Ascariasis

Key Features

• Abdominal cramps and discomfort

• Large, white or reddish, round worms, or ova in the feces

• Ascaris lumbricoides infection is caused by contact with eggs or larvae that thrive in the moist soil of the tropics and subtropics

• Children infected with these worms are at increased risk for malnutrition, stunted growth, intellectual disability, and cognitive and education deficits

• Larvae hatch, penetrate the intestinal wall, enter the venous system, reach the alveoli, are coughed up the trachea and swallowed, returning to the small intestine, where they mature

• Female lays thousands of eggs daily

Clinical Findings

• Most infections are asymptomatic

• Moderate to heavy infections are associated with abdominal pain, weight loss, anorexia, diarrhea, and vomiting, and may lead to malnutrition

• Acute transient eosinophilic pneumonitis (Löffler syndrome) may occur during the larval migratory phase

• Appendicitis, common bile duct obstruction (resulting in biliary colic, cholangitis, or pancreatitis), or peritonitis can be caused by worm migration

Diagnosis

• Large roundworms (1.5–4 cm) are observed in the stool or by microscopic detection of the ova on stool examination

Treatment

• Highly effective regimens include

  • Albendazole (400 mg in a single dose, or 200 mg in children 1–2 years of age)

  • Mebendazole (100 mg twice a day for 3 days or 500 mg once)

  • Pyrantel pamoate (a single dose of 11 mg/kg; maximum 1 g)

• Piperazine (150 mg/kg initially, followed by six doses of 65 mg/kg every 12 hours by nasogastric tube)

  • Used in cases of intestinal or biliary obstruction

  • Can be used to paralyze the worms and help relieve obstruction

• Surgical removal is occasionally required