assembling a jumble of stuffed animals, puzzles and toys. It was the perfect setting, “something I’ve dreamed of for years,” said Emory University virologist Rakudawalla. When she welcomed her first attendees to her institution later that spring, she couldn’t help but puff up her chest with her pride. Among them were 5 juvenile ferrets, including 1 intentionally infected with influenza.
In the months that followed, Rakudawala and colleagues watched groups of ferrets ping-pong the flu virus back and forth as they flitted, wrestled and frolic in communal playpens. The researchers carefully recorded the ferrets’ movements. They focused on the surfaces and other animals each touched. Their early findings, now in preparation for publication in a scientific journal, studied how the influenza virus spreads most efficiently not only among ferrets but also among human children in a population environment. can help people figure it out.
There are many ways the influenza virus spreads, including aerosols, droplets, face-to-face contact, and contaminated surfaces. But the heart of the flu epidemic remains “almost a black box,” says University of Michigan epidemiologist Aubrey Gordon. Despite decades of research, “we don’t really know the relative importance of each potential route.” and may even one day design flu prevention for real day care.
Ferrets have long been the “gold standard for influenza transmission and transmission,” said Nicole Lockey, an environmental engineer at Duke University who led the camel wall experiments.The structure of the airways in animals is strikingly similar to ours, unlike most labs mouse or rat, ferret They are more likely to catch or transmit the flu virus, and may even develop the same coughing and sniffling symptoms that many humans have. However, most influenza infection experiments with ferrets are still confined to anthropogenic settings. In other words, pairs of animals are placed in small cages with partitions between them, and scientists watch them continue to suck each other’s air for days, even weeks. This is not how animals infect each other in the wild, nor how human spread occurs. “Beyond the hole-in-the-wall, we don’t see him interacting with each other for the full 48 hours,” Rocky told me.
A giant playpen equipped with toys, an air sampler and a video camera isn’t exactly a “playpen”. Nature Ferret habitat. But this setup takes advantage of many of the mischievous instincts of animals. Domesticated for thousands of years, ferrets “are a very playful species and love to be social,” said Alice Dancer, an animal welfare researcher at the Royal Veterinary College of London. As such, they are excellent models not only for influenza transmission, but also for influenza transmission among others. The kidswho seems to be Selection subject driver of the outbreak. At day care, ferrets fight over toys, climb on playground equipment, and eat stuffed snakes. They chase each other around and when they hide, they turn into a big pile and take a nap. They exchange affectionate sniffles, babbles, and small playful bites. All interactions represent potential transfer events. So are the surfaces they touch and the shared pocket of air they all breathe.
The researchers have already collected some results, and Rakudawala said it “has changed the way we think about infection a little bit.” In one early experiment, when they huddled an infected animal with four uninfected animals, they surprisingly found the ferret infected. Even if only slightly The ‘donor’ who had direct contact with influenza was the only ‘recipient’ who became ill in that room. Video footage showed the newly ill recipient imitated everything the donor did, including chewing the chew toy, rolling the ball and swiping the surface, Rakudawala said. It seemed counterintuitive until it was revealed. It was as if the first ferret left a trail of infectious crumbs that the second ferret sniffed out. If the findings apply to other experiments the researchers are currently analyzing, Rocky said, contaminated surfaces, or fomites, could play an unexpected role in virus transmission.
Another of the team’s early findings illustrates a similar concept. When the researchers increased the ventilation of ferret nurseries to remove airborne viral particles, they found that the same proportion of uninfected ferrets eventually became infected with the virus. This was disappointing, but not entirely shocking given how legged ferrets, and children for that matter, interact with other animals and their surroundings. There was no problem even if the air in the room changed more than once every 3 minutes. As ferrets ran around the room, researchers found viral particles on the walls of toys, treats and playpens.
Ventilation was not completely wasted. The researchers found that increased air exchange did appear to reduce the concentration of influenza genetic material in the air, slowing the onset of disease in ferrets infected under such conditions. Shedding Rakudawala thinks the viral effect is a hint that they may have received a lower dose of infection. In humans, it could result in less severe disease, but that needs to be confirmed, Gordon told me.
Whatever results the Rocky and Camel Wall ferret findings may have for human daycares may not necessarily apply to other facilities. In offices, hospitals, and even schools for older children, people generally have much less contact with each other and are much more savvy about hygiene. Plus, adults’ bodies aren’t built like children’s, says epidemiologist Cecil Vibou of the National Institutes of Health’s Fogerty International Center.their respiratory tract bigger, stronger and more evolved-and some experiments For at least some respiratory viruses, the results suggest that exhaled aerosols may be more infectious in older people and in larger people. For adults, ventilation can be even more important.
Camelwalla and her colleagues are still evaluating other interventions that may be more effective for ferrets and, ultimately, children. Humidifiers, air purifiers, targeted cleaning, and even keeping some parts of the playpen from being too crowded. (They don’t plan to experiment with hand washing or masking. Imagine the difficulty of strapping an N95 to a ferret’s face.) We are also considering whether to do so (as her team proved). Inactivates influenza virus within minutes— may play a protective role.
But everything that happens in a ferret’s playpen is still tricky. “It’s still an animal model, after all,” Bibou told me. Although there are many similarities between a ferret’s airway and ours, their small nose and nose shape can affect how they cough and sneeze. And the researchers have yet to study the spread of infection among ferrets who already have immunity to the flu (some daycare participants do). Ferrets are also more prone to chewing, wrestling, and defecating wherever they please than the average (potty-trained) child.
Still, Rakudawala is mostly happy with how childish ferrets are. They are affectionate and mischievous. They look bubbling with energy and cheers. After discovering that the air-sampling robot placed at the center of the daycare was mobile, some ferrets began riding it. While watching and sharing the footage at the conference, Rakudawala received the following feedback over and over again. oh yeahparents tell her. So do my kids.
