Malaria cases in the United States are increasing and Lyme Disease cases are appearing as far west as Michigan. Is climate change to blame or are there other factors at play? With insights from U.T. Austin pediatric infectious disease specialist Dr. Nael Mhaissen, we don a pair of nitrile gloves and get up and close with microbes and the vectors that bear them.
Learning Objective: By the end of this episode, pediatric residents will be able to recognize the relationship between a warming climate and the geographical spread of vector-borne disease such as malaria and Lyme Disease, as well as non-vector-borne infectious agents such as diarrheal illness and fungal infections.
Guests
Nael Mhaissen, MDPediatric Infectious Disease Physician at Dell Children's Medical Center
Hosts
Sophia Gauthier, MD, MSPediatric Hospital Medicine Fellow at Dell Medical School at University of Texas at Austin
Graham Aufricht, MDPediatric Emergency Medicine Fellow at Dell Medical School at the University of Texas at Austin
[00:00:00] Sophia Gauthier: Welcome back. I am Sophia Gauthier. And I’m Graham Aufricht. We are pediatricians and hosts of this podcast, Clinicians, Kids, and the Changing Climate. So I’ve brought an article in from Time magazine.
[00:00:15] Graham Aufricht: So we are looking at a photo of a mosquito with a massive belly taking a blood meal. Delicious. I
[00:00:22] Sophia Gauthier: can’t stop looking at it.
Neither can I. Okay, so this mosquito is the accompanying photograph from an article published back in 2014 by Time Magazine, and it’s titled, quote, Malaria Climbs Mountains as the Climate Warms. I still can’t stop
looking
[00:00:37] Graham Aufricht: at this thing.
[00:00:38] Sophia Gauthier: I know, it’s really distracting. I’m sorry. Okay, but if we scroll down, we don’t have to look at it anymore.
So this article is about a study published in Science the same year. Now, malaria incidence has fallen by a third in the last 20 years, thanks to renewed efforts to control mosquito populations. However, these researchers found that the geographic range of the malaria mosquito vector, the anopheles mosquito, right?
Yeah, I’m glad you said that because I could not remember. I was just going to gloss over it. But yeah, the Anopheles mosquito habitat is expanding with each warmer year. So
[00:01:14] Graham Aufricht: how big of a
[00:01:15] Sophia Gauthier: problem is this? Well, nowadays we often think about malaria as a disease of tropical equatorial countries. It’s the cause of over a half million deaths per year worldwide.
And in 2021, 77 percent of those deaths were in children under the age of five. So it really should be thought of as a disease of particular interest to the pediatric world. However, even in tropical climates, malaria is much less prevalent at high altitudes because the cooler weather makes it more difficult for the Anopheles mosquito vector to thrive, as well as the Plasmodium parasite to be transmitted.
[00:01:50] Graham Aufricht: So you’re saying that in the malaria belt. Even with advances in mosquito population control, high altitude places that were once protected from malaria are now at risk?
[00:02:00] Sophia Gauthier: Correct. Although I do have some good news as well. As of July this year, as part of the Malaria Vaccine Implementation Program, 18 million doses of the malaria vaccine Mosquirix will be allocated to 12 African countries to help fight this disease.
[00:02:14] Graham Aufricht: Okay. Now… You and I are both interested in global health, but many of our listeners will practice mainly in the U. S. How can this information impact those patient populations?
[00:02:24] Sophia Gauthier: So malaria was successfully eradicated from the U. S. in the early 1950s. This was as a result of the establishment of what is now known as the CDC.
They had improvements in sanitation, medical care and insecticide use. However, the incidence of cases, which, by the way, is still incredibly low in the U. S. is rising, and most of these cases are imported. You know, we live in a world of increasing globalization, but some of these cases are postulated to be due to local spread, such as cases of what we call airport malaria, where an infected mosquito hitchhikes overseas from an endemic area and bites an unsuspecting victim.
[00:03:01] Graham Aufricht: Hmm. So does that mean that the Anopheles mosquito that can transmit malaria still lives in the U. S.?
[00:03:06] Sophia Gauthier: Alive and thriving. Yikes. Exactly. For now, at least in the U. S., we rarely see malaria. But our next case study, however… I’m
[00:03:15] Graham Aufricht: guessing this is something
[00:03:16] Sophia Gauthier: more local? Yes. Every year in the United States, three to five hundred thousand people are affected by Lyme disease, which is caused
[00:03:24] Graham Aufricht: by…
The bacteria Borrelia burgdorferi. I’m
[00:03:27] Sophia Gauthier: so glad that you had to say that word and not me. I could never pronounce it. So this is the most common vector borne disease in the country. Particularly in children, right? Correct. This is another disease of pediatric interest because boys between the ages of 5 and 9 are at greatest risk.
And Lyme disease is spreading. Based on data from the CDC, C, the incidence and geographic spread of Lyme disease has been steadily increasing over the past 30 years. It is postulated that this is likely driven by climate change related extensions in the warm season, which promotes the proliferation of its vector, the black legged tick.
I consulted one of our subspecialists to learn some more.
[00:04:06] Nael Mhaissen: My name is Nael Mhaissen. I’m a pediatric infectious disease doctor at Dole Children’s Medical Center. So, we’re seeing Borrelia, the bacteria that causes Lyme disease in areas that we have not encountered before. And a lot of this has something to do with the change In climate and the areas where the deers or the, the deer tick that carries Borrelia is actually surviving.
So we’re seeing now areas in the Midwest, uh, that have Lyme disease. We are also starting to see spread of it in new areas in Michigan. So areas outside of the typical places where we usually see Lyme disease, such as Connecticut or New England area. So, that shifting epidemiology has a lot to do with climate change and how the animals that carry the infection or the ticks that carry the infection are surviving.
Okay.
[00:04:56] Graham Aufricht: So, a warming climate is driving geographic extension of vector borne diseases like malaria and Lyme disease. I know there are similar data regarding other pathogens like dengue virus. What about non vector borne infectious disease?
[00:05:10] Sophia Gauthier: There are also associations between high temperatures and diarrheal illnesses like cholera, salmonella, and E.
coli. And certainly climate associated extreme weather events that cause flooding can overwhelm sewer systems and compound that risk. But I also wanted to highlight fungi. Fungi are particularly challenging because there are no fungal vaccines in existence, the number of antifungal agents available is limited, and fungi can cause disease without requiring host to host contact to spread.
What do we know about the impacts of climate change on the risks of fungal infections?
[00:05:46] Nael Mhaissen: So that’s exactly true. Not just that, the fungal infections are also challenging because of the lack of diagnostic methodologies that we have to make such diagnoses. Climate change is affecting different infections, whether it’s bacteria, viruses, or even fungi, in different manners.
One example is coccidioidomycosis. This is the endemic mycosis, endemic fungal infection. The causes valley fever. So that one, uh, is a fungi that actually prefers the dry desert like weather. And when you see the drought expanding in areas like California, Washington, Arizona, and even parts of Texas, you start to see new cases, for example, of coccidioidomycosis in areas where these infections were not encountered before.
And that’s just one example.
[00:06:34] Graham Aufricht: Let’s wrap up and discuss key takeaways from this episode and opportunities for action. So
[00:06:40] Sophia Gauthier: first, a warming climate contributes to the geographic and altitudinal spread of various vector borne infectious agents, such as malaria and Lyme disease.
[00:06:48] Graham Aufricht: Second, higher temperatures are associated with higher rates of diarrheal illness, such as cholera and E.
[00:06:54] Sophia Gauthier: coli. And lastly, climate is certainly contributing to the spread of fungal infections, as well as acting as an evolutionary pressure towards new species of fungi.
[00:07:03] Graham Aufricht: So what can we do as
[00:07:05] Sophia Gauthier: pediatricians? So we can provide lots of anticipatory guidance for protecting against vector borne disease, such as wearing 30 percent DEET insect repellent once daily in kids over two months of
[00:07:15] Graham Aufricht: age.
We can screen children for water insecurity. For example, children who drink untreated well water are at a higher risk of waterborne illness.
[00:07:24] Sophia Gauthier: Awareness can play a big role as well. It’s important as physicians to understand that infectious illnesses are no longer limited to their classic textbook regions.
[00:07:34] Graham Aufricht: Alright, that’s a wrap for today. Join us for our next episode on extreme weather and disaster preparedness.
[00:07:41] Sophia Gauthier: This podcast was researched and written by myself, Dr. Sophia Gauthier. A massive thank you to my friend and co host, Dr. Graham Aufricht, as well as our guest, Dr. Nael Mhaissen, for his expertise in pediatric infectious disease.
The podcast was produced by the fantastic audio engineers at the University of Texas at Austin Liberal Arts Instructional Technology Services team with funding via a pediatric medical education grant and instructional support from the Medical Education Fellowship at the University of Texas Dell Medical School.