Avian influenza infection among farm workers is a problem for everyone

It was inevitable that it would happen again: For the second time in two months, the United States has confirmed a case of bird flu in a dairy farmer who works on a farm with cows infected with H5N1. “The only thing that's surprising is how long it's taken for these new cases to become known,” said Steve Valeika, a veterinarian and epidemiologist in North Carolina.

The actual number of people infected is almost certainly higher. several weeks, Anecdote Reports of sick farm worker The H5N1 virus has been detected little by little from all over the country. Dozens of herds in nine statesAccording to the federal government's tally, 1,000 people have been infected. Testing of people and animals is limited, and cooperation from farms is still insufficient. Due to the gap between reality and what governments can measure, the world is unable to grasp the full extent of the spread of infection. It could also reduce the ability of experts to detect human-to-human transmission if it someday occurs. “I wouldn't be surprised if there were dozens of cases at this point,” Vareika said.

With federal guidelines still in place, the risk to the majority of the population remains low. EmphasizeBut that confidence is fading with “the threat to agricultural workers remaining elevated,” said Jennifer Nuzzo, director of the Pandemic Center at Brown University's School of Public Health. Infectious diseases too often hit the most vulnerable in society the hardest. Now, the future of this virus depends on America's ability to protect communities where health and safety are routinely disregarded.

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Like this: first case There is at least one reassuring element to this second report compared to reports of dairy farm workers contracting avian influenza. In both cases, the cause appeared to be frequent contact with infected dairy cows, resulting in mild illness. Eye symptoms only. (in Another US casefrom 2022, a man contracted the virus from poultry. Malaise This is the only symptom reported.) Cow's udder and human eye Both primarily contain receptors for H5N1 similar to those found in birds, and although experts suspect these receptors may be easy entry points for the virus, the virus remains an avian pathogen. It is thought that. The virus will likely need to make another evolutionary leap before it can fully spread among people. Seema Lakdawala, a virologist at Emory University, said most people are “not worried about H5 right now.”

But dairy workers have reason to be worried, Lakdawala added. parlor In dairy cow milking parlors, cows are tied to the milking machine by clinging to their udders, turning the machine until the milking speed slows down, and then letting go of it, which shakes it off “at the cow's eye level” and releases the foamy liquid. Lakdawala told me that passersby were sprayed with water. It is not necessary to disinfect each animal.—And cleaning To do The work often involves flushing with high-pressure hoses, which also atomize the milk. As workers attach the machines to each cow and manually regulate the initial flow of milk, they often have direct contact with the udders. Even if workers don't get milk on their hands (though they will eventually touch their faces), they're constantly exposed to aerosols, droplets, and sprays, Lakdawala says.

If you have infected cows, it means: many Exposure to the virus. Lakdawala's lab has been studying how long H5N1 can survive on milky surfaces. Initial ResultsThe findings, which have not yet been published in scientific journals, suggest the virus can persist for at least one to three hours on the same types of plastic and metal commonly used in milking equipment. This creates a clear pathway for the virus to move between animals, and also creates a very easy route for humans to infect humans, Lakdawala said. Improper disposal of milk Milk from cows on infected farms can pose an infection risk, especially if the cow is a dairy cow and must be milked. (Several farm cat (The virus appears to have been contracted by drinking raw milk.) The USDA recommends that all milk be heat-treated before being discarded, but some farms, especially smaller ones, may not always have access to the necessary equipment or manpower, Lakdawala said.

The CDC: urged farm workers Wearing goggles, gloves, high-quality respirators, and other protective equipment is recommended in these environments. But these recommendations are not enforceable in practice, and it is unclear how many farms or how many workers on those farms are following them. As the weather heats up in the spring and summer, wearing such gear may become even more uncomfortable, Lakdawala said. This is especially true in the steamy, cramped environments where the most exposed people do the most work. Goggles and other tight-fitting eye protection are especially tricky. “It gets dirty quickly,” Lakdawala said. Workers cannot see what they are doing through milk-splattered lenses.

Passion for cow and human trials was also low On farms, managers and employees carefully consider the financial and personal risks they face if one of their cows is reported to be sick. And asymptomatic cows Probably responsible to a considerable degree Spread the wordThe USDA only requires the following inspections: part of cow Moving between states. This basically “makes it impossible for farmworkers to detect the virus before they are infected,” Nuzzo said. Similarly, CDC The UK government has said that “testing asymptomatic people” for H5N1 is “not routinely recommended” and says there is no guarantee that people who have been in close contact with an infected person will be able to get tested for the virus. Such delays could allow infections to smolder, past the point at which intervention with drugs such as Tamiflu or prevention of infection to close contacts is possible. The fact that this second case has been found does not mean that testing is sufficient. MichiganNuzzo said dairy farmers are being more proactive in testing their herds. He and Lakdawala say stockpiles of vaccines should be made available in bulk to farm workers while the risk is still high, but federal government employee No injections offered yet(The USDA and CDC did not respond to requests for comment.)

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These shortages should be worrying for all Americans battling a low-profile infectious disease. But Ann Sosin, a public health researcher at Dartmouth College, said H5N1 could exacerbate existing health disparities, especially among farmworkers—a group that includes many immigrants and the uninsured who live in rural areas. If protecting farmworkers is a priority, “I think we're failing in some ways,” Valeika said.

Researchers also aren't sure how much risk an infected farmworker poses to close contacts. Other types of conjunctivitis are quite contagious, and Lakdawala says it's possible for someone who has just rubbed their eyes to transmit the H5N1 virus by touching someone else's hands and then touching their face. Experts are also concerned that eye infections could spread to other parts of the body, including the respiratory system, especially if the virus mutates in a way that allows it to adapt to receptors in the lungs. (Fortunately, a nasal swab from a Michigan dairy worker was found.) H5 virus negative.

The virus does not appear to have reached such a spike yet. However, influenza infection remains a problem for everyone. “If we can't stop transmission in the most at-risk groups, the threat to the general public will only increase,” Sosin told me. H5N1 may not be transmitted from person to person. However, even if the virus had become infected, the spread would have been facilitated by community transmission among people that American society was unable to adequately protect.