La Navidad Mexicana, Part 1. Or, When You're Sliding Into First...

Every Christmas holiday, the members of my family uproot from their various corners of the continental U.S. and converge on an area of the Greater Northern Detroit suburbs known as Lake Orion, where our parents have lived for the past ten years. Michigan is, in general, a flat state, and Lake Orion is characterized by a distinctly two-dimensional element—an element amplified by the single, white, depthless cloud that covers the sky like a non-retractable dome for the majority of the wintertime. The only notable topography in the area is a giant landfill by the highway, across from a sign that reads “Lake Orion: Where Living is a Vacation.”

And then there’s the weather. In Michigan, in late December, there are always variables—it may or may not be snowing, it may or may not be windy—but it is always cold. Really, really cold.

Regardless of the fact that we always have an excellent time in Michigan over Christmas, the family decided this year to try for a spot where living might actually feel like a vacation. And so, instead of blustery Michigan, we met up in Akumal, Mexico for a week of sunshine, relaxation, and fun—and a little diarrhea.

Everyone in the family is pretty private about these kinds of things, so I don’t really know exactly who got it and exactly how bad it was, but I know it made, at least, a brief pass through the villa.

Which made me wonder: Why are people always getting sick when they go to Mexico? Why aren’t we supposed to drink the water? What’s in the water there that makes so many visitors to the area sick? And why aren’t the native Mexicans sick? And what is diarrhea, anyway?

In Mexico, Traveler’s Diarrhea goes by the less formal name “Montezuma’s Revenge.” The name comes from the Aztec king Moctezuma whose empire fell to the Spanish in the mid-16th century (historical details are foggy, but what’s clear is that Moctezuma welcomed the Spanish explorer Hernan Cortes into his capital city of Tenochtitlan and ultimately got totally screwed by him. Sound like a familiar story?). The idea is that old Moctezuma is taking revenge on subsequent interlopers by afflicting them with vigorous bouts of nausea, cramping, vomiting, and diarrhea.

There’s also a more scientific explanation.

Traveler’s Diarrhea affects about 40% of people who visit Mexico, and is prevalent in many other underdeveloped nations around the world. While there are several bugs (parasites, bacteria, and viruses) responsible for TD, the most common culprit is a strain of e. coli referred to as enterotoxogenic e. coli, or ETEC. While it shares a proclivity for causing diarrhea with its notorious relative O157:H7, ETEC is not a deadly strain of e. coli. The good news is that most strains of e. coli are completely harmless (many take up permanent residence in our colons); the bad news is that where there is e. coli, there is poop. Which means that-- even if you don’t like to think about it-- there’s a little bit of fecal matter in the water in Mexico. (We’ll get into why that is later).

In order to understand how ETEC causes diarrhea, let’s make like an e. coli-tinged ice cube and take a hurried trip through the human GI tract:

Food begins to break down in our mouths, with the physical work of chewing and the chemical work of enzyme-laden saliva. The saliva also makes the food wet and mushy, so that it slides with relative ease* down the esophagus and into the stomach, where it hangs out for several hours. Here, gastric acid breaks the food down into a gooey, milky substance called chyme. This acidic environment also serves to kill off a number of potentially harmful bacteria.

From the stomach, the chyme makes its way into the small intestine by way of the pyloric sphincter. The small intestine is a hotbed of digestive activity where food gets broken down by a rich cocktail of bile, pancreatic juice, and digestive enzymes. The folded walls of the small intestine are covered in millions of little projections (think of a trimmed Koosh ball) that increase the surface area of the organ and allow for increased absorption of nutrients (converted glucose, fats, and amino acids). Excess liquids are also absorbed through the walls of the small intestine.

After the small intestine, food makes its last stop at the large intestine, or colon. Thanks to trillions of bacteria, this is where poop really becomes poop. The bacteria creates gas, turns the waste brown, and makes it smell like—well, shit. The colon is also theoretically where fecal matter becomes solid, due to absorption of liquid through the walls of the large intestine…

But here we need to take a step back and remember that we’re talking about diarrhea rather than semi-solid, healthy, normal feces. If the enterotoxogenic e. coli in your margarita’s ice cubes survives the gastric juices of the stomach and makes it to the large intestines, it produces a toxin that prevents the absorption of liquids and instead stimulates the opposite process. Instead of sucking moisture out of your poop, the walls of your large intestines let water in.

You know the rest of the story.

*The motion of food through the entire digestive system is aided by the action of peristalsis—the contraction and relaxation of muscles in the organ’s walls. Think of squeezing a tube of toothpaste or, perhaps more accurately, squeezing raw sausage out of it’s intestinal casing. If you’ve ever felt the urge to go to the bathroom right when you start eating, it’s because this action in the esophagus triggers a wave of peristalsis throughout the whole GI tract—all the way to the colon.

Pictures:
Digestive System
Michigan Winter
Akumal
E. Coli
Chyme

References:
The CDC
The Way We Work, David Macaulay
Textbook of Bacteriology