An unusual increase in the number of flu viruses detected at wastewater treatment plants in California and other parts of the country has some experts concerned that H5N1 bird flu could spread further and faster than initially thought health officials.
In recent weeks, wastewater monitoring at 59 of 190 municipal and regional wastewater treatment plants in the United States has revealed an off-season increase in influenza A viruses – a category that also includes H5N1.
The tests – which aim to monitor the prevalence of “normal” flu viruses that affect humans – also showed a moderate to high upward trend at 40 sites across California, including San Francisco, Oakland and San Diego. Nearly every city tested in the Bay Area has a moderate to high increase in Type A viruses.
Alexandria Boehm, professor of civil and environmental engineering at Stanford University and principal investigator and program director for WastewaterSCAN – an infectious disease surveillance network run by researchers at Stanford Laboratories, Emory University and the Alphabet Inc.’s life sciences research organization – was careful to note that an increase in human influenza A virus in wastewater does not necessarily mean avian influenza is present. However, this raises this question.
Some experts worry that H5N1 is going essentially unnoticed, spreading undetected among birds, livestock and possibly humans, and say the increase in positive test results at sewage plants could be an indication. They fear that if the virus continues to spread among livestock, there is a higher risk that the virus will mutate in a way that makes it even more threatening to humans.
“There appears to be an outbreak throughout California and, as far as I know, they have not yet reported any infected cows in the state,” said Marc Johnson, a professor of molecular microbiology and immunology at the University. of Missouri, referring to the group of yellow and orange dots on the WastewaterSCAN map.
Johnson is among a number of experts urging the U.S. Centers for Disease Control and Prevention to test specifically for H5N1 and make those results public.
Avian flu has been positively identified in 42 cattle herds across nine states, suggesting its spread has been somewhat limited. However, wastewater surveillance tests show an increase in flu viruses in 23 states, some of which have seen outbreaks on dairy farms.
Boehm said they are testing in 41 states; Not all states participate in the WastewaterSCAN academic program.
So far, no herds have been infected in California, which is the nation’s largest milk producer. The state supplies about 20 percent of the nation’s milk, is home to about 1,300 dairy farms, and has about 1.7 million dairy cows.
Most human flu viruses are seasonal, arriving in the fall and disappearing in early spring. Therefore, finding the virus in wastewater during these times is “what we would expect when there are more flu cases in hospitals, more hospitalizations, more emergency room visits,” Boehm said , professor at Stanford.
“What we noticed this year is that after the flu season, a fraction of the wastewater treatment plants that we studied, and when we looked at them closely in late April, saw increases” , she said, including some of them. “obvious” cases like two in Amarillo, Texas, where they knew the H5N1 virus had been detected in dairy cattle nearby.
The team contacted the local public health department and obtained permission to test for the avian flu virus. It was a match. The same was true for wastewater from a Dallas factory.
Boehm said the results suggest that the increases seen at these other sites – 59 of the 190 they track – could also be due to bird flu.
She said the sites they look at deal with municipal, non-agricultural wastewater, “so they don’t receive agricultural runoff.” »
Instead, at least in Amarillo’s case, these are likely licensed dairy processing centers — places that made cheese or yogurt…that had a permit to discharge into the waste stream “.
The cause of the increasing trend at other sites is unclear. But if this increase is the result of avian flu-infected dairy products entering the municipal waste stream – and since milk is typically trucked from dairies to processing centers – the source of the infection is It’s probably not too far away. These positive sites provide a geographic indicator that public health officials can examine more closely. (The CDC has said that pasteurizing milk kills the virus.)
Johnson, who developed an H5N1 test to test Missouri wastewater, was asked by federal authorities not to use the test for fear it could “add to the confusion.”
“This is the perfect example of why it makes sense” to specifically test for H5N1 in wastewater, he said. “Because then you’ll know if it’s really H5, because no matter where it comes from, if it shows up in California, that means something.”
Johnson said if tests show it is H5N1, there could be infected cows in California.
The CDC monitors about 600 sites, and “what we’re seeing are very localized increases that are out of season for seasonal flu,” said Amy Kirby, senior policy fellow at the waterborne disease prevention branch. from the CDC.
She said when they see these increases, they take a closer look at the situation.
In an interview Friday, she said she was unable to provide more information because the agency was “finalizing that data and verifying it to make sure it’s correct.” .
Tom Skinner, a CDC spokesman, said the data will be available Tuesday on the agency’s bird flu dashboard. He said in an email that some of the sites viewed were in California, but declined to add more information until the agency released its own dashboard.
For some researchers, the increase in the number of viruses detected in wastewater is a call to action.
“I think we have a good opportunity here to prepare for the worst-case scenario,” said John Dennehy, a virologist at the Graduate Center of the City University of New York. “Now we know it’s there. We know it hasn’t been transmitted to humans yet, but can we mobilize the public health infrastructure to prepare in advance if this infection were to jump from cows to humans? Does it come from milk? Or another way?
It was in Dennehy’s lab that the New York City coronavirus wastewater test was developed.
Dennehy and his colleague Denis Nash – distinguished professor of epidemiology and executive director of the Institute for Implementation Science in Population Health at the City University of New York – said that only since around 2020 have researchers use wastewater monitoring to monitor public health.
It is now considered a “front-line” surveillance method of collecting information on outbreaks of influenza, polio, rhinovirus and other diseases. But this initiative is largely driven by academics and local agencies.
In the case of avian flu, a more centralized or organized surveillance and messaging system is needed, they said.
“I think the important thing here is that the CDC should describe what’s happening with influenza A in wastewater,” Nash said. “It’s great that academics are doing it. We all step up because it often seems like the government is a little late or just not engaged. But in reality, the CDC should be leading this project. »
Calls to wastewater treatment centers in Santa Cruz and Oakland went unanswered. A question to a manager at the UC Davis Wastewater Treatment Center, which shows an uptick, also went unanswered.
News Source : www.latimes.com
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