High-Yield Information on Intestinal Nematodes

Intestinal nematodes pose memorization challenges, but a clever poem aids in recalling key symptoms and treatments.

### Mastering Intestinal Nematodes: Key Insights and Mnemonics
* 📚 Many medical students struggle to retain **high-yield information** about intestinal nematodes due to a greater focus on **bacteria and viruses** during their studies.
* 🪱 This video covers important nematodes such as **Enterobius vermicularis**, **Ascaris lumbricoides**, **Strongyloides stercoralis**, **Ancylostoma duodenale**, **Necator americanus**, **Trichinella spiralis**, and **Trichuris trichiura**, providing essential details including **treatment** and **epidemiology**.
* 🔍 A significant point to remember is that intestinal nematodes are **helminthic organisms**, typically tubular with **both digestive openings**, and often transmitted via **contaminated soil**.
* 💡 The immune response to these infections involves eosinophils, which may indicate **helminthic infections** if elevated levels are found in lab results.
* 🩺 For **Enterobius vermicularis**, the key symptoms include **perianal pruritus** diagnosed by the **cellophane tape test**, while **Ascaris lumbricoides** is associated with **obstruction of tubular structures** and **eosinophilia**.
* 🌍 Strongyloides stercoralis is transmitted transcutaneously from contaminated soil, leading to **GI and respiratory symptoms**, whereas Ancylostoma duodenale and Necator americanus cause **cutaneous larvae migrans and anemia** due to their attachment to **intestinal capillaries**.
* 🍖 Trichinella spiralis is contracted through undercooked pork, leading to **myalgia and periorbital edema** as it migrates to muscle tissues.
* 📜 To aid memorization, the speaker offers a mnemonic poem summarizing the key associations with each nematode, emphasizing that all these infections are treated with **bendazole**.

In this video, I will teach you all of the high-yield information that you need to know about intestinal nematodes. Most often, medical students, PA students, NP students, wherever you are in your training, most people have difficulty committing the high-yield information about intestinal nematodes

to their brain. And my theory for that is because a lot of the bacteria, a lot of the viruses, that information shows up on exams a lot more often. And so people spend so much time and effort memorizing bacteria and viruses that by the time

they get to the helminthic infections and the helminthic pathogens, they really struggle to conceptualize this information and find a compartment in their brain to store all of this information. And so my goal in this video today is to, one, I'll go through all of

the intestinal nematodes that you see on this slide, and I'll teach you in a traditional way what you need to know, what's high yield, what buzzwords you should know, how it's treated, the epidemiology, etc. But then at the very

end of this video, I will give you my really cool pneumonic, which is, spoiler alert, it's actually a poem. It's an eight-sentence poem that you can say in about 15 to 20 seconds, which if you're really struggling to memorize things, you

can recite it back on test day and it might clue you into some of the really high-yield bits of information that you need to know. So in this video, we'll start by talking about all of the intestinal nematodes that you see on this slide: Enterobius vermicularis

Ascaris lumbricoides, Strongyloides stercoralis, Ancylostoma duodenale, Necator americanus, Trichinella spiralis, and Trichuris trichiura. Let's start with a brief overview just to establish and create a compartment or category for what we're

talking about. So all of the intestinal nematodes are known as helminthic organisms, which is a scientific way of saying that these are parasitic worms. Almost all of these worms are tubular; they have tubular digestive systems with openings at both ends, and as you'll see

the majority reside in the topsoil, and so often times the way that humans get infected with these helminthic intestinal nematodes is we come in contact with soil that has some trace of the organism. Now the important thing to know about the intestinal nematodes is that

the way that the human immune system fights them off is by utilizing eosinophils, and on your exam, you should understand that this could involve a type one or a type two hypersensitivity reaction. Type one involving neutralization with histamine and leukotrienes

and type two involving IgE-mediated attachment. Not too much to know there, but just keep in the back of your mind that if you're taking your exam and you get a lab printout with a high level of eosinophils, you want to

potentially associate that with fending off a helminthic organism or a helminthic infection. Let's get started with Enterobius vermicularis. So it's the ingestion of the pinworm eggs that causes the infection. So we're talking about fecal

oral transmission here the big buzzword and the big clinical symptom that you need to keep in the back of your mind is perianal pruritis in other words itching around the anal opening what happens here is that when the human who's infected with enterobius goes to sleep

at night the adult female worm in the intestine will migrate to the anal opening and there they will deposit thousands of eggs so from the human's perspective what that feels like is itching in the perianal area and so the way that this is diagnosed is with the

cellophane tape test and literally what happens is a piece of tape is placed over the anal opening and in the morning that piece of tape is examined and if there are eggs seen on that piece of cellophane tape that's a positive tape

test which is to say we know that an adult female worm must have laid eggs on that piece of tape at night and that would be how enterobius vermicularis is diagnosed the treatment is going to be bendazole so the big thing

that you want to take away from this slide for the purposes of exams is perianal pruritis diagnosed by the cellophane tape test that is enterobius ascaris lumbricoides you want to associate this with obstruction of tubular structures

and by tubular structures I mean areas that stem from different organs with material passing through so we're talking about things like pancreatitis or inflammation of the pancreas due to obstruction of the tubular lumen that leaves the pancreas cholecystitis due to inflammation of the

gallbladder because of obstruction of the tubular lumen that leaves the gallbladder, etc., etc. So, ascaris lumbricoides, think obstruction of any kind of lumen. This can also cause pneumonitis if the eggs migrate to the lungs, and of course, 

expect to see eosinophilia, like, like I talked about in the overview slide. Transmission here: fecal-oral. And diagnosis is going to be made from the stool exam for ova and parasites. So, literally, we will be looking at the feces, looking at the stool, and trying to 

determine if there are ova and parasites in the stool. This is also treated with bendazole. So, the big takeaway for ascaris lumbricoides is obstruction of tubular structure, so you can get inflammation of various organs like the pancreas, like 

the gallbladder, you can get a small bowel obstruction because the lumen that leave or are part of inherently those organs get obstructed, and that causes inflammation. That is Ascaris lumbricoides. Now, let's move on to Str

Strongyloides stercoralis. So, as I talked about in the overview slide, a lot of the infection of intestinal nematodes is due to contaminated soil, and so here is an example of transcutaneous infection. So, the larvae are in fecal 

contaminated soil, and when a human walks on top of that fecal contaminated soil, the larvae will penetrate the skin and cause infection. So, the big things you want to look out for here with Strongyloides are GI symptoms and respiratory symptoms. Now, the GI symptoms tend to be 

non-specific and there's no individual symptom you necessarily need to memorize. Same for the respiratory symptoms, it's going to be things like cough. Basically, if you see somebody struggling with diarrhea, abdominal pain, or cough and some systemic symptoms, that's sort of

non-specifically referring to GI and respiratory symptoms. So you would want to think about Strongyloides. There's no pathognomonic buzzword here that you necessarily need to know. The one thing that I would point out, and it's not

necessarily attributable or pathognomonic just to Strongyloides, is something called Löffler's syndrome, which is basically eosinophilic pneumonia. This can also cause a superinfection. So what I'm hinting at here is

that with Strongyloides stercoralis, there's no clinical symptom that I want you to necessarily memorize. More so, just understand that the route of infection is transcutaneous due to fecal-contaminated soil. Some risk factors for Strongyloides that could help you if

you're really struggling on your exam are immunosuppressed patients, patients with HIV, patients with HTLV-1, and patients with a history of alcoholism. These are all risk factors. So if you're really gunning for a perfect score, then perhaps you memorize these.

But otherwise, I wouldn't concern yourself too much with that information because the infection is transcutaneous and it comes through the soil. There are also occupational risk factors, so anybody who farms, mines, or does general fieldwork are more likely to step on fecal-contaminated soil and therefore

get the infection and the treatment here is going to be bendazole and if you can't use bendazole you can use Ivermectin so strongyloides when you're memorizing this for your exam I would really just focus on the transcutaneous piece know

that anybody who works in soil is more likely to get it otherwise I wouldn't concern yourself too much with any other buzzwords now we'll move on to Ancylostoma duodenale and Necator americanus so just like we just talked about these two are an

example of transcutaneous infection where fecal contaminated soil comes in contact with human skin and then the infection penetrates the skin and that is the way that it gets into the human the way that this works is that it's an ascending infection so it works its way

up because most people get it first in their skin usually in their feet but not always it works its way up and eventually it makes its way to the respiratory tree then the human will cough bringing it up at the junction of the trachea and the

esophagus the patient or the human will swallow and then that puts the infection into the GI system causing the systemic manifestations so there are two things that you want to look out for with both Ancylostoma duodenale and Necator americanus one is called cutaneous

larvae migrans which is a really fancy way of saying an itchy snake-like rash and specifically that rash is going to be where the skin contacts the soil so if on your exam you see an image of a snake-like which is serpiginous rash that's a

little bit erupted, meaning that some parts of it are raised, and in the vignette they tell you it's pruritic or itchy. That is screaming at you that it's an intestinal nematode, and you want to think about Ancylostoma or

Necator americanus. The other thing to keep in mind is anemia and protein loss. So, because again, this is an ascending infection when it makes its way to the intestinal phase, once it's in the GI system, these worms, the adult worms, literally attach to the intestinal

capillaries and cause them to rupture. And when we rupture capillaries, that means we have problems absorbing things, so we see protein loss, and it means that we have problems regulating hemoglobin because blood flow is affected, and therefore we have anemia. So, anemia and

protein loss are because the adult worms latch onto and bite the intestinal capillaries. Treatment here: bendazole. If you can't use bendazole, pyrantel pamoate. So, the bottom line here for Ancylostoma and Necator americanus, both are grouped together, you want to know two things: one, the itchy

snake-like, slightly erupted rash where the soil that's infected or contaminated, I should say, meets the skin, and two, anemia and protein loss because of worms literally biting onto and rupturing the intestinal capillaries. That is Ancylostoma duodenale and Necator

americanus. Now let's move on to Trichinella spiralis. This is caused by consuming raw or undercooked pork. It can be from some other meats and other game, but generally on your exam on USMLE or COMLEX, it's going to be pork. The

Infection occurs in two phases: there's the **enteric** phase and there's the systemic phase. The **enteric** phase is caused by pepsin and hydrochloric acid causing the release of the **larvae**. Then there's the systemic phase where the **larvae** will

travel through the lymphatics, through the blood, and ultimately find its way into some muscle tissue. That muscle tissue will either be in the myocardium, the brain, or the skeletal muscle. And the reason that it's going to end up in the heart, the brain, or the skeletal muscle

is because those organs or those areas have an extremely high oxygen content that *Trichinella* needs to survive. So what you're going to see on your exam clinically are non-specific GI symptoms, but the big one and the one that you absolutely need to know or memorize is

myalgia, because this is going to find its way to muscle tissue. Muscle equals myalgia, muscle cramps. You absolutely need to know that. You can get some non-specific symptoms like fever, chills, fatigue, but another big one is periorbital edema. So if you're looking

at this slide and you're like, 'Dude, just tell me what I should memorize,' my answer is muscle tissue, myalgia, and periorbital edema. If you can keep those three things associated with *Trichinella spiralis* in your brain, you're golden. So again, I'll say it

one more time because I'm hammering it into your neurons: *Trichinella spiralis*, think myocardium, brain, and skeletal muscle. Those are all tissues with very high oxygen content because *Trichinella* is going to muscle. You're going to see myalgia. Also, back of your mind

periorbital edema treatment for TR canella bendazoles and that's it so let's just move on. Remember muscles, myalgia, edema. Now we'll talk about trichostrongylus. It's a pretty curious name, no pun intended. So this is fecal oral

transmission most often in warm, humid and hot climates. Two things you want to look at on your exam for trichostrongylus: rectal bleeding and rectal prolapse. Rectal bleeding and rectal prolapse, especially in children. Rectal prolapse, that's the big buzzword here. If you see

rectal prolapse as it relates to a nematode, the answer is trichostrongylus. You're done. You can see some other GI symptoms like nocturnal passage of stools, painful diarrhea, painful defecation and mucusy stools. But on your

exam, they're going to give you rectal prolapse if they want you to pick trichostrongylus. If things are really severe, you can see anemia, poor malnutrition and failure to thrive. But again, they're going to give you rectal prolapse, so

that's what you want to know. Treatment is bendazole. So if you have made it through the roughly 15 to 20 minutes, however long that information took me to deliver to you, and you're like, 'I'm sorry, I just can't memorize that. I need a

pneumonic.' Here is my nematode poem. So I'm going to do this in my best Shakespeare voice, um, because I think that if you can't find the brain space, you can just memorize this poem. What you'll notice here is that it is one

nematode per line of the poem The nematode is highlighted in red and the key buzzword or key symptom that you need to associate with the nematode is highlighted in blue in the same line so here we go enter eggs in the anus will make it

itchy pork makes you spiral the muscle gets glitchy strong from the soil causes poops and coughs the ankle of America makes capillary sloth Tri curious indeed the prolapse protrudes them Lumber in the tubes this will include them the nematode poem that is all treat all of

these worms with bendol and I want you to notice that we're talking about the intestinal nematodes and line by line you can associate the words in red with the corresponding nematode so for example enter eggs in the anus will make it itchy enter for enterobius eggs in

the anus will make it itchy that's helping you remember that the key buzzword or the key Association is perianal pruritis and so go through my poem and memorize this if you want to because it gives you the one key

buzzword that I think you should memorize so one more time for everybody at home enter eggs in the anus will make it itchy pork makes you spiral the muscle gets glitchy wrong from the soil causes poops and coughs the ankle of

America makes capillary sloth Tri curious indeed the prolapse protrudes then Lumber in the tubes this will allude them the nematode poem that is all treat all of these worms with bendol good luck

Nematodes (INTESTINAL parasites)

Dirty Medicine

Introduction and Overview of Intestinal Nematodes

Video focuses on high-yield information about intestinal nematodes, a topic often difficult for students to memorize.

Students struggle due to greater emphasis on bacteria and viruses in their studies.

Video will cover intestinal nematodes traditionally and with a mnemonic poem.

Nematodes covered: Enterobius vermicularis, Ascaris lumbricoides, Strongyloides stercoralis, Ancylostoma duodenale, Necator americanus, Trichinella spiralis, and Trichuris trichiura.

Intestinal nematodes are helminthic organisms (parasitic worms), mostly tubular, residing in topsoil, and fought off by eosinophils in the human immune system, potentially involving type 1 or 2 hypersensitivity reactions.

Specific Intestinal Nematodes: Enterobius vermicularis, Ascaris lumbricoides, Strongyloides stercoralis

Enterobius vermicularis: Fecal-oral transmission, perianal pruritis (itching), diagnosed by cellophane tape test, treated with bendazole.

Ascaris lumbricoides: Obstruction of tubular structures (pancreatitis, cholecystitis), pneumonitis, eosinophilia, fecal-oral transmission, diagnosed by stool exam, treated with bendazole.

Strongyloides stercoralis: Transcutaneous infection from fecal-contaminated soil, GI and respiratory symptoms, Löffler's syndrome (eosinophilic pneumonia), superinfection possible, risk factors include immunosuppression, HIV, HTLV-1, alcoholism, and occupational exposure, treated with bendazole or ivermectin.

Specific Intestinal Nematodes: Ancylostoma duodenale, Necator americanus, Trichinella spiralis

Ancylostoma duodenale and Necator americanus: Transcutaneous infection, ascending infection, cutaneous larvae migrans (itchy snake-like rash), anemia, and protein loss, treated with bendazole or pyrantel pamoate.

Trichinella spiralis: Consumption of raw or undercooked pork, enteric and systemic phases, larvae travel to muscle tissue (myocardium, brain, skeletal muscle), non-specific GI symptoms, myalgia, periorbital edema, treated with bendazole.

Specific Intestinal Nematode: Trichuris trichiura and Mnemonic Poem

Trichuris trichiura: Fecal-oral transmission, rectal bleeding, rectal prolapse (especially in children), other GI symptoms, anemia, malnutrition, treated with bendazole.

Mnemonic poem summarizing key features of each nematode, with nematode name and key symptom highlighted.