For months, concerned that the current strain of bird flu is much more likely to infect humans than previous strains, experts have called on U.S. health officials to act more aggressively to reduce human infections and prevent a potential pandemic. Those calls will likely become even more urgent.
Late Sunday, Colorado Department of Public Health and Environment Five employees at a poultry plant in Weld County, Colorado, have reportedly tested positive for avian influenza, four of which have been confirmed by the federal Centers for Disease Control and Prevention (CDC) and one case is pending confirmation.
These cases were caused by a large influenza outbreak on a farm, 1.8 million The workers were killing chickens, a process known as culling.
The Governor of Colorado Disaster emergency The announcement of the positive cases by state health officials in response to the outbreak was a dire event: it was the first time a cluster of human infections had been reported on a single farm in the United States, underscoring the seriousness of the virus.
Time to change
State health officials said the workers had mild symptoms such as conjunctivitis and respiratory illness and none were hospitalized, but the incident marks a turning point that experts have long feared.
“I’m very concerned that this is already on the brink of infecting humans, and that once it does, it’s going to be really difficult to control,” says Seema Lakdawala, a microbiologist and immunologist at Emory University who specializes in influenza. “What’s been driving me over the last few months has been to prevent H5 from becoming a pandemic. I’ve never felt closer to a pandemic than I do now.”
The CDC, in its own way, has echoed those concerns, speaking generally of “pandemic potential” if H5N1 or any other new flu virus were to infect humans, but added that the agency has not yet identified genetic changes in the virus that would make it more likely to infect humans and continues to determine the risk to the general public is low.
Frontline Farmworkers
This fundamental concern, having already demonstrated the ability to adapt to multiple animal species and now infect humans, has led experts and researchers to call for further testing, including blood testing for both farm animals and workers, and for the preparation of vaccines and antivirals. They also want farm workers to be educated on the importance of wearing personal protective equipment, and for the CDC, USDA and other health agencies, especially at the state level, to increase urgency.
Farmworkers are considered on the front line of risk because of their close proximity to both chickens and dairy cows, where the H5N1 virus has already been found in alarming numbers in the US. And testing for both animals and the people who work near them is limited. Experts say the key is to expand testing now, not later. Waiting for more clusters of infections to emerge will only invite mass infection, they say.
“I want them to take swabs not only from the people who have symptoms that they’re talking about, but also from asymptomatic people in the same farm families and in the community,” said immunologist Rick Bright, a former federal health official, “and take blood samples for serological testing.”
Serological tests could help identify people who were infected and had mild or asymptomatic H5N1 symptoms that investigators may have missed. For example, if a family member of an infected worker tests positive, that could indicate person-to-person transmission. “And that’s really important to confirm,” Bright says.
CDC release The announcement on this incident included the news that, at the request of the state of Colorado, they would be sending a team to assist the state in its investigation. The wording was noteworthy: Despite the implications of animal-to-human and possibly human-to-human (there is no evidence of this yet) virus spreading across the country, the CDC should still be asked to participate in each state’s investigation of this issue.
Federal agencies cannot force individual farms to test their animals or workers — that power resides with state, and sometimes county and local, governments, and researchers say past experience has shown that they will be reluctant to undertake a testing process that could lead to farm closures and loss of workers.
But there are other problems that also need to be addressed quickly, including what experts say are crippling delays in reporting test results by the US Department of Agriculture (USDA).
“We’re not seeing any improvement in transparency from the USDA,” Bright said. “Last week they put about 80 viruses into the database, but when you look at those 80 viruses, it’s a collection of viruses that were taken from birds. The samples were taken from 2023 and early 2024. It’s ridiculous…USDA’s lack of transparency and timeliness in their data is forcing us to make a lot of guesswork.”
Bright hopes to look at viral sequences from cows, cats, mice and humans over recent weeks to understand whether the virus is changing in ways that might make it spread more easily or cause more severe disease. “And we need to unmask it so we can identify when and where the blood samples were taken,” the immunologist says.
Even taking into account coordination issues among federal, state, and local agencies, there is a clear shortage of human testing in the United States. According to the CDC: Over 60 people Tests for the new avian influenza virus have been conducted on farms since infections began this spring, and often involve swabs of the eyes, nose and throat to check for active infection, but do not involve drawing blood for serological tests.
“There are barriers for public health officials to achieve this, but there is certainly value in doing more widespread testing,” said Anise Lowen, a virologist and influenza expert at Emory University, who counts potentially infected farm, dairy and poultry workers among those who need testing.
“We don’t really know how widespread it is,” the virologist said. “The few documented cases could be the tip of the iceberg, but we don’t know because there aren’t enough tests.”
Bright is among those calling for the CDC to immediately provide vaccines to farmworkers and others at high risk of catching avian flu, arguing that anything less would be unethical. There is a shortage of supplies There is more than enough available to effectively vaccinate the entire population in the event of a major outbreak, starting with those on the front lines.
“When you’re dealing with a deadly virus, you can’t have a little bit of conjunctivitis or a little bit of respiratory issues,” Bright said, adding that the virus has already demonstrated the ability to mutate “very easily and very rapidly” and “can cause severe illness and death. So let’s stop that progression instead of just waiting and letting it get worse.”
Whether the CDC will follow the experts’ suggestions remains an open question. So far, the agency’s response has been muted: no change Officially recommended.
But for those who have been tracking this avian flu closely, the signs are ominous and call for a proactive response: vaccinating frontline farm workers. “That’s why we have the stockpile,” Seema Lakdawala says. “I’m surprised it hasn’t been utilised… We always expected this to happen at some point.”
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