Infectious Disease Compendium



A round worm. Ascaris lumbricoides (humans) and A. suum (pigs). Probably the same species in different hosts (PubMed). Pigs and humans are a lot alike. My wife would say men and pigs are identical.

They can be quite large: 15-30 cm long and 3-6 mm thick.

Epidemiologic Risks

Fecal-oral. Humans crap in the soil, you eat the soil, the worm goes along for the ride. Myocardial infarction be damned, that's why I only eat deep fried food. In Cornwall (England) A. suum has been spread from pigs (its normal host) to cause human disease.

The female makes 200,000 eggs per day for a year. The eggs are infectious after two weeks in soil and can persist in soil for 10 years.

At least 1 billion people are infected worldwide. That's a shi....never mind.

Pig farmers also spread the disease in the US, with cross-transmission between humans and pigs (PubMed).

And it was a problem, along with whip worm, for Crusaders (PubMed) and Richard III (Pubmed). Nothing like spending your time in Medieval latrines.

The oldest eggs found are 24,000 years old.


Mostly asymptomatic, can cause bloating and malnurition in the GI tract.

Löffler's syndrome: cough, transient pulmonary infiltrates and eosinophilia.

Occasionally they will be found clogging up the biliary system (I was called by a surprised surgeon once), pancreatic duct or causing small bowel obstruction if a huge worm load.

Everyone once and a while someone will pass a worm and freak, although more often than not I see a garden worm that somehow went from garden to pants to toilet.

Sometimes they can seen seen on barium contrast studies or on CT. Ew.

Look for O&P in stool or lung as symptoms suggest.


Mebendazole 100 mg bid x 3 days. Pyrantel pamoate 11 mg/kg orally (maximum of 1 g) is an alternative. In intestinal or biliary obstruction, piperazine, 150 mg/kg initially, followed by six doses of 65 mg/kg q 12-h to paralyze the worm and they pass on through. Ick.