We close the week with an explainer — what you need to know about the two separate strains of bird flu in the headlines, who is at risk of infection, how it can be spread, and what the common symptoms are. The short version: No, this is not Covid 2.0.
How worried should you be about bird flu?
Not that worried; right now, there’s no good reason to say, “Here comes Covid 2.0.” (Look, I get why you would wonder if someone at the Democratic National Committee would want some excuse to keep Joe Biden doing Skype calls in the basement for the remainder of the year. But so far, this isn’t it.)
Here’s the first thing you should know: There are many kinds of viruses that get labeled “bird flu” in headlines. To the extent laymen are freaking out, it is likely because they’re conflating reports about two different strains.
The form of bird flu currently going around American farms is H5N1. It is widespread in wild birds, sporadically breaks out in poultry flocks and mammals, and there is an ongoing multi-state outbreak in dairy cows. There are currently three human cases in the U.S., the known level of person-to-person spread is none, and the current public-health risk from this strain is low, according to the U.S. Centers for Disease Control and Prevention. There has been a grand total of four infections in human beings in the U.S. since 2022.
“No human bird flu infections have been reported from proper handling of poultry meat or from eating properly cooked poultry or poultry products.” So, despite White House press secretary Karine Jean Pierre’s assertion that she’s protected from bird flu because she’s vegan, you are not at risk of catching bird flu at the dinner table, as long as you’re not eating raw chicken meat.
If you work with poultry, you are at higher risk of being infected with H5N1 than the average person; if you know someone who works with poultry, you are unlikely to catch the virus from that person. As the CDC summarizes:
Nearly all human cases reported globally since 2022 were associated with poultry exposures, and no cases of human-to-human transmission of HPAI A(H5N1) virus have been identified.To date, HPAI A(H5N1) viruses currently circulating most commonly in birds and poultry, with spillover to mammals and humans, do not have the ability to efficiently bind to receptors that predominate in the human upper respiratory tract. This is a major reason why the current risk to the public from HPAI A(H5N1) viruses remains low. However, because of the potential for influenza viruses to rapidly evolve and the wide global prevalence of HPAI A(H5N1) viruses in wild birds and poultry outbreaks and following the identification and spread among dairy cattle in the United States, additional sporadic human infections are anticipated.
In the three cases reported in the U.S. this year, two patients reported conjunctivitis (“pinkeye”), and one reported upper-respiratory symptoms. In all three cases, the patient was treated with Oseltamivir (an antiviral), and no additional cases were detected. As far as public health problems go, H5N1 appears fairly manageable, with minimal consequences for human beings, at least here in the United States.
The CDC recommends that to minimize chance of infection, “people should also avoid unprotected exposures to animal poop, bedding (litter), unpasteurized (“raw”) milk, or materials that have been touched by, or close to, birds or other animals with suspected or confirmed A(H5N1) virus.” (Raise your hand if you’re a little surprised that the word “poop” appears in official document of the U.S. government.)
Pasteurization eliminates active bacteria and viruses in milk; this is why the U.S. Food and Drug Administration is urging states to take steps to minimize the risk of anyone catching the virus from consuming raw milk:
For states that permit the sale of raw milk within their state, use regulatory authorities or implement other measures, as appropriate, to stop the sale of raw milk that may present a risk to consumers. This may include restricting the introduction of raw milk that may contain viable HPAI H5N1, for human or animal consumption, within a defined geographic area or within your state. If HPAI H5N1 virus is identified within a herd, there is a risk that viable HPAI H5N1 virus could be present in raw milk from the herd, even when clinically ill cows are segregated.
The form of bird flu that reportedly killed a man in Mexico recently is H5N2. (Yes, it might be preferable if we came up with more distinct terms if we’re going to be talking about these viruses a lot.)
The man who succumbed to the virus in Mexico is atypical. From NBC News:
The patient in Mexico had been bedridden for several weeks prior to developing symptoms.According to the World Health Organization, on April 17, the man developed fever, nausea, diarrhea, shortness of breath and general malaise. A week later, on April 24, he was hospitalized and died that day.Sutton said that it’s important to note that the man had multiple underlying medication conditions, which likely exacerbated his infection.“The person may have already been quite sick,” Sutton said. “That changes the calculation a little bit more than, say, a healthy farm worker getting infected.”The WHO said no other cases were reported during its investigation. Of the 17 contacts identified and monitored at the hospital where the patient died, one reported a runny nose.However, experts still don’t know how the man became infected with the virus, as he wasn’t exposed to poultry or to other animals. If he was infected by another human, that suggests that there could be additional unidentified cases.“It is concerning that a new virus subtype has infected a human,” Sutton said.Dr. Michael Osterholm, an infectious disease expert at the University of Minnesota, said human-to-human transmission is unlikely. “They likely picked it up from the same place.”Data shows that the H5N2 virus that infected the man is a low pathogenic virus, meaning it is unlikely to cause severe illness, said Osterholm.
The H5N2 strain is nothing new; there was a significant outbreak among chickens in Texas in 2004 and 2005, with no infections of humans reported. My guess is that unless you work in the poultry industry or in that particular part of Texas, you never heard about it. Significant avian-flu outbreaks, with and without human infections, occur every couple of years. They are generally isolated to particular parts of the country and pass without serious incidents — unless you’re a chicken.
When you hear news about a virus spreading through some animal, it usually means it’s something to keep an eye on, but not a sign that we’re headed for another life-altering global pandemic. I’m going to quote the U.S. National Institutes of Health: “nearly all viruses and bacteria that infect other organisms are completely harmless to people.”
(Covid, or SARS-CoV-2, really stands out as a bat coronavirus that somehow developed the ability to spread like wildfire among human beings and kill them if the infection were virulent enough or their immune systems were weak enough. Why, it’s almost like it gained a function somewhere along the way! Oh, and we never found the precise strain of SARS-CoV-2 in a bat or food animal. But hey, that’s totally normal! Nothing suspicious there!)
Yes, it sounds ominous when you hear, “The CDC is monitoring cases of bird flu across the U.S.” But the CDC monitors a lot of things; that’s their job. The CDC is also monitoring salmonella in cucumbers. If you want to avoid cucumbers, be my guest.
There is an argument that the outbreaks of bird flu on U.S. dairy and poultry farms could be worse than we know because of insufficient monitoring. Public health researchers at Johns Hopkins University, Erin M. Sorrell, Monica Schoch-Spana, and Meghan F. Davis, writing in the New York Times in early May:
When it comes to H5N1, the dairy work force — which includes on-farm workers and milkers, people working in the milk processing plants and in slaughterhouses, truck drivers and other professionals who come onto farms — is among those with the highest exposure.The majority of hired farmworkers in the United States are from Mexico and Central American countries; many lack authorization to work here legally. Undocumented workers may be worried about public health reporting systems putting them at risk for immigration enforcement or preventing future chances of gaining a visa or permanent residency status.Communication is a further concern. According to a 2019 survey, over half of U.S. dairies have employees whose native language is not English; these individuals most often speak Spanish, but some speak only Indigenous languages such as K’iche’ or Nahuatl. Many workers have limited literacy and education that dairy farms accommodate with pictorial signage and visual training materials. Any effective bird flu education campaign would have to be similarly tailored to these workers’ communication needs — a capacity that not many health departments have.
This is not a crazy concern, and some, like MBD, have argued that this is one more reason why high levels of illegal immigration, and widespread employment of illegal immigrants, are part of a fundamentally exploitative and immoral system. I have no real disagreement with this, but let’s just point out that if waved a magic wand and replaced every illegal worker on every poultry and dairy farm with a citizen or legal immigrant or guest worker, we would have the same risk of human infection. In this context, illegal immigrant labor represents monitoring and communication problems, not a greater-risk-of-infection problem.
Also, note that some H5N1 infections can be asymptomatic, and some infections can have minor symptoms, easily mistaken for a common cold. Plenty of people develop pinkeye and treat it with over-the-counter medication like eye drops and never bother to visit the doctor. It’s particularly difficult to identify and treat asymptomatic infections because they’re . . . well, asymptomatic. People don’t know they’re infected.
You know why I feel pretty good about our ability to monitor bird flu? We’re not relying on any information from the Chinese government! (Check out this assessment I wrote on January 20, 2020, about two months before the world shut down. “Probably the single most frightening aspect is the possibility that either the Chinese government is still guessing at how far the virus has spread, or that they’re not being honest about the risk.”)
Yet somehow, there are some scientists who argue the problem is that the U.S. government isn’t enough like the Chinese government. Helen Branswell, writing at STAT News:
It’s not lost on many scientists, here and abroad, that the paucity of data coming out of the U.S. is not dissimilar to the limited information flow out of China in the early days of the Covid-19 pandemic — a situation the U.S and other governments complained about loudly at the time. With the shoe on the other foot, however, there is no overt effort to make farmers cooperate.“A lot of criticism was leveled at China for their early response to Covid-19 — some of it reasonable, a lot of it extremely ignorant. Are we currently making some of those mistakes ourselves?” wondered Kristian Andersen, an evolutionary biologist and a professor of immunology and microbiology at Scripps Research Institute in La Jolla, Calif.
No! We are going to make all new, different mistakes. Lord knows the U.S. government has more than its share of flaws. But our government doesn’t arrest or “disappear” doctors who make public statements that are contrary to the government’s line, it doesn’t order doctors to destroy samples, and while lots of people like to complain that America has “state-run media,” there is no shortage of venues that report information independent of any U.S. government influence or control. Also note that in the modern People’s Republic of China, the greatest or more-consequential sin is offering information that makes the leader look bad. In the United States of America, the greatest or more-consequential sin is getting it wrong.
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