Episode transcript
Time stamps
0:32 – Introduction to stinging insect venom allergy.
2:52 – Triggers and symptoms.
5:31 - Systematic symptoms.
6:42 - Explanation of tryptase and conditions for higher risk of reaction.
8:07 – Diagnosing stinging insect venom allergy and potential pitfalls.
11:05 - Why is it important to know which insect is causing a reaction?
12:56 - How effective is venom immunotherapy?
13:40 - The role of tryptase.
14:46 - How can primary care providers optimize patient management?
15:58 - When should patients be tested for stinging insect allergies sensitization?
Announcer:
ImmunoCAST is brought to you by Thermo Fisher Scientific, creators of ImmunoCAP™ Specific IgE Diagnostics and Phadia™ Laboratory Systems.
Gary:
I'm Gary Falcetano, a licensed PA with over 11 years experience in allergy and immunology.
Luke:
And I'm Luke Lemons, with over five years of experience writing for healthcare providers and educating on allergies. You're listening to ImmunoCAST, your source for medically and scientifically-backed allergy insights. Today on ImmunoCAST, we're going to be talking about the latest buzz around stinging insect allergy. It's also called insect venom allergy.
Gary:
Yeah. As the weather begins to heat up and bugs start to come out, it may be more and more common that we start seeing patients in the clinic who have potentially had a bee, wasp, or fire ant allergic reaction.
Luke:
And that's why on this Fireside Chat episode, we're excited to share with our primary care audience some of the perhaps lesser-known information on this type of allergy, as well as the role of molecular allergen components involved in reactions and how effective venom immunotherapy is for patients who complete a full course because some HCPs out there may not know the full value of that therapy. Is that right, Gary?
Gary:
Yeah. I recently, at an allergy Congress, had the opportunity to listen to Dr. David Golden, one of the preeminent experts on this topic. And he actually said that actually, from an HCP perspective, greater than 90% of non-allergists are not aware of the full potential of venom immunotherapy and just how effective it is and its availability.
Luke:
But before we get into venom immunotherapy, I want to go back to what you had mentioned, Gary, around what stinging insect allergy is, and you had said bee, wasp, and fire ant. And I'm glad you mentioned that because oftentimes, we just think of the bee and the wasp.
Gary:
Yeah, exactly. And certainly for what are known as imported fire ants, we're seeing increasing allergy to them, especially in the southeastern portion of the United States where they were initially unintentionally imported to. And because of warming climates and the general increase in the range that we've been finding them, we're starting to see imported fire ants up into the central area of the country as well.
Luke:
And we actually see that up to 95% of the general population report being stung by an insect like a fire ant or a honeybee or a wasp.
Gary:
Yeah. I know I certainly have been stung in the past without any severe reactions, just a small local reaction, but I think most of us have.
Luke:
Yeah. And I mean, the wasps, they'll sting you multiple times, the honeybees are only once, and the fire ants, they will sting multiple times as well. So why don't we go into what it looks like when they do sting and what the symptoms are of this allergy, Gary?
Gary:
Sure. And I think when you say multiple times, that can have several meanings as well, right? So we can have multiple stings, as you said, from wasps and fire ants from the same insect, but we can also have multiple creatures, multiple insects stinging at once. And that often happens especially with fire ants, where we can see hundreds of fire ants swarming to defend their nest. But you didn't want that fun fact, did you, Luke? You really wanted me to talk about symptoms though, right?
Luke:
No, I always appreciate a good fun fact out of nowhere. It's what makes this show what it is.
Gary:
No, absolutely. One more thing before I talk about symptoms, and I think this really plays into symptoms, is that another thing that Dr. Golden speaks to is there are a lot of patients who will have a pretty severe, even systemic, reaction and think it's a fluke and never even kind of complain about it or report it to their primary care providers or seek out any help because they think, "Oh, that was just a one-time thing." So I think it's important that from a patient perspective, we keep our level of awareness high and maybe even include it in our general preventative histories. Just like we would ask about any medication allergies, I think it's important to ask if they've ever had any severe reactions to insects.
Luke:
And so when you say that they experience these symptoms and maybe think it's a fluke, are we talking about small local reactions, large local reactions, systemic reactions? Why don't we break these down for our audience?
Gary:
I think it's all of the above because he even talked about severe reactions not getting reported. But in general, I mean, I think most of us have had a sting by one of these insects, and typically we have a small reaction, a couple of centimeters, it itches, it hurts, right? We have symptoms for maybe a day or so with that. The next level of reactions, though, are known as large local reactions. And these can be 10 centimeters, even more, and they tend to grow over time, over a
period of 24 to 48 hours, but they're all contiguous with the sting site. So that's why they continue to be labeled as a local reaction, even though they're a large local reaction.
Luke:
And for those patients who experience large local reactions, there's actually up to a 10% chance of having a systemic reaction. And so Gary, my question to you then is you had mentioned patients may not be telling their providers about these reactions and there's an increased risk that they may have a systemic reaction if they have a large local reaction. Can we talk a bit about what systemic looks like?
Gary:
Yeah. And I think just like any other severe allergic reaction, a lot of the symptoms are the same. So everything from periorbital edema, urticaria, angioedema, shortness of breath, dyspnea, stridor, wheeze, upper airway edema and swelling, nausea, vomiting, abdominal pain, everything that we would typically think as related to a severe allergic reaction. But those are all systemic signs, right? Typically, when we have two or more of those together, that's a definition of anaphylaxis. And especially with insect stings, hypotension by itself after a sting. So cardiovascular collapse/hypotension is another definition for anaphylaxis in those cases.
Luke:
There are certain conditions that put patients at a higher risk of severe reactions that I think our listeners and providers should know about. Previous severe stinging insect reactions, we had mentioned the large local reactions put patients at an elevated risk of systemic reactions. But there's also elevated tryptase levels from conditions like mastocytosis and hereditary alpha tryptasemia, right, Gary?
Gary:
Yeah. And even what are known as mast cell activation disorders, which aren't completely diagnosed as mastocytosis. So the number one ability to predict a future severe reaction is a prior severe reaction, right? After that, the only biomarker that's actually able to predict a future severe reaction is an elevated tryptase level.
Luke:
And can we do a recap, maybe for some of the listeners who aren't very familiar with tryptase in general, when it comes to why it's important in an allergic reaction? Can we do a little bit of an overview there?
Gary:
Tryptase is a preformed mediator that's released from mast cells when we experience an allergic reaction, but we typically have very low levels of tryptase in our circulation at all times. When you have mast cell disorders or you have hereditary alpha tryptasemia, we have elevated levels of tryptase that are what we call baseline levels, elevated baseline levels of tryptase. And in those patients, they're at higher risk for severe reactions of any form, but especially stinging insects.
Luke:
So if a patient does have elevated tryptase levels and they do have a stinging insect allergy, let's say a honeybee, and they're stung by honeybee, they're at a higher risk of having these systemic reactions. So knowing that tryptase level is also extremely important when looking at stinging insect allergy. I think this brings us to our next conversation around the diagnostic process and a potential pitfall in that.
Gary:
Sure. So I think the way that hymenoptera, or stinging insect allergy, is diagnosed, as we've said many times on this podcast, it always starts with history, right? History of a severe reaction. So patients should not be tested from a screening perspective. We sometimes get requests from parents before summer camp, "Can you test my children so I make sure they don't have a severe reaction to a bee while they're at summer camp?" That's not how this works, right? We only test when someone has a history of a systemic reaction. Maybe a large local in certain circumstances, but typically systemic reactions are the key to initiating testing. And then the testing is done with whole extracts. The current practice parameters that are issued by the American College and Academies of Allergy, Asthma, and Immunology state that we should test for all the available insect venoms, and that's usually about five different venoms, because people, number one, have a hard time identifying the exact insect that may have stung them. And also, even allergists may have sometimes have a difficulty identifying the culprit insects.
Luke:
And so if it is a suspected stinging insect allergy, you test for all the available insects in order to be certain on what may be causing these reactions. But we see that people are often sensitized to multiple species of these insects. Up to 50% of patients with venom allergies test positive for both honeybee and wasp, for example.
Gary:
Yeah, that's correct. And the reason for that is one of the kind of ubiquitous components that's in both honeybee and wasp venoms is CCDs, or cross-reactive carbohydrate determinants. And our listeners that remember our food allergy component episode, where we talked about CCDs as being one of those irrelevant oligosaccharides that people can become sensitized to from plants, the same is true here with venom. So they can cause a positive, whole extract, stinging insect venom, whether it be a bee or a wasp, but not be really clinically relevant and not indicate a true clinical allergy.
Luke:
And this is where narrowing a differential diagnosis gets a little gray because, to recap, you have to test for all the available stinging insects. And the fact that people cross-react between them both means that there may be a false positive, right, Gary, on one of these insects. For example, if somebody is tested and they come up positive for honeybee and wasp, one of those might be just wasp, but because of cross-reactivity, we wouldn't know.
Gary:
Yeah, that's correct. And I like to say they're irrelevant positivities because analytically, they're not false. It exists. There's antibodies there. But clinically, a patient may not respond with an allergic reaction because of that positivity.
Luke:
So then what's the next step then, Gary, in this diagnostic process? What can provide clarity to this gray zone of not knowing for certain which insect may be causing a reaction? And why is it important to know which insect is causing a reaction?
Gary:
Up until recently, especially in the US, we kind of had to stop there with whole extracts, whether they be done by skin testing or by in-vitro serological testing. But now, there is the availability of allergen component testing, just like we've talked about that on previous episodes. And what the components can actually help us do is tease out what is more a species-specific sensitization, indicating that's the insect that we need to be worried about and provide venom immunotherapy for, and what is an irrelevant sensitization, one that we may not do? So the real clinical benefit here is we're not immunizing people, if we decide to use venom immunotherapy, to insects they're not clinically allergic to, which means we can even decrease the amount of venom immunotherapy injections some people may be getting.
Luke:
So you're saying in the past, when a primary care provider, let's say, refers a patient to an allergist for venom immunotherapy, if they hadn't done testing with allergen components, that patient would be getting the bee venom immunotherapy, the WASP venom immunotherapy, but we wouldn't really know for certain. And so to me, that seems like a waste of resources.
Gary:
Yeah, but that's correlating the history with the whole extract positives. That's the best that we had and that's where even the current practice parameter, because it hasn't been updated in a while, still recommends that for immunizing for all of the things you're positive to. I think that may be changing in the next version of the practice parameters now that the venom components are available on a more widespread basis.
Luke:
And so testing with allergen components really helps provide that clarity into exactly which species is causing a reaction, which then leads on to more precise venom immunotherapy, which helps with patients becoming better. It's effective. Venom immunotherapy is effective too.
Gary:
So that's another one of the great kind of underappreciated things in the allergy world is just how effective venom immunotherapy is. For bee venom, it's about 80-84% effective, meaning protective against future reactions to stings, right? And with yellow jackets, that's in the 90-95% range, so this is a really effective treatment. And especially if you have people who are outdoor
kind of people, who spend a lot of time outdoors, it can be really important to get that protection on board to prevent future severe reactions.
Luke:
Yeah, never underestimate venom immunotherapy.
Gary:
Exactly.
Luke:
So we mentioned tryptase earlier though, Gary. Can we talk a little bit about the role of tryptase in this diagnostic process?
Gary:
Current guidelines and practice parameters recommend tryptase be tested anytime we're assessing a patient for a severe allergic reaction. So right along with testing for the venom whole extracts and, now, components, tryptase should be right there because we want to identify those patients who are at higher risk: those mast cell disease patients, those patients with alpha tryptasemia. And that has implications down the road too because, again, tryptase is predictive of more severe reactions in the future. It also informs how an allergist will do venom immunotherapy, so they need to take extra precautions during their buildup phase. And actually, the current thinking is if you have mastocytosis, you may need to be on lifelong venom immunotherapy.
Luke:
Oh, wow.
Gary:
Yeah, as opposed to a three to five year course, which is standard.
Luke:
And as we are talking about immunotherapy, of course that is a very allergist-focused topic, for primary care, Gary, in your experience, what are some things you can share related to stinging insects and how can primary care providers help patients and improve patient management?
Gary:
I think the biggest thing that we can really do is ask patients about previous reactions. Not just wait for them to come in after having a reaction, but ask them if they've had any reactions in the past. As I mentioned, most patients minimize it or they think it's a fluke. So including that in any preventative medicine history, I think, is really important. And then once they've been diagnosed, once we've diagnosed someone with a stinging insect allergy, obviously we're going to counsel on avoidance. We're going to be sure that they're prescribed an epinephrine autoinjector. And after that is convincing them that they really need to see a specialist to see an allergist for the consideration of venom immunotherapy.
Luke:
And so to go back to what you had said first, to ask them if they've experienced this sort of reaction, are you talking in a yearly physical? Asking that question, "Do you smoke? Have you been stung by a bee? What did it look like?" is that what you mean when you say ask?
Gary:
Yeah. Have you had any systemic and anything more than just a minor reaction to an insect sting?
Luke:
So when should patients be tested for stinging insect allergy sensitization?
Gary:
Yeah. So just to reiterate, it's not a screening test so they should only be tested if they've had a systemic reaction. And on a case-by-case basis, it may be recommended to test for a large local reaction, patients who have had a large local reaction as well. But in both those cases, again,
testing for everything we've talked about today, including the whole extracts, tryptase, and potentially the components, is really the most complete way to do an assessment.
Luke:
And that helps confirm if they have the allergy and may be candidates for venom immunotherapy. To recap this episode, we really just want to nail home that venom immunotherapy is effective and it can help patients. In order to optimize this therapy, it's understanding exactly what stinging insect is causing a reaction. That could be done through the aid of allergen component diagnostics. Don't underestimate venom immunotherapy. I know, Gary, when we were planning this episode, that was one thing you just kept saying.
Gary:
You have to find the patients that may be at risk. And absolutely, so many people are just unaware of how good it is. So get the appropriate patients to an allergist for venom immunotherapy, potentially saving lives, and really changing the way patients go about their lives, right? Not being completely afraid of always looking over their shoulder for that buzzing, stinging insect.
Luke:
And when it comes to the diagnostics that can help discover whether a patient is a good candidate for venom immunotherapy, we will have on this episode's webpage, at thermofisher.com/immunocast, a stinging insect interpretation guide with what those allergen components look like for each of these different species and what they mean for the patient, as well as the compendium for stinging insect allergy and practice parameters that we spoke a little bit about earlier in this episode. Thank you for listening to ImmunoCAST, and don't forget to subscribe and share this episode with your colleagues or patients if you want to help further educate.
Gary:
Absolutely. We'll see you next time.
Luke:
Bye.
Announcer:
ImmunoCAST is brought to you by ImmunoCAP Specific IgE Testing and Phadia Laboratory Systems, products of Thermo Fisher Scientific. For more information on allergies and Specific IgE Testing, please visit thermofisher.com/immunocast. Specific IgE Testing is an aid to healthcare providers in the diagnosis of allergy and cannot alone diagnose a clinical allergy. Clinical history alongside Specific IgE Testing is needed to diagnose a clinical allergy. The content of this podcast is not intended to be and should not be interpreted as or substitute professional medical advice, diagnosis, or treatment. Any medical questions pertaining to one's own health should be discussed with a healthcare provider.
