*Necator americanus* (Hookworm) and latrines.

Long ago, people in the Southern United States would just go #2 by going out to a field and squatting. The problem is that there are parasites, namely hookworm, that can crawl out of old poo and reinfect people. While a few hookworms aren't that bad, *too* many can cause severe lethargy.

Enter the solution: a pit latrine. Dig a hole deep enough so the hookworms can't find another foot to invade before they die, and problem solved.


References

* [How a Worm Gave the South a Bad Name](http://www.pbs.org/wgbh/nova/next/nature/how-a-worm-gave-the-south-a-bad-name/)
* [How the Outhouse Helped Save the South](http://endtheneglect.org/2012/01/how-the-outhouse-helped-save-the-south-and-what-it-can-do-for-the-worlds-bottom-billion/)