by Amid widespread gaps in US testing for H5N1, a type of bird flu, and as the second case in humans detected, scientists are turning to more creative ways to monitor the outbreak — particularly in human and animal feces .
Scientists and officials are expanding wastewater monitoring across the US and engaging members of the public to collect waste samples from birds. They hope to keep a close eye on this outbreak as they prepare for the next pandemic.
Related: CDC warns of more cases of US bird flu after second person infected by cow
The Centers for Disease Control and Prevention (CDC) launched a new panel to monitor influenza A in wastewater across the country last week. It does not specifically track H5N1, but the highly pathogenic bird flu variant is part of the influenza A family.
This panel helps identify hot spots in the U.S. where influenza A is on the rise – and, since flu rates among people are low this time of year, such a surge can alert scientists and the public to inform about possible outbreaks of H5N1.
“I’m very happy to see that they’re sharing the data they have,” said Marc Johnson, a professor at the University of Missouri School of Medicine and the head of Missouri’s wastewater surveillance laboratory.
Another project involves citizen scientists—high school students in New York City—sampling bird droppings for infectious diseases.
Volunteers, dressed in personal protective equipment, are trained to take fecal samples from local parks, and then work with scientists at the Icahn School of Medicine at Mount Sinai to analyze the pathogens 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, especially increasing the scope of surveillance” of pathogens, said Philip Meade, lead author of that study and a researcher at the Mount Sinai laboratory.
“It is very difficult to have a complete understanding of the viruses that are circulating in our environment,” he said.
The citizen science program, called Virus Hunters, could be expanded to other migratory bird flights along the west coast and midwest, Meade said.
“The more people you have on the ground helping us generate the data now and understand what’s happening, the better this is for us and also for the wildlife,” said Christine Marizzi, study co-author and community director . science for BioBus, the mobile research laboratory that works with students.
Citizen science programs don’t just increase the number of people who collect samples, Marizzi said. They also promote trust in science among communities.
“We do this in collaboration with the community. We have been actively involved with the community since the beginning,” she said. “Getting information so we can build confidence that you really need once the next pandemic hits. That will be very important.”
Part of the challenge of monitoring the emergence of viruses from animals is the breadth of the task. Normally, animals (and people) are only tested when they are sick – but scientists are now learning that H5N1 can circulate asymptomatically in cows and possibly other animals.
Non-invasive sampling like this can monitor pathogens even when there are no symptoms.
There have been gaps in testing during this bird flu outbreak, as there are negative consequences for farms and workers if they test positive. Wastewater testing helps officials understand what pathogens are circulating without directly testing animals and humans.
“If any of the farms are on city sewage, we can test it — we don’t have to go to the farms,” Johnson said. “I think this is a very good idea, not only for dairy but especially downstream from meat processing plants, so we can watch whether it has spread” into non-dairy animals.
Infections in dairy cows are usually detected by testing their milk, as udders have been shown to contain high concentrations of the influenza virus – but in other non-lactating animals, it may be difficult to know where to test the animal to get accurate results. . “Testing downstream from meat processing plants is a great idea because it doesn’t matter what part of the cow it’s in,” Johnson said.
H5N1 was detected in the wastewater of nine out of 10 Texas cities surveyed in a recent preprint study. Most of the virus is likely to come from animals, but human infections cannot be ruled out, the authors said.
“Whether it’s coming from cattle or people or birds or whatever, let’s think about what’s there, 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 better.”
If nationwide influenza A monitoring had been in place a few months ago, he said, officials might have detected the H5N1 outbreak in cows much earlier. Scientists believe the current outbreak began in late 2023, but was only discovered at the end of March.
Wastewater monitoring may also help detect on-farm transmission, particularly to new species.
This cow-adapted flu variant may continue to mutate as it splits back into bird populations or diverges into new species.
“When viruses spend time in different hosts, they become better at replicating in those hosts. So anytime a virus like this gets into a mammalian host and stays there and spreads in that host, it’s something that’s very concerning to us,” Meade said.
“If this goes into pigs, that’s when we need to start getting nervous,” Johnson said. Usually, pigs are only checked for illnesses like this when they become ill, but asymptomatic infections may go unnoticed. “If the pigs aren’t getting sick, they could already be in the pigs and we wouldn’t know it.”
Undetected infections among people were also a major concern.
“If we lost it in dairy cattle for five months, we could lose it in something else. And it could be a lot more of a concern than a dairy cow,” Johnson said.
