- Assalamu alaikom, welcome
again to another ATP video! - Today we will talk about a topic that
was heavily requested our lovely audience, you probably have guessed it right (or read
the title ;)). We will talk about Nematodes! Without further due, let’s
begin with a quick recap - Generally speaking, parasites can be
divided into two main groups: protozoa and helminths. Helminths can be subdivided into
two big groups: platyhelminths (flatworms), and nematodes (roundworms). And Platyhelminths
is further categorized into cestodes (tapeworms) and trematodes (flukes).
Keep in mind that worms’ infections are often accompanied by eosinophilia.
We know they seem a lot but the good news is that we in ATP have already done
videos on all of them, so you can easily cover them, don’t worry! In this video we will
complete our series and talk about nematodes! Nematodes are also known as
round worms. They vary in size; from some organisms being microscopic and up
to tens of centimeters in Ascaris lumbricoides. Not all nematodes are parasitic in nature,
and even the parasitic ones can be plant or -animal specific. Which means they do not
exhibit parasitic activity against humans. In this video we will focus on clinically
important, human-specific nematodes. We will divide the nematodes into two big groups:
- Intestinal (which mainly affect the GI tract)
- And Tissue related, which can affect different tissues (tissue
nematodes will be covered in another video) Their names are mouthful, so practice
saying them while we go along So let’s remember this mnemonic
for intestinal nematodes: EAASTT E: Enterobius vermicularis
A: Ascaris lumbricoides A: Ancylostoma & Necator americanus
S: Strongyloides stercoralis T: Trichinella spiralis
T: Trichuris trichiura Also, throughout this video
of intestinal nematodes, once we ask you about the treatment please
do not hesitate to say it’s a Bendazole, cuz statistically speaking
you’ll be 99.9% correct ;P The first nematode on the list
is: Enterobius vermicularis It is also known as pinworm, which can lead
to enterobiasis. In the developed countries, Enterobius vermicularis is the
most common type of worm infection. Life cycle and transmission:
It is transmitted feco-orally, when humans ingest contaminated food or hands
reach to the mouth that has pinworm eggs. So, it’s a human-to-human transmission. Then eggs mature into larvae
which live in the small intestine At night, gravid pinworm migrates
to perianal region to lay down eggs. Clinical importance:
Now for the symptoms: some people are asymptomatic, while others might show symptoms
that are particularly related to the perianal area, including itchiness and especially at
night, which can also affect the quality of sleep. It’s worth mentioning that children are among
the commonly affected age group with pinworms. Diagnosis: Enterobius vermicularis can
be diagnosed using tape test, which is applied on the perianal area. This test helps
visualizing pinworm eggs under the microscope. Look at this egg here, can you see its sharp
edge “v” link it to the V in vermicularis! Second nematode that we will be discussing is
Ascaris lumbricoides, a nematode that’s commonly responsible for causing ascariasis in different
countries and especially the tropical ones. Intro: Ascaris lumbricoides is
the longest intestinal nematode, thus its other name is the giant roundworm. Keep its size in mind because it will make perfect
sense when we discuss its clinical importance! Life cycle and transmission: Ascaris
lumbricoides is also transmitted feco-orally. After ingestion, eggs go to the intestine, and
then larvae ascend to reach to the lung where they mature. Mature forms of Ascaris lumbricoides
then go back again to the small intestine to enjoy the rest of its stay, while causing
many problems to its host. Such a bad guest Clinical importance:
Ascaris can causes ascarisis, Duh! This infection can be asymptomatic in some
patients while others can have GI symptoms (pain, nausea, vomiting, you name them). In addition,
due to its size it can obstruct many lumens, causing ileocecal valve and biliary obstruction.
Moreover, since part of its cycle is in the lung, it can cause respiratory problems (cough, bloody
sputum) in addition to Löffler's syndrome, which is characterized respiratory
symptoms + peripheral eosinophilia. Diagnosis: to diagnose Ascaris lumbricoides we
can perform stool studies, looking for its eggs. Under microscopy, these eggs have granular
patters and are oval in shape as you can see here. Third group that we will be discussing is
Ancylostoma species & Necator americanus Intro: you might be wondering why 2 at
the same time, but the answer is simple, that is, to make your life easy! Not only that,
but also because these 2 share many similarities so it’s better to group them together.
Ancylostoma includes many species. Acylosotma dudonale is the commonly
associated species with human infections, however, the rest of Ancylostoma species
can also cause diseases to humans These two are also known as Hookworms,
and if you look at their structure you’ll know why. Their heads are bend
a way which form a hook-like structure Life cycle and transmission: Unlike the
previous 2 nematodes, Ancylostoma species & Necator americanus are transmitted through skin
penetration mainly, and not through the feco-oral route. Their larvae (Filariform) can penetrate the
skin (foot usually) to invade the body. Using the blood as a vector, these larvae go to the lungs to
mature, and then subsequently migrate to the small intestine and start sucking
your blood. What a vampire! Clinical importance: for the clinical importance,
it’s worth mentioning that these worms often stay for a long time in your intestine, sucking
blood. So pt’s usually have iron deficiency anemia (due to blood loss). Moreover,
pts can have GI or respiratory symptoms. Cutaneous larva migrans is another problems
pts can have due to these hookworms. This happens once they penetrate the skin but get
entrapped in the superficial layers of the skin, away from blood vessels. It’s usually presents on
the foot and characterized by thread-like lesion, irritation and pruritis. Diagnosis: for diagnosis again we use stool
studies to help visualize eggs under microscopy And this brings us to the end of the first part
of intestinal nematodes. In the next part we will talk about Strongyloides stercoralis, Trichinella
spiralis, and finally, Trichuris trichiura. Don't forget to like, share, and subscribe
to receive our latest explanations. And as always, thanks for watching!