Friday Parasite #28: Big Honking Worms

Last night, Jim Cambias and I were at a party for Small Beer Press’s most excellent 2007 releases, and the conversation turned to our own summer release – Parasites Unleashed. The subject inspired John Crowley to tell us a parasite story (with frequent interjections from his wife Laurie that he was getting it all wrong) about a surgeon he knew who was working in Afghanistan. The surgeon had put the patient under a general anesthetic, set an oxygen mask on his face, and left the room when he heard the nurses start screaming. A huge honking roundworm had come crawling out of the guy’s nose.

“Ascaris lumbricoides!”  I cried.

Everyone was impressed, but they shouldn’t have been. A. lumbricoides is probably the most common parasitic worm found in humans. There are more than a billion infected people on the planet. That’s 1 in 6. Some estimates put the infection rates as high as a quarter of all humans.

Adults typically live in the small intestine, but immature worms are real wanderers. If a person has the misfortune of swallowing some Ascaris eggs, probably from food that’s been in contact with an infected person’s feces, he’ll soon have larval worms hatching in his stomach. The worms burrow through the intestinal wall, then ride through the bloodstream to settle in the lungs. After they grow a bit bigger, the young worms dig through the lungs and climb up the bronchi into the throat. Most of them get reswallowed. When they get back to the small intestine, they mature and start reproducing. The entire process takes two to three months. Adults get quite large – some females are more than a foot long. So if they leave the intestine to go a-wandering again, they can be rather shocking.

Comments

[Drhoz!]

ah, parasites, so very ingenious cool. People keep telling me I shouldn't be so enthusiastic about parasites, but I tell them dinosaurs are cool as well, but I wouldn't want one of them crawling out of my nose either.

[nai]

So how can one prove that they have one?

[DianeAKelly]

If you wanted to prove that you or someone you know is infected with Ascaris, your best bet is to check the suspect's stool for the worm's eggs.