Scary Ascaris


We have discussed many commonly encountered issues throughout the Ped EM Morsels, but many of us stay interested in our jobs because of the significant vastness of topics that we encounter.  When the child’s foster mother told me that she “found a worm in the diaper,” I will admit that I became immediately more “interested” than usual.  Certainly this was not going to lead to a Delayed Sequence Intubation and I was not going to have to recall how to work up Incomplete Kawasaki Disease, but it was something that I had not thought through thoroughly since taking written board exams.  I guess those board examinations have a purpose after all…

Ascaris lumbricoides

  • Intestinal nematode (think back to medical school… you can do it)
  • One of the most common human helminthic infections worldwide.
    • Estimated to affect more than 1 BILLION people.
    • Most prevalent in tropical environments.
    • Also seen where sanitation is suboptimal.
  • Children 2 years to 10 years of age are the most commonly effected, but all ages can be involved.
  • Can be transmitted by contaminated water or food or by children playing in contaminated soild!

Ascaris Fascinating Life-cycle

This is the part that makes me think a Scary Halloween Movie could be written about this weird worm!

  • The adult worm lives in the lumen of the human small intestine.
    • You need to have both male and female worms present to generate viable eggs.
    • Females will still make eggs without males present (and these can be detected in stool studies).
    • If only males are present, no eggs will be made – so you won’t detect them on stool studies.
  • The fertilized eggs are passed in the stool and can hang out in the soil for up to 10 years!
  • A unsuspecting human then ingests the eggs, which hatch in the small intestine.

Here’s the weird and wild part…

  • The released larvae then migrate through the intestinal wall and travel via the bloodstream or the lymphatics to the lungs!
  • Sometimes, they get lost and migrate to other organs (ex, brain).
  • In the alveoli, they mature – takes about 10 days.
  • When matured, they climb up the bronchial tree (this makes my get queasy just thinking about it).
  • They are then swallowed back into the GI tract (think about that… they have to climb up past your vocal cords and then jump down the esophagus!!!!).
  • Once in the small intestine again, they mature to adults and start the cycle over.

Clinical Presentations

  • Most often the presence of the worms is not apparent as the condition is usually ASYMPTOMATIC (also kind of scary).
  • Naturally, with more worms being present, there is a great chance of having symptoms.
  • Symptoms, when present, tend to occur during the migration of the larvae or when there is a large adult worm burden (yuk!).
  • Intestinal Symptoms
    • Anorexia, nausea, and diarrhea have all been attributed to Ascaris infections.
    • Can also lead to nutritional deficits.
  • Intestinal Obstruction
    • There are plenty of gross pictures online that depict large worm burdens.
    • When there is a ton of worm bodies in the small intestine, it only seems natural that there would be intestinal obstruction.
    • In some countries, Ascaris induced intestinal obstruction is the leading cause of abdominal surgical emergency.
    • Most commonly seen in the kids 1-5 years of age.
    • Emesis may contain worms (now that is something you can consider for this Halloween!!)
    • Endoscopy or surgery may be needed to clear the obstruction.
  • Hepatobiliary System Involvement
    • Worms can migrate into the biliary tree and cause obstructive processes there as well.
    • May lead to biliary colic, cholecystitis, cholangitis, obstructive jaundice.
    • May also lead to biliary tree perforation and peritonitis.
    • Can also obstruct the pancreatic duct and lead to pancreatitis.
  • Pulmonary Symptoms
    • Larval migration leads to eosinophilia and an associated pneumonitis.
    • This is called Loeffler’s Syndrome, but Loeffler’s Syndrome does not have to be due to Ascaris infection (hypersensitivity reaction to other parasites or drugs can do it also).


Treatment Options

  • Albendazole (400 mg po ONCE)
    • Shown to be effective in almost all of the cases!
  • Ivermectin (200 mcg/kg)
    • Second-line.
  • Both of these affect the adult worms only… so, if there are larvae still handing around, they will survive and mature.
  • Re-evaluation in 2-3 months is, thus, necessary.

Starr MC, Montgomery SP. Soil-transmitted helminthiasis in the United States: a systematic review—1940–2010. Am J Trop Med Hyg 2011;85:680–4.

Khuroo MS. Ascariasis. Gastro Clin North Am. 1996; 25(3): 553-577.


Sean M. Fox
Sean M. Fox
Articles: 583

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