How to Treat Intestinal Parasites

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This survival-medicine website provides general information, not individual advice. Most scenarios assume the victim cannot get expert medical help. Please see the disclaimer.

The Parasitic GI Blues

by James Hubbard, M.D., M.P.H.

I thought it might be fun to occasionally share email questions I get from you, my readers. Please let me know whether these types of topics interest you, and feel free to send me your own questions on general topics. I may use the question (a full or edited version), your first name and your state in a future post.

Here’s the first one.

Dr. Hubbard:

I have a topic I’ve never seen addressed by an MD in the preparedness community, and one I’d like to hear a doctor’s opinion on.

I’m interested in learning more about what types of intestinal parasitic infections may be common in travelers/wanderers/refugees during a lengthy emergency. Specifically, in people that may have been sheltering in close quarters in less than sanitary conditions (like the Louisiana Superdome during Katrina), had eaten spoiled/ill-prepared food (from garbage cans/dumpsters, or undercooked meat/fish), or drank from non-potable water sources (lakes, streams, puddles).

Any advice on correctly diagnosing and stocking a medicine cabinet to handle situation like this? Simple faecal tests a layman might be able perform at home with some modest equipment?

The only antiparasitics we currently have are permethrin 5% cream and flagyl. Thinking it may be prudent to add praziquantel, mebendazole, and/or albendazole.


Enlarged picture of a giardia parasite.

If you have giardia, this is what you'll see moving across a slide under a microscope. Giardia is an infection of intestinal parasites you can get from drinking water contaminated with feces. See the sucking disk? That's what the parasite uses to attach to your intestine's cells.

It’s bad enough to get intestinal parasites if you have access to expert treatment. If you can’t get to a doctor within a few days, some of these infections can not just be miserable but deadly.

You mention three scenarios. Here’s a brief look at each:

  • Living with a bunch of people in unsanitary conditions: Intestinal parasitic infections are mostly spread through the fecal-oral route. That means shaking hands with someone infected who didn’t wash their hands thoroughly after wiping from a bowel movement. You then touch your mouth before you wash your own hands. Yeah, I know, yuck. But it happens all the time.
  • Eating spoiled or undercooked food: You can a get few intestinal parasites from this. Tapeworms would be hard to diagnose from clinical symptoms alone. Eating undercooked pork could cause trichinosis. But it’s bacteria that usually causes the diarrhea problems.
  • Drinking water that hasn’t been purified: Drinking water contaminated with feces is a biggie. Even most clear mountain water here in the United States is contaminated with giardia from animal feces.

Signs and Symptoms of Intestinal Parasites


Diarrhea Differences


  • Diarrhea from viruses usually spreads through close company like wildfire. There’s also vomiting. Symptoms don’t last much longer than twenty-four hours.
  • Diarrhea from bacteria, like e. coli, is usually accompanied by vomiting and happens to people who ate that specific contaminated something.
  • Intestinal parasites cause mostly profuse diarrhea, most often from contaminated drinking water.


Some intestinal parasites, like pinworms, mostly cause rectal itching. Others, like tapeworms, can cause nutritional deficiencies.  With some, like giardia, you have abdominal cramping, diarrhea, and severe dehydration.

You can diagnose most intestinal parasites with a microscope on low-grade magnification by putting a stool specimen on a slide and looking for the eggs. Sometimes you can actually see the worms in the feces. Of course, you need to know what you’re looking for—and plenty of disposable gloves.

In a setting without a microscope, you have to go on history and symptoms.

How to Treat Intestinal Parasites When You Can’t Get to a Doctor

Your list of meds sounds fine. Flagyl (metronidazole) might be the most important—at least the most used. Read the instructions, and don’t drink alcohol within twenty-four hours. It can cause violent vomiting. Mebendazole would treat giardia. The permethrin you mentioned would be more for external infections, like lice, mites, etc.

Dehydration is going to be the biggest acute concern. Stay on clear liquids like broth and water. Electrolyte drinks like Pedialyte are fantastic. Gatorade is an alternative. You can make your own by mixing a half-teaspoon of salt in a quart of water. Add a teaspoon or two of honey, molasses, or sugar if you have it.

The best lay book I know for makeshift rehydration fluids and diagnosing and treating parasites is Where There is No Doctor, by David Werner.

Of course, the best treatment for intestinal parasites is prevention. Don’t drink water that hasn’t been disinfected. Wash your hands. Wear Gloves. Properly dispose of fecal waste.

Thanks for the questions.

Photo courtesy CDC/Dr. Mae Melvin.

  • Guindilla Jason

    does it just mean good bacteria has also been eliminated and I should take probiotics

    • James Hubbard, MD, MPH

      Sounds like a good idea to me.

  • Guindilla Jason

    I have taken the medicine and feel better, but now my stomache hurts and is bloaty and weak. I feel the need to eat all the time like everything is striped out of it…

  • Bryan

    my english.bulldog has worms. as do i. visible in our poop and my skin. spraying house heavily with permethrin and eating probiotics. still losing the battle. please help with over the counter and home remedies as well as rx. what do i do?

    • Anonymous

      Actually, look at the Dr. Oz website, there’s a brief discussion on parasites. A man came on & purposely swallowed a tape worm, then tracked his symptoms…one of them was worms visible in skin.

    • James Hubbard, MD, MPH

      Bryan, I don’t know of any worms that would be visible in your skin. Sounds like you should see a doctor.

      • Kat Grrl

        A wolf worm would be visible. Though I’ve only personally seen them in cats.

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  • Dee

    I am a 37 yr old female. I have had nausea, fatigue, pain in my stomach, abdomen, uterine, sides, chest area. I am weak, shaky, not hungry, dizzy, bloated, and have had abnormal bowel movements (either diarrhea, constipation, or a combination) for a month and a half. I go to the doctor tonight. I inspected my stool today and found black, red/brown, and clear looking wormlike structures all in my stool. A week ago a urine sample revealed trace amounts of blood in my urine but nothing else. I had given a urine sample because there were black and redish tiny worm/hairlike structures that came out when I voided. Do intestinal parasites travel throughout the body? Should I ask my regular family doctor to do any certain thing? Any advice?

    • James Hubbard, MD, MPH

      I’m sure if you tell you doctor what you’ve told me, he/she will know what to do. I know of no parasite that travels through the intestine, bladder, and, say, the blood stream. Many types can certainly make you feel bad in various ways. Pinworms can get in the intestine and, rarely in the bladder, but pinworms usually don’t cause diarrhea. Please let me know what you find out.

      • punkinhoot

        There is a parasite quite common in Egypt that lives in the bladder and spreads eggs thru urine, frequently tainted red with blood. Sorry, don’t remember the latin name for it, I just remember that one should avoid swimming in the Nile.

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    Do you have any information on Non-Motor Symptoms of Parkinson´s Disease. In particular pain, fatigue and weakness of extremities.

    Thank you!

  • EX121

    If it’s giradia don’t forget the horrible stench as a diagnostic tool. speaking from experience, flagyl worls.

    • James Hubbard, M.D., M.P.H.

      Thanks for the first hand account. Experience is a great teacher.

  • James Hubbard, M.D., M.P.H.

    Thanks, Joyce.