Thoughts on pinworm infections…

I had a strongly worded email from someone who had apparently read, and taken exception to, one of my articles about pinworm (Enterobius vermicularis). I think it was probably this one: “Pinworm – A Common Intestinal Worm in Children,” though s/he didn’t specifically say. I was a little surprised by the tone of the email – who knows why someone would become attached to this particular soapbox – but the vehement claim that the human immune system will eradicate a case of pinworm (enterobiasis) got me thinking.

Pinworm life cycle CDC (Public Domain)

I’m of the understanding that a pinworm infection will resolve on its own eventually if left untreated – and I never said otherwise – but what role does the immune system play? Can the immune system kill the adult worms? We know that the immune system responds to parasites, but many parasites are good at evading immune attacks, and prompting moderation of the immune response. Enterobius vermicularis should be particularly good at this because it is one of our heirloom parasites: it’s been with us hundreds of thousands of years.

Add to this the frequently reported problem of reinfestation through swallowing eggs in the home/school environment and one begins to suspect that waiting for the immune system to do the job could be a long process. It’s clear that, for many people, the immune system is ineffective at eliminating the adults (they likely die of old age after a month or so), and unable to effectively kill larvae over the long term after initial exposure.

Having said all that, it probably doesn’t matter all that much, except for those unfortunate hosts that experience bad symptoms.

Final thoughts on this:

• Texts tell us that the majority of pinworm infections are asymptomatic, so lots of people have pinworms, don’t suffer any unpleasant symptoms, and eventually eliminate the worms on their own. (And if they have no symptoms, they’re less likely to spread it around.)
• The ability to fight off enterobiasis likely varies from one person to the next, as it appears to with other parasitic worm infestations.
• An overzealous approach to eradicating pinworms is probably unrealistic.  They’re so good at spreading themselves around, and we’re so poor at fighting them off, that actually getting rid of them is next to impossible.
• When symptoms are severe and persistent, only the most stoic of patients would refuse treatment. I’ve never had the pleasure myself, but I’ve heard first hand accounts that were not pretty.