This topic has been running through my mind quite a bit lately. Infectious diarrhea is one of the world's most vicious killers, but is susceptible to basic public health measures such as clean water and good sanitation, which is why cholera-ridden Americans aren't dropping dead in pools of their own feces. (Citizens of other countries aren't quite so lucky.)

There are many causes to this common problem---various bacteria, viruses, parasites, and a host of non-infectious causes. Even in here in the U.S., public health measures sometimes fail us, as seen in the ongoing Salmonella outbreak.

But diarrhea isn't just a load of crap. Let me explain.

First of all, what is "diarrhea"? The scientific definition is---for people on a "Western" diet---greater than 200g of stool in 24 hours. While this may be nice and standard, I don't usually ask my patients to collect and weigh their stool. A more useful operational definition is the more vague "increase in frequency and change in consistency (looser) of stool".

Most of us "know" if we have diarrhea, but in the office, I need to know. Someone who simply has had a few cramps and one extra bowel movement requires a different work up than someone with ten episodes of watery stool and a fever.

Some notable infectious diarrheas:

Norovirus: A common cause of "food poisoning", this is the infamous "cruise ship" virus. It is very, very contagious, and can be deposited on foods, surfaces, anywhere, really. Thankfully, the horrid symptoms don't last very long.

Salmonella: This lovely bacterium is infamously infectious---only a few individual bacteria need be ingested to cause illness. They usually cause "dysentery"---a bloody, crampy, feverish diarrhea. It can be found in eggs, meat, and, apparently, tomatoes.

Campylobacter: Now this bacteria is a real winner. It can cause inflammation throughout the whole bowel, often leading to "pseudo-appendicitis", that is, it is often associated with abdominal pain that mimics appendicitis and other abdominal diseases. To add to the fun, it is sometimes associated with Guillain-Barre syndrome, a paralytic disorder.

Pseudomembranous colitis: This is a really, really fun one. Clostridium difficile is a bacterium that lives in the gut. It can cause disease in anyone, but people who are given antibiotics often kill off more beneficial gut bacteria, leaving this one to take over the joint. It produces a toxin that makes you quite ill, with a fever, remarkably high white count, and sometimes (not frequently, thankfully), it can actually cause your colon to swell to the diameter of your leg. That's not good---you can tell by the name of the condition: "toxic megacolon". In hospitals, we try our best to prevent this, by avoiding unnecessary antibiotics, isolating infected patients, and washing our hands frequently. Unfortunately, this bacterium can form spores which are highly resistant to, well, everything.

Cholera: Vibrio cholerae is a fascinating organism that causes a devastating disease. It is passed from feces into water, and then ingested, so poor sanitation and poor water quality are the big problems here. It loves events like Cyclone Nargis. A toxin produced by the bacteria causes water to poor out of the gut by the gallon until the victim has literally shit themselves to death. It's hard to imagine a worse way to go (OK, maybe not that hard, but still...).

So why bother talking about diarrhea? Sure, there is a certain amount of guilty scatological pleasure (isn't there??), but really, why bother?

Because infectious diarrheal illnesses are preventable, and they sicken and kill millions every year. Did I mention that they're preventable?

Access to clean water, appropriate sewerage/latrines prevent most of these infections. Good medical care for those who still get ill saves lives.

But here in the industrialized, wealthy U.S., we still have deadly outbreaks of diarrheal illnesses. Enterotoxic E. coli infections, C. diff., Salmonella, cryptosporosis--- all of these have caused disease and death here at home. Much of this can be attributed to food contamination, health care-related infections, and in the case of cryptosporosis, contaminated water supplies---in other words, we should be able to do better.

Diarrhea is common, nasty and preventable, and no part of the world in unaffected. Let's do better.


More like this

What is the one I get from the cart handles at the grocery store?

I recently watched a TED talk by Paul Ewald on this subject. His focus was on what makes one strain more harmful than another, and what public health measures can actually drive the disease to evolve into a less harmful form. Quite interesting!


What? No Giardia lamblia?! How can you talk about infectious diarrhea and not talk about the protozoan with a name that sounds like a fraternity? Does salmonella make stools a nice pale icky color? No. Does C. diff. diarrhea have the delightful bouquet that one gets with Giardiasis? No. Does noro give its diarrhea that nice greasy sheen? No. And Giardia even has the added bonus of flatulence. It's the infectious diarrhea that comes with it's own fanfare. We're talking total package here.

Pledge G Lamb!

Algerine, my mother had giardia. I'm given to understand that the local vector for it is Castor canadensis, so the vernacular name for it where I live is "beaver fever." :) So not only does it sound like a frat, but it has a cool colloquial name!

By Interrobang (not verified) on 04 Jun 2008 #permalink

I'm currently working with Enterotoxigenic E. coli. It's not the most lethal, but it's the most commonly isolated enteropathogen, commonly spread through fecal contamination of water supplies. It's mostly fatal in developing nations, in children and elderly (immuno-naive) who can't afford antibiotics (and don't know about electrolyte and fluid replacement - and can't get clean water even if they do). I'm studying surface pili (CS1 pili) which are critical to ETEC infection, and a likely vaccine candidate, though the assembly mechanism hasn't been determined yet (I'm working on that one).

Another interesting fact about Vibrio cholera, is that it's associated with Copepods - zooplanktonic organisms. Epidemiologically, cholera outbreaks are often tied to planktonic blooms. By filtering the copepods from drinking water... even by a simple cloth over a drinking glass (for example) most of the copepods can be filtered, virtually ceasing chance of cholera infection. This, in turn, can keep fecal contamination of water supply from occurring.

I love articles like this.
Two questions: how do the organisms and their toxins cause diarrhea, that is, what is the mechanism? And do they all cause diarrhea as part of their life cycle the way cholera does?

One piece of possibly useless trivia concerns the Japanese word for diarrhea; it apparently sounds almost exactly like the english phrase "let it be" - a fact I wish I was informed of BEFORE I chose you that particular Beatles song in a Karaoke with my new Japanese in-laws.

I did leave out a number of other good ones. Giardia is always fun, and as someone who enjoys the outdoors, I'm a big fan.

All of the brands of E coli (EHEC, ETEC, etc) are fun, especially with hemolytic-uremic syndrome.

Really, I could post on diarrhea all week.

As to mechanisms, neveu, I'll see if I can throw together a post tonight---it's fascinating.

I highly recommend the book 'The Ghost Map' by Steven Johnson. It is the story of the Cholera epidemic in 1850's London and how John Snow solved the problem. What makes the book better than most other scientific books of its kind is it does a good job of putting the story into the context of the age and lives of the people involved.

Last week we all had Diarrhea at my house. On Sunday we were at a party with lots of family, where my toddler tried to go for a swim in the mucky pond. We also got there a little late, and ate BBQ pork sandwiches that were in metal pans over those little flame warmers.

My toddler got sick first, early Tuesday morning, with diarrhea and occasional vomiting but no other symptoms. Then my husband got sick early on Wednesday, and me very late that night. My illness lasted 12 hours, my husband's two days, and my son's for 8-9 days.

Seeing as our illnesses were so staggered, I have one peice of advice for everyone: wash your hands! My husband admitted that he wasn't washing his enough, especially with him chasing the kid around (he stays home while I work). That alone would probably have kept us from being as sick.

@ neveu - There are many types of diarrhea-causing agents, and they all have different mechanisms. Generally, though, they all cause some sort of fluid and electrolyte excretion in the intestinal tract, in order to 'steal' water and nutrients. It provides an excellent medium for growth.

ETEC, for example, is non-invasive. It doesn't directly infect host cells, but it binds to the walls of the intestine and injects a toxin that messes with cGMP or cAMP signaling. This indirectly results in fluid excretion.

Other types of bacteria are invasive. That's when you get bloody stool.

When my son (who graduates from high school Tuesday (I feel way too young to have an 18 year old son heading for college (sorry))) was about two years old, he had the most incredible bout of diarrhea (which, from the description (colour and odour) by Algerine may have been Giardia) while we were coming back from visiting relatives. Now, if he complains about having to do something, I cheerfully remind him that I have twice stopped alongside I-84 in Connecticut and New York to POUR OUT HIS BUCKET STYLE CAR SEAT!!!! The pale tan colour and truly atrocious acidic odour will be embedded in my gray cells forever. Recounting that incident usually shuts him up.

I always assumed that the diarrhea was a breeding strategy by the organism. If it lives in the gut, and needs to get into new guts, getting out in a, well, shall we say, sloppy? manner will increase the chance of infecting another unsuspecing GI tract. Of course, I majored in history, so if I'm wrong, please correct me.

Campylobacter made me miss 4 days of work during my 3rd week of a new job. Little bastards. I was sick for about 10 days in total.

You left out Rotaviruses. Thought to be the cause of roughly half a million infant deaths each year. Not so easy to get rid of with clean water, rotaviruses infect nearly every child in the USA and Europe before age 3. But easily treated with clean water and electrolytes. A vaccine is now being tested, but the rotaviruses are a diverse group, and I am not sure how many subtypes a single vaccine can cover.

Calling giardiasis "Beaver Fever" is a cute but probably inaccurate bit of hiker lore, according to the people who research these things. The beavers most likely get infected by contact with improperly disposed-of human waste. n their natural state, the beavers don't actually infect their own water supply.

Unlike humans.

I did field trips to Venezuela over several years. I soon learned to wait a week or so after I got back to Illinois before frequenting my local fast food burger joint. If I had a burger there the day after I got back I would have a mild case of diarrhea. If I waited a week, no problem. Very strange!

By Jim Thomerson (not verified) on 05 Jun 2008 #permalink

timely post, given that I was hospitalized on Monday night for dehydration due to vomiting & diarrhea - presumed to be a norovirus. Nothing like the nausea, vomiting & diarrhea trifecta to not only wreck a weekend in Montreal but to screw up your first week of a business trip in Halifax.

But the triage nurse at the Dartmouth General ER was AWESOME.

Finally manged solid food twice today. Yay.

By CanadianChick (not verified) on 05 Jun 2008 #permalink

CanadianChick, let's wait to elope until you're non-infectious :-)

I was hospitalized on Monday night for dehydration due to vomiting & diarrhea

Yep, that's a fun combination. Nothing like holding the trash can between your feet while you simultaneously...well, you know. Around our house we call it DAVE--the Diarrhea And Vomiting Epidemic.

Great list. Among the causes you left out: diarrhea is hereditary.

It runs in your jeans.

By Diarr Straits (not verified) on 08 Jun 2008 #permalink

We're on something like week 3 of 3-year-old diarrhea. Never bad enough to dehydrate him and he's eating and drinking fine, so all we can do is wait it out. I won't go into details but yuck. I'm guessing at this point bacterial rather than viral, but it doesn't seem to make a difference. Meanwhile baby sister (almost 1 year old) seems to have had it for a couple of days and got better. Don't know what to make of that. Of course, she may just have had some other virus with similar presentation. Why are we all feeling compelled to share these stories? I suppose to some degree it's because GI complaints are so universal.