Public Health

Bird flu in milk: Raw milk vs pasteurized milk, H5N1 symptoms and new STI statistics 2024

. 10 MIN READ

AMA Update covers a range of health care topics affecting the lives of physicians, residents, medical students and patients. From private practice and health system leaders to scientists and public health officials, hear from the experts in medicine on COVID-19, medical education, advocacy issues, burnout, vaccines and more.

How does bird flu spread to humans? Is raw milk safe to drink? What are the symptoms of bird flu in humans? Are STI rates increasing? Why are STIs on the rise?

Our guest is AMA Vice President of Science, Medicine and Public Health Andrea Garcia, JD, MPH, AMA Chief Experience Officer Todd Unger hosts.

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  • Andrea Garcia, JD, MPH, vice president, science, medicine & public health, American Medical Association

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Unger: Hello and welcome to the AMA Update video and podcast. Today, we have our weekly look at the headlines with the AMA's Vice President of Science, Medicine and Public Health, Andrea Garcia. I'm Todd Unger, AMA's chief experience officer. Andrea, welcome back.

Garcia: Thanks, Todd. Appreciate the opportunity to be here.

Unger: Well, we're going to start off with a topic we've covered in the past several weeks, and that's bird flu. This past week, we learned about another human case of bird flu. Andrea, tell us more about it and what it could mean?

Garcia: Yeah, it was last Wednesday when the CDC reported that a second person, Michigan dairy worker, had tested positive for H5N1 bird flu. The individual works on a dairy farm where each 5N1 virus has been identified in cows. Although, federal officials have said the case does not change their assessment, that the risk to the public does remain low.

This has prompted an increased urgency for testing and treatments. Given this, we've seen the government introduce additional financial incentives for dairy producers to expand testing of their cattle and accelerate that timetable to ready nearly five million doses of vaccine in the case that the virus does become more widespread among people.

Unger: Well, first off, Andrea, was the worker seriously ill?

Garcia: Thankfully, no. That Michigan worker, like the one in Texas, experienced mild eye symptoms and has since recovered, according to state officials. A nasal swab of the worker had tested negative for influenza in Michigan, but an eye swab was then shipped to the CDC in Atlanta, where it tested positive for avian flu.

The CDC said that this case doesn't come as a surprise since they have ramped up surveillance. The agency spokesperson also praised Michigan for its efforts and swift response. Michigan has enrolled 170 farm workers into its active monitoring program, where they're receiving daily texts from the health department, asking these individuals if they're having symptoms.

This particular worker indicated that they were having symptoms, and the Michigan health officials responded really quickly with testing and reporting. And as of May 22, more than 350 people with exposure to dairy cows or infected unpasteurized cows milk are being monitored.

Unger: So what can we take away from all of this?

Garcia: Well, one thing CDC officials have found reassuring is that the nasal swab tested negative because it reduces, not eliminates, but reduces that likelihood of a respiratory route of transmission. Respiratory spread would make this virus much more contagious. CDC officials have also said that the case really underscores the importance of personal protective equipment being used by workers at dairy farms and slaughter facilities.

Federal and state officials have made PPE supplies available to dairy farms, but have not required its use.

Unger: Now, Andrea, earlier you mentioned five million doses for production. Is it time for those who are at high risk to get vaccinated?

Garcia: Well, the federal government said it's not planning for vaccination of workers and others who come into close contact with dairy cattle at this time. Factors that could prompt a vaccination campaign include transmission from animal to human, evidence of human-to-human transmission, or a case of H5N1 without any link to a dairy farm. As we talked about last week, CDC is also planning to continue flu monitoring through the summer.

That's something that we wouldn't ordinarily see them do. And physicians are being encouraged to consider bird flu when evaluating patients who have conjunctivitis or respiratory illness following an exposure to agriculture or livestock.

Unger: Now, Andrea, given the situation that we're seeing on the farms and with workers, is our commercial milk supply still considered safe?

Garcia: Yes, so most commercial milk in the United States is pasteurized. Pasteurization kills germs by heating milk to high temperatures. While FDA has found traces of the virus in 20% of dairy products sampled from grocery shelves nationwide, officials have not found signs of live infectious virus in those samples and have therefore said that pasteurized milk is safe to consume.

The New York Times recently noted, though, that this study could have global implications. If this outbreak becomes more widespread, not all countries do have central pasteurization.

Unger: And that's important, as we're going to find out from the next set of questions, because we're going to talk about the dangers of drinking raw milk, especially right now. A new study confirms that those fears are founded. Andrea, tell us more about that?

Garcia: Yeah, this was big news heading into the holiday weekend. There was a study published on Friday in the New England Journal of Medicine, and it found that mice rapidly became sick after being fed unpasteurized milk contaminated with H5N1. A New York Times article reported on that study that this is not altogether surprising.

At least half a dozen cats have died after consuming raw milk containing the virus. But the new data adds to the evidence that raw milk containing the virus may be unsafe for other mammals, including humans. And as we talked about last week, the FDA has said that consuming raw milk is unsafe. It's been unsafe for a long time now, well before this outbreak.

Unger: Absolutely. And yet, there's a lot of misinformation out there circulating about raw milk. Can you take us through some of the misconceptions and what physicians need to be telling their patients?

Garcia: Well, one misconception is that refrigeration kills the virus in raw milk. That study published on Friday showed otherwise. The virus actually declines slowly in cool temperatures. So the virus may remain infectious for several weeks in raw milk with refrigeration. Some have also said that raw milk just tastes better, it's more nutritious and it boosts immunity.

But actually, pasteurization does not have a significant impact on the nutritional value of milk. In most pasteurized cow milk is also fortified with vitamin D, which helps absorb calcium. According to the CDC, consuming raw milk can lead to serious complications or even death from a variety of pathogens, especially in people with weakened immune system.

If we look at the data from 1998 to 2018, outbreaks traced to raw milk consumption led to 228 hospitalizations, three deaths and illnesses in more than 2,600 people.

Unger: I think the message is pretty clear, avoid raw milk. Andrea, we'll continue to track this outbreak. But for now, let's turn to another global health issue. Last Tuesday, the World Health Organization published a report about a major concern for health officials.

Andrea, tell us more about the concern and what we need to know?

Garcia: Yeah, this particular WHO report was referring to STIs or sexually transmitted infections and found that for curable STIs—chlamydia, gonorrhea, syphilis and trichomoniasis—are responsible for more than a million infections daily among people aged 15 to 49. Cases of syphilis in particular have been rising rapidly. According to the report, the number of new syphilis cases among people between the ages of 15 and 49 increased from 7.1 million in 2020 to 8 million in 2022.

Now, that's a pretty sharp increase in a relatively short period of time. Even more concerning is that there have been increases in the rate of congenital syphilis which occurs when people pass syphilis to their babies during pregnancy. Between 2020 and 2022, the rate per 100,000 live births per year rose from 425 to 523. That WHO report also noted that cases of antibiotic resistant gonorrhea are increasing, which was labeled as another concern.

As of 2023, there were nine countries that reported elevated levels from 5% to 40% of resistance to ceftriaxone, which is considered the last line treatment for gonorrhea.

Unger: Wow, so that is an issue on a global scale. Andrea, are we seeing the same kind of trends here in the U.S.?

Garcia: The most alarming concerns here in the U.S. center around the syphilis and congenital syphilis epidemics. CDC data show that the total number of syphilis cases increased more than 17% to 207, 255 cases between 2021 and 2022. And those numbers show that it's reaching the greatest number since we've seen since 1950. Congenital syphilis cases have more than tripled in recent years, with more than 3,700 cases reported in 2022 alone.

Unger: That's a pretty shocking set of numbers. Do we have any idea what's driving this?

Garcia: Well, lack of screening and lack of access to care are two likely culprits. Disruption caused by the COVID pandemic didn't help and likely delayed screening for many. I think in good news, the WHO noted that there have been gains in expanding services for STIs, HIV and hepatitis, and several countries have even eliminated mother to child transmission of HIV and syphilis.

To drive those rates down, that WHO report does outline some recommendations, including efforts to accelerate decriminalization and destigmatize those affected by STIs and other infections, as well as strengthening primary prevention, diagnosis and treatment to raise awareness. The AMA has also developed resources to help physicians improve routine screening for these infectious diseases. That includes a tool kit that covers routine screening for STIs. And we'll link to that resource in the description of this episode.

Unger: Excellent. That's all good to know and something physicians can certainly play a huge role in. Andrea, thanks so much for being here today. That's it for today's episode. If you found this discussion valuable, you can support more programming like it by becoming an AMA member at ama-assn.org/join.

We'll be back soon with another AMA Update. In the meantime, you can find all our videos and podcasts at ama-assn.org/podcasts. Thanks for joining us today. Please take care.


Disclaimer: The viewpoints expressed in this video are those of the participants and/or do not necessarily reflect the views and policies of the AMA.

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