Public Health

Heat wave 2024: Heat stroke vs heat exhaustion symptoms, plus Mpox and bird flu in milk study


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.

Heat wave safety tips: How long will the heat wave last? What are the first signs of heat exhaustion? Can women get monkeypox? Is there bird flu in milk?

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


  • 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. Welcome back, Andrea.

Garcia: Thanks, Todd. Really appreciate the opportunity to be here.

Unger: Well, it's only been a few days since we last talked, but there is no shortage of headlines today. Number one, heat wave. Andrea, what do we need to know?

Garcia: Well, Todd, there were some CNN headlines this week. And according to those, there is a heat wave not seen in decades that is going to send temperatures soaring for more than half of the U.S. population. And as we can tell from being outside today, that's certainly turning out to be true. As of Monday, there were more than 70 million people who were already under extreme health alerts across the country.

This particular heat wave is being fueled by an intense heat dome, which is a strong zone of high pressure. It started over Northern Mexico and Southwest United States, and it's since shifted eastward and north, and basically is strengthening and expanding in all directions. And while the heat dome may relax or move around, most states are going to continue to see much warmer than normal weather, at least through the end of this month. It is expected that hundreds of records will be tied or broken, and the heat is expected to reach dangerous levels in many places.

Unger: Well, it's not just the temperature records that are the problem here. We know that some people are going to be at higher risk than they realize. Andrea, tell us about that impact between the heat and physical effects.

Garcia: Yeah, well, with extreme heat, the most vulnerable groups are typically outdoor workers, people experiencing homelessness, older adults and then anyone without access to air conditioning. However, there are others who may not realize that they are more susceptible to heat-related illness because of certain common medications that they're taking. I think the New York Times did a really good job of outlining many of these in an article over the weekend. It's something that physicians can make sure that their affected patients know.

Unger: That's interesting. Tell us a few examples of these kind of common interactions.

Garcia: Well, diuretics for one. Doctors often prescribe these to manage heart failure, kidney disease or high blood pressure. They help your body reduce fluid through frequent urination. However, they can also cause dehydration. Ace inhibitors, which are also prescribed to treat high blood pressure, can increase the risk of fainting and falling. They can also suppress that feeling of thirst, which makes it harder to tell when you need to drink more water.

Beta blockers, too, can increase your risk of fainting and falling and making it harder to sweat, which makes it more difficult for your body to keep cool. Some others on the list include calcium channel blockers, certain antipsychotic medications, some antidepressants and thyroid hormone replacement medications. Stimulants such as amphetamines and other drugs used to treat attention deficit hyperactivity disorder may also increase their risk of heat-related illness and then even some over-the-counter drugs, such as antihistamines like Benadryl. I think the bottom line is, if you are on any of these medications, check with your physician so they can talk to you about the appropriate precautions to take over the next few weeks.

Unger: Gosh, that's really interesting and probably not the first thing people think about when they think about the impacts of extreme weather like this. Andrea, are there any other ways to ensure that folks stay safe in extreme heat?

Garcia: Well, if you can, the best thing is to stay inside in an air-conditioned environment. If you don't have access to an air conditioner at home, visiting a cooling center such as a library. If you must be outside, try to go in the early morning or late evening when it's cooler. Drink plenty of water, stay in the shade as much as possible, and keep your electrolytes replenished with sports drink, electrolyte-infused beverages, fruits and leafy greens. And loose-fitting clothing with lighter colors that reflect the sun can also be beneficial.

Unger: Andrea, when we think about heat-related illnesses, are there any specific symptoms that people should watch out for?

Garcia: Well, symptoms of heat exhaustion include heavy sweating, cold, pale or clammy skin, headaches, nausea or vomiting. People may also experience muscle cramps and feel dizzy or fatigued. In more serious cases, overheating can include or lead to heat stroke. And according to the CDC, if you have heat stroke, your skin may be red, hot, dry or damp. Heat stroke can also cause confusion or a persistent headache, and it may even lead some to lose consciousness. It is important to get medical help immediately if you experience any of these symptoms.

Unger: All right, that's good guidance for the really hot weather out there. Andrea, let's turn our attention to a subject we haven't talked about in a little bit and maybe more of an issue in the summer months, and that is mpox. What's the latest there?

Garcia: Well, as we know, June is Pride month. And in keeping with that, the CDC has stepped up its campaign to get those at higher risk vaccinated. As you recall, back when we had our initial mpox outbreak in 2022, vaccines were in short supply. We saw many people waiting in long lines to receive only one of what was supposed to be a two-dose vaccine regimen, because the thinking was that some vaccine is better than no vaccine.

However, today, doses are more readily available. And in keeping with this, the CDC is working with the HHS Office of the Assistant Secretary of Health, local organizations and community partners on what it calls the Summer of Pride Initiative. And that's a campaign to remind people that, although mpox case numbers have declined significantly, the threat has not completely disappeared.

Unger: Speaking of reminding, can you remind us of how mpox is spread?

Garcia: Well, I think it's important to remember that anyone can get mpox. But according to recent case reports, 90% of those who got mpox in the U.S. during that 2022 outbreak who reported their sexual orientation were men who identified as gay or bisexual. And nearly all of those who got sick were unvaccinated. Mpox is a viral disease. It can spread easily between people. And according to the WHO, it's largely spread through close contact—so touching, kissing, sex—as well as contaminated materials, like sheets, clothing and needles. Symptoms include a fever, painful rash, headache, muscle and back pain, low energy and enlarged lymph nodes.

Unger: Andrea, are we actually seeing numbers climb again or is this just kind of getting out ahead of the problem, so to speak?

Garcia: Well, case reports, for the most part, remain relatively stable here in the U.S., and they're nowhere near as high as they were in 2022. There was a report published in May, and there were about 59 new cases per week reported in the U.S. as of the end of April. That compares to about 3,000 new cases reported per week between mid-July and late August at that height of the 2022 outbreak.

I think what people may not realize is that it has continued to circulate at low levels since then, and some cases have likely gone unreported. The good news is, in a recent report, there was confirmation that two doses of the Jynneos vaccine are highly effective in preventing many mpox cases. And if someone who was vaccinated did get sick, the vaccine significantly reduced the severity of symptoms. So it's important that—because this isn't a disease that anyone wants to get, and it can be serious in some cases and even deadly.

Unger: And I think from our prior discussions, we've talked about how there are different forms of the disease, some of which are more deadly than others. Can you remind us about that difference?

Garcia: That's right, Todd. So just to give this some perspective, about 10% of people who got sick with mpox in the U.S. in the latest outbreak were hospitalized, and five died since October. As you mentioned, there is also the threat of a deadlier version known as Clade I, and we've discussed that in previous episodes. Clade I carries a case fatality rate of up to 10% compared with 0.1% to 3.6% for Clade II, and Clade II is the version that's currently circulating here in the U.S.

CDC has reported that Clade I is more transmissible, and while it hasn't made its way to the U.S. yet, it is the cause of an outbreak that the CDC is monitoring in the Democratic Republic of Congo. We talked about that several weeks ago. Right now, the best thing that people who are at high risk can do is take advantage of the preventive measures we have available and get vaccinated.

Unger: Absolutely. Good to know. All right, Andrea, let's turn to a different headline that we've been talking about a lot lately. That's bird flu. What is the latest update since we last talked?

Garcia: Well, the big headline over the past few days was a study published Friday in the New England Journal of Medicine. And according to new research that was co-authored by scientists at the NIH, levels of H5N1, avian influenza, rapidly declined when heated to pasteurization temperatures, but a small, detectable quantity of infectious H5N1 bird flu virus was able to survive a common approach to pasteurizing milk.

These findings were based on experiments run at the agency's lab. The researchers noted that this is not the same as finding infectious virus in milk from grocery stores. So far, officials have not detected live infectious virus in any supermarket milk samples, and that's important to remind people of that.

Unger: So what exactly does it mean, then, for our milk supply?

Garcia: Well, the FDA did release a statement that said the study reflected experimental conditions and should not be used to draw any conclusions about the safety of the U.S. milk supply. There was a CBS news article that noted experimental conditions do differ from real-world conditions in meaningful ways. And an example they gave is that in the real world, milk from infectious cows is likely being mixed with milk from healthy cows, and that's diluting the virus and making it less likely that there would be enough of it to survive.

The FDA is currently looking at pasteurization in its own studies, and a spokesperson said that its testing data so far shows that the pasteurization process used by U.S. dairy companies are effective at killing H5N1. We do know that heat kills the virus. Proper pasteurization, combined with efforts to keep H5N1-positive milk from entering the pipeline in the first place, should help keep our milk supply safe. But obviously, this is something we're going to continue to track and report on as more data becomes available.

Unger: All right. Well, that looks like it's all we've got for this week. Andrea, thanks so much for being here and keeping us informed. If you found this discussion valuable, you can support more programming like it by becoming an AMA member at We'll be back soon with another AMA Update. In the meantime, you can find all our videos and podcasts at 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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