The Bodacious Misery of Giardia

Her sickest patients had been to a petting zoo

Published: December 09, 2019
The isolation signs outside my hospital door. Photo by Phyllis DeGioia.

“No more drinking from the toilet!” my friend wrote in the get-well card.

The card was for me, not my dog.

She brought it with some chicken soup while I was recuperating from a severe case of giardiasis. Starting in the middle of September, I had that unhappy experience with the diarrhea free-for-all that comes from the parasite Giardia. That has a fecal-oral transmission, i.e., it usually comes from putting something in your mouth that's been contaminated with poop or drinking water that's flowed over poop. I had no idea diarrhea could be that violent, nor did I realize it could be the color of Shrek.

While sick for 6 weeks, I was significantly ill for 3.5 weeks. During those bad weeks, I went to the ER three times, was hospitalized for 3 days, and received approximately 14 liters of IV fluids to treat dehydration. The first course of antibiotics didn’t work, so then I took a different one; my doctor says it’s not unusual for that to happen. I will never make fun of adult diapers again. The only silver linings are that I lost 10 pounds and I didn’t run out of three weeks of accrued sick leave. I have about a day left at this point, but am not yet using vacation time.

People, dogs, and cats are the most common victims. My dog, however, did not have it, which is now in my medical chart in bold letters: Dog tested negative.

That’s not a big surprise, even though it was comforting to know. The Centers for Disease Control and Prevention (CDC) says, “The risk of humans acquiring Giardia infection from dogs or cats is small. The exact type of Giardia that infects humans is usually not the same type that infects dogs and cats.” That doesn’t mean it’s impossible, so when I felt awake enough to drive — with severe giardiasis, you are pretty much sleeping or sprinting to the toilet — I had my dog tested

There are eight recognized strains of Giardia. These strains are called assemblages just to confuse non-medical people <kidding>. Each of these strains generally only infect certain species, so the strain that dogs get doesn’t cross to a cat, and vice versa. Dogs tend to get strains C and D, cats get F, and people typically get A or B. Although infection with A and B is unusual in dogs and cats, it can happen and there are rare reports of transmission between people and dogs or cats. The zoonotic potential of giardiasis remains controversial. I don’t much care where I got it; I just desperately wanted to get rid of it.

Most dogs, cats and people – the three species most likely to get giardiasis – usually don’t know they have it. That’s scary because it’s easier to infect others that way. Some get “dire rears,” some don’t, and some get explosive diarrhea that dehydrates you into beef jerky. Infected infants of any species can end up with a failure to thrive and other unfortunate medical issues.

The health department called the day after I got out of the hospital, and we decided we would never figure out for sure where I got it. The first question every new nurse and doctor asked was if I had been out in the wilderness drinking untreated water because that is the most common way Americans contract it; that’s why it’s often called beaver fever. I had not been in the Great Outdoors. I had, however, been to a sheep and wool festival two days before I had symptoms. While there, I was eating popcorn (oral) and briefly touched the shiny, clean metal railing of an occupied sheep pen (fecal). I didn’t touch those darling sheep because I was eating. Duh!

As my go-to infectious disease guy, Dr. Scott Weese, says in his Worms and Germs blog

“At petting zoos, fecal contamination can be present anywhere on an animal’s body, or any other surface such as gates, walls, floors, troughs and other equipment. Bacteria or parasites can be present on an animal or a surface even if the fecal contamination is not readily visible…”

Dr. Weese also says that people don’t need to have direct contact with the animals at a petting zoo to get sick. Outbreaks of illness have occurred in people that only had contact with the petting zoo environment (e.g., gates, fences), so hand hygiene is important for everyone who enters a petting zoo area, not just the people who do the petting. Dr. Weese also mentions that food should not be allowed in the petting zoo area, and should certainly not be for sale there. Oops.

Sadly, the hand sanitizer that petting zoos provide does not protect well against Giardia. In my hospital room, where I was put in isolation, a sign on the sanitizer dispenser said not to use it and to wash your hands with soap and water. Everyone came in with a gown, gloves, face mask, and usually a cap; at least it wasn’t a hazmat suit.

What bothers me most is that I’m an OCD handwashing nutcase. I get what other people don’t. (I’m like a dog born in a puppy mill.) How do you prevent most of the icky stuff you can get in the world? Wash your hands with soap and water. Thus, the obsessive handwashing -- my hands are often dry because I wash them so often. You should see me cooking eggs, preparing raw meat, or skulking out of public bathrooms without touching anything. I repeat: Nutcase. How does giardiasis happen to a hand washing nutcase? Sheer bad luck, I suppose, or perhaps sheer stupidity on my part.

One of my nurses said that the sickest patients she’d ever seen had all been to a petting zoo. The stuff people can pick up there is hard core icky. Although E. coli, Cryptosporidium, and Salmonella infections are the most common, we humans can contract campylobacter, giardiasis, Q fever, and ringworm. Going through most of those is hell, and while ringworm is annoying, I’d take it any day over giardiasis.

Obviously, whenever people get some disease that is transmitted by the fecal-oral route, it’s by accident (at least I hope it is). It’s in soil, food, or water contaminated with feces. That’s why you are supposed to wash your produce before you eat it: it could have been grown in a field where water contaminated with all sorts of scary stuff was used.

Potentially, in people there are long-term consequences: they ain’t just whistling Dixie when they refer to recurrence, fatigue, post-infectious irritable bowel syndrome, etc. Apparently, I can anticipate sudden diarrhea any time over the next two years, and an upset stomach for up to 6 months afterwards, but so far just more fatigue.

And our pets?

Dogs and cats are treated with either fenbendazole, which is more effective on dogs than cats, or metronidazole, which seems to work better in cats than it does in dogs. Dogs and cats are rarely severely affected, therefore only occasionally need to be hospitalized for fluids, according to internist Dr. Sherri Wilson. Patients who are symptomatic are usually young, and many have come from a stressed, over-crowded shelter situation. When they are sick enough to hospitalize, the doctor typically looks for concurrent problems, like other parasites or parvovirus.

If the first drug used does not stop the diarrhea, then the veterinarian would try the other (e.g., fenbendazole if we had already used metronidazole, and vice versa). That doesn't happen often as either one is successful about 90% of the time.

More commonly, if the pet has received good drugs for Giardia and still has the organism but the diarrhea has resolved, Dr. Wilson says NOT to continue trying treatment after treatment. Just stop looking for the organism! If you’ve tried good drugs for Giardia and organisms are seen and the pet still has diarrhea, it's probably something besides the Giardia that is causing the diarrhea; again, don't keep trying more and more exotic drugs for it, but look for other parasites. If the diarrhea is chronic, look for inflammatory bowel disease

If you had it for a day, you would do anything not to have it for weeks because it sucks the quality right out of your life. I'd like to be able to say I'm not bitter, but the truth is that I’m totally bitter about the little terrorists having a party in my intestines.

Preventing giardiasis and its ilk is mostly common sense, which apparently I do not have:

  • Purify water in the wilderness before you or your dog drink it. 
  • Wash your hands often with soap and water after a petting zoo or the county fair, not just hand sanitizer.
  • Avoid getting your pet’s poop on your skin. If you do, wash your hands and any other affected areas in soap and water.
  • Bathe your pet with shampoo after treatment for Giardia, especially around their bottom.
  • If your carpet or furniture gets stained, clean and disinfect it. 
  • Anyone in your household with explosive diarrhea should see a doctor.

No one wants to experience the poop fest that is severe giardiasis. I wouldn’t wish it on anyone, except possibly a politician because they’re full of poop anyway.


March 28, 2022

I've heard they may not have any symptoms. My kitten who we found has it and is on Metronidazole. I read that it is more common in puppies and kittens not to always have symptoms.

Nancy Batista
December 3, 2021

Hi my puppy was just diagnosed with this but has never had even a loose bowel movement so what does this mean

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