Amid widespread gaps in U.S. testing for H5N1, a type of bird flu, and with the detection of a second case among humans, scientists are turning to more creative ways to track the outbreak — particularly in human and animal feces.
Scientists and officials are expanding wastewater monitoring across the U.S. and encouraging community members to collect waste samples from birds. They hope to track this outbreak as they prepare for the next one.
Relating to: CDC warns of more bird flu cases in US after second human infected from cows
A new dashboard was launched last week by the Centers for Disease Control and Prevention (CDC) to track influenza A in wastewater across the country. It does not specifically track H5N1, but the highly pathogenic bird flu variant is part of the influenza A family.
The dashboard helps identify hotspots in the U.S. where influenza A is increasing, and since flu rates among humans are low this time of year, such an increase could alert scientists and the public to potential H5N1 outbreaks.
“I’m really pleased to see them sharing the data they have,” said Marc Johnson, a professor at the University of Missouri School of Medicine and leader of the wastewater surveillance laboratory in Missouri.
Another project turns to citizen scientists, high school students in New York City, to collect samples of bird droppings for infectious diseases.
Volunteers clad in personal protective gear are trained to collect fecal samples from local parks and then work with scientists at the Icahn School of Medicine at Mount Sinai to analyze what pathogens are present.
This is how H5N1 was first discovered in New York City in late 2022, according to a new study.
“There’s a lot of potential for citizen science, particularly for increasing surveillance coverage of pathogens,” said Philip Meade, lead author of this study and a researcher in the Mount Sinai laboratory.
“It is very difficult to fully understand the viruses circulating around us,” he said.
Meade said the citizen science program, called Virus Hunters, could be expanded to other migratory bird flyways along the west coast and midwest.
“The more people we have in the field to help us generate the data and understand what’s going on, the better it is for us and also for the wildlife,” said study co-author and community manager Christine Marizzi. science for BioBus, a mobile research laboratory that works with students.
Citizen science programs don’t just increase the number of people collecting samples, Marizzi said. They also build trust in science among communities.
“We’re doing this with the public. We’re actively involving the community from the very beginning,” he said. “We’re disseminating information so that when the next pandemic hits we can build the trust that you really need. That’s going to be very, very important.”
Part of the challenge of tracking the emergence of viruses from animals is the intensity of the task. Generally, animals (and humans) are only tested when they are sick; but scientists are now learning that H5N1 can circulate asymptomatically in cows and possibly other animals.
Noninvasive sampling like this can track pathogens even when no symptoms are present.
There were gaps in testing during this bird flu outbreak, as farms and workers faced negative consequences if they tested positive. Testing wastewater helps authorities understand what pathogens are circulating without directly testing animals and humans.
“If any of the farms have municipal sewage, we can test it; we don’t need to go to the farms,” Johnson said. “I think this is a really good idea, not just for dairy, but especially for the lower tiers of meat processing plants, so we can check if it spreads to non-dairy animals as well.”
Dairy cow infections are often detected by testing their milk because the udder has been proven to contain high concentrations of influenza virus; but with other non-lactating animals, it can be difficult to know where to test the animal to get accurate results. . “Testing in the lower parts of meat processing plants is a great idea because it doesn’t matter which part of the cow it is in,” Johnson said.
H5N1 was detected in the wastewater of nine of 10 Texas cities examined in a recent prepress study. The authors concluded that most of the virus probably came from animals, but infections in humans cannot be ruled out.
“Whether it’s coming from cattle, people, birds or something else, we get an idea of how much there is, so if there’s a change we know to pay attention,” Johnson said. “We need a baseline of what’s going on so we can see if things are getting worse or getting better.”
If nationwide influenza A monitoring had been done a few months earlier, authorities could have detected an H5N1 outbreak in cows much earlier, he said. Scientists believe the current outbreak started in late 2023, but it was only detected in late March.
Monitoring wastewater can also help detect contamination from farms, especially to new strains.
This cow-adapted flu variant may continue to acquire mutations as it spreads back into bird populations or spreads into new species.
“When viruses spend time in different hosts, they evolve to become better at replicating in those hosts. So when a virus like this gets into a mammalian host and stays there and starts circulating in that host, that’s a very concerning situation for us,” Meade said.
“If this works for the pigs, that’s when we need to start worrying,” Johnson said. Typically pigs are checked for such diseases only when they become ill, but asymptomatic infections may be missed. “If the pigs aren’t getting sick, they could already be inside the pigs and we wouldn’t know.”
Undetected infections among humans will also be a major concern.
“If we missed it on dairy cattle for five months, we may have missed it on something else. “And that could be something much more concerning than dairy cows,” Johnson said.