- large roundworm
- worldwide distribution; Highest prevalence
in tropical areas and areas with inadequate sanitation.
- Most common helminthic infection
worldwide; this worm is thought to infect approximately 4 million Americans
and an estimated 1.4 billion individuals worldwide.
- Occurs in rural areas of Southeastern USA.
- Although infections may cause stunted growth, adult worms usually cause no
- the most common presentation is the
passage of a worm in the stool.
- Although most infected individuals are
asymptomatic, some present with coughing, wheezing, hemoptysis, colicky
abdominal pain, or bilious emesis.
- High worm burdens may cause abdominal pain and intestinal obstruction.
Biliary or complete intestinal may occur.
- transmitted in a fecal-oral manner,
primarily from the ingestion of food contaminated with parasite eggs.
- Ingestion of infective eggs from contaminated soil results in infection,
which is often asymptomatic.
- after ingestion Ascaris larvae hatch and
are released into the intestine, Adult worms live in the small intestine from where they migrate to the lungs.
During the lung phase of larval migration, pulmonary symptoms can occur
(cough, dyspnea, hemoptysis, eosinophilic pneumonitis - Loeffler’s syndrome).
- After 1-2 weeks, the partially developed
larvae ascend the trachea and are reswallowed.
- They then develop into mature worms and
produce eggs that are excreted in the stool.
- The worms can reach up to 30 cm in length.
- Migrating adult worms may cause symptomatic occlusion of thebiliarytract
or oral expulsion.
- Ova and parasites may be found in the
stool. Adult worms are occasionally passed in the stool or through the mouth
- oral mebendazole 100 mg administered twice
a day for 2 days or
- oral albendazole 400 mg given once, with
another dose given at 3 weeks.
- Flaccid paralyzing agents, such as
piperazine citrate, are preferred when intestinal obstruction is suspected.
- Pyrantel pamoate, a spastic paralyzing
agent, is easier to administer as a single dose, but it increases the risk of
Follow-up: Re-examine stool 3 weeks after therapy confirm treatment success.
For more information about ascariasis, see the eMedicine articles Ascariasis
(within the Pediatrics specialty) and Ascariasis and Nematode Infections
(within the Internal Medicine specialty).
CHLA Board Review 2005