Cryptosporidiosis: Symptoms, Causes, Treatment & Prevention

Cryptosporidiosis: Symptoms, Causes, Treatment & Prevention

Cryptosporidiosis is an illness you get from the parasite Cryptosporidium. It causes watery diarrhea that can be severe. You get cryptosporidiosis from contaminated water, like pools or lakes, or from other people. It can cause life-threatening complications. A Cryptosporidium infection can become chronic if you have a weakened immune system.

What is cryptosporidiosis?

Cryptosporidiosis is an illness you get from the parasite Cryptosporidium. It causes watery diarrhea and other gastrointestinal (gut) symptoms. You usually get it from contaminated water in public pools or other recreational swimming areas.

Cryptosporidiosis is also called crypto.

Who does cryptosporidiosis affect?

Children between 1 and 4 are the most likely to get cryptosporidiosis. It spreads easily in kids because they don’t yet have good hand washing habits or understand how germs spread. Infected poop in diapers also helps spread crypto among young kids and their parents.

You’re also at higher risk for getting cryptosporidiosis if you:

  • Are over 75.
  • Live or work with young children.
  • Drink unfiltered or untreated water (often while traveling, hiking or camping).
  • Work with animals, particularly farm animals or livestock.
  • Frequent public pools or reactional water areas (lakes or rivers).
  • Take care of someone who has cryptosporidiosis.

Who’s at risk for severe cryptosporidiosis?

If you’re living with a compromised immune system and get cryptosporidiosis, you’re at risk of ongoing and life-threatening illness. Half of all people living with AIDS will never get rid of Cryptosporidium once infected.

It’s important to take precautions to avoid infection with Cryptosporidium if you’re:

  • Living with HIV or AIDS.
  • Living with cancer.
  • A recent recipient of an organ or stem cell transplant.
  • On medications that suppresses your immune system.

Pregnant people and infants are at higher risk of dehydration from diarrhea.

How common is cryptosporidiosis?

It’s estimated that there are over 700,000 cases of cryptosporidiosis in the U.S. each year. Cryptosporidiosis is the second most common cause of diarrhea in children (after rotavirus).

Is Cryptosporidium serious?

Cryptosporidium infections usually aren’t serious for someone with a healthy immune system. If you have a compromised immune system, cryptosporidiosis can cause severe and long-lasting diarrhea, which can be life-threatening.

Symptoms and Causes

What are the signs and symptoms of cryptosporidiosis?

Symptoms of cryptosporidiosis start two to 10 days after you’re exposed to Cryptosporidium. Symptoms include:

  • Watery diarrhea (can be severe).
  • Stomach (abdominal) pain or cramping.
  • Nausea.
  • Vomiting.
  • Loss of appetite.
  • Low fever.

What causes crypto?

The parasite Cryptosporidium causes cryptosporidiosis. Cryptosporidium goes through your mouth into your digestive system, where it reproduces and causes symptoms.

Cryptosporidium is a protozoan parasite — a one-celled organism that lives off of animals and people. It’s so small that you can only see it with a microscope. Cryptosporidium hominis and Cryptosporidium parvum are the forms of crypto that usually infect people.

How do you get cryptosporidiosis?

Cryptosporidiosis is spread through the fecal-oral route, which means you get it from accidentally swallowing poop (feces) that has parasites in it. It’s very easy for cryptosporidiosis to spread from infected people or animals. You can get cryptosporidiosis from:

  • Contaminated water. This includes drinking untreated water and swallowing water from lakes, swimming pools, water parks or other recreational water areas. Chlorine doesn’t kill Cryptosporidium, and it causes most of the outbreaks of sickness from public pools. This is the most common way to get cryptosporidiosis.
  • Contaminated food. This includes unwashed fruits and vegetables, unpasteurized apple cider, unpasteurized milk and food made with unpasteurized milk.
  • Contaminated items and surfaces. This includes touching items and surfaces that someone with cryptosporidiosis has touched, caring for someone (including children) with cryptosporidiosis and changing diapers.
  • Infected animals. Touching animals at petting zoos and farm animals can spread cryptosporidiosis.
  • Sex with someone who has cryptosporidiosis. While it’s not a sexually transmitted infection, you can get cryptosporidiosis from touching someone else’s anus or the area around it with your mouth, hands, penis or other parts of your body.

What is the main cause of cryptosporidiosis?

There are lots of different ways to get cryptosporidiosis, but the main cause of infection is usually from drinking contaminated water or getting water in your mouth at a lake, pool or other public swimming area.

Is cryptosporidiosis contagious?

Yes, cryptosporidiosis is contagious — it can spread from person to person, although indirectly. If you have cryptosporidiosis and don’t wash your hands after going to the bathroom, you can spread the parasite to anything you touch. If you go swimming while you have diarrhea, the parasite can contaminate the water.

If someone else touches a surface you’ve contaminated or gets water in their mouth that you’ve swum in, they can get sick too.

Diagnosis and Tests

How is cryptosporidiosis diagnosed?

Cryptosporidiosis is diagnosed with a stool (poop) sample. Your provider will give you a sterile container and instructions on how to get a sample. There may be a lot of parasites in your poop one day but hardly any on another day, so you may have to give samples over several days to get a diagnosis.

Your provider will also do a physical exam and ask about your symptoms and health history.

Management and Treatment

How is cryptosporidiosis treated?

Most people with healthy immune systems will get better without treatment for cryptosporidiosis. The most important treatment is drinking plenty of fluids to keep hydrated. Your provider may prescribe oral or IV hydration or antidiarrheal medications.

Antiprotozoal medication can also be used to treat cryptosporidiosis in people with healthy immune systems. Antiprotozoal medications stop protozoa like Cryptosporidium from growing in your body.

If you have an underlying condition that weakens you immune system, your provider will help you manage your underlying condition, which can help the symptoms of cryptosporidiosis.

What can’t I eat/drink with cryptosporidiosis?

If you have cryptosporidiosis, avoid eating or drinking anything that makes diarrhea and dehydration worse, like alcohol and caffeine. Some evidence suggests that avoiding foods with lactose (like dairy products) can shorten the amount of time diarrhea lasts. Ask your provider what foods you should eat and which to avoid.

What medications/treatments are used for cryptosporidiosis?

Depending on the severity of your symptoms and whether you have underlying conditions, your provider may prescribe:

  • Antiprotozoal medication. Nitazoxanide (Alinia®) might shorten the amount of time you’re sick with cryptosporidiosis. Nitazoxanide might not work as well if you have a weakened immune system.
  • Antidiarrheal medications. Your provider might prescribe medications like diphenoxylate-atropine (Lomotil®) or loperamide (Imodium®) to help stop the diarrhea. This helps prevent dehydration and losing important minerals from your body.
  • Hydration. Your provider might give you special fluids to rehydrate you and replace electrolytes (minerals that keep your body working properly).

Side effects of treatment

Loperamide can cause heart rhythm problems in high doses. Make sure you tell your provider if you have a heart or liver condition before taking this medicine.

Tell your provider if you have liver or kidney disease, bile or gallbladder problems or a weakened immune system before taking nitazoxanide.

How do I take care of myself/manage the symptoms of cryptosporidiosis?

The best way to take care of yourself at home with cryptosporidiosis is to make sure you’re staying hydrated and that your symptoms don’t worsen.

  • Drink plenty of fluids. Water, broth, sports drinks or oral rehydration solutions (like Pedialyte®) are the best choices to keep you hydrated.
  • Over-the-counter medications like loperamide (Imodium®) and bismuth subsalicylate (Pepto-Bismol®, Kaopectate®) can help stop diarrhea, but check with your healthcare provider before taking them. Don’t give medications to your infant or child without asking their pediatrician first.
  • Keep an eye on your symptoms. If you can’t keep anything down or your diarrhea is severe (more than 10 watery stools a day), contact your healthcare provider. You may need IV fluids or nutrition.

How soon after treatment will I feel better?

If you’re prescribed antiprotozoal medication for cryptosporidiosis, it can take five days or more to start feeling better. Take all of your medication as prescribed, even if you feel better before you’ve finished it.


How can I reduce my risk of cryptosporidiosis?

Cryptosporidiosis spreads easily. Alcohol-based hand sanitizers and chlorine in pools don’t kill Cryptosporidium. Being cautious in places where Cryptosporidium is found and practicing good handwashing and food prep habits are the best ways to reduce your risk of cryptosporidiosis. If you have a compromised immune system, it’s best to avoid public swimming areas and recreational water areas.

Ways to reduce your risk of getting and spreading cryptosporidiosis include:

  • Don’t swim if you have diarrhea. Wait at least two weeks after diarrhea goes away to swim.
  • Avoid getting water in your mouth if you swim in lakes, rivers or public pools.
  • Don’t drink untreated water or unpasteurized milk.
  • Wash, peel or cook fruits and vegetables before eating.
  • If you’ve been around farm animals or at a petting zoo, wash your hands thoroughly before touching your face or eating.
  • Teach children good hand washing hygiene at a young age.
  • Make sure kids wash their hands after touching animals and going to the bathroom.
  • Use a condom or dental dam every time you have sex. Wait two weeks after symptoms go away before having sex again.

Outlook / Prognosis

What can I expect if I have cryptosporidiosis?

For most people, cryptosporidiosis is self-limiting, meaning it will go away on its own. Because of the parasite’s life cycle, your symptoms may go away and then come back.

You may be contagious up to two weeks after your symptoms stop, so make sure you continue to take precautions even after you feel better. Don’t swim in public pools or have sex for two weeks after having diarrhea.

How long does crypto last?

If you have a healthy immune system, cryptosporidiosis usually goes away on its own in about two weeks. Some people have symptoms that come and go for 30 days or more. If you have a weakened (compromised) immune system, you can have symptoms for months or years.

When can I go back to work/school?

Since you can still spread cryptosporidiosis even once your symptoms are gone, ask your employer or school when you or your child can come back.

Complications of cryptosporidiosis

Cryptosporidiosis can make it hard to stay hydrated, especially for infants and pregnant people. Losing a lot of fluid can lead to serious complications, including:

  • Severe dehydration.
  • Electrolyte imbalance, which can cause problems with your heart and other organs.
  • Hypovolemia (loss of fluid volume in your body).

Bile duct, gallbladder or pancreatic disease are also complications of cryptosporidiosis. Some children have growth problems after having cryptosporidiosis.

Can cryptosporidiosis be cured?

In most people, your immune system will fight off Cryptosporidium and the symptoms of cryptosporidiosis will go away. Medications may also help cure a Cryptosporidium infection. In someone with a compromised immune system, cryptosporidiosis may never be fully cured and can cause symptoms for years.

Living With

How do I take care of myself with cryptosporidiosis?

Make sure you stay hydrated and try to get whatever nutrition you can while you’re sick. Severe diarrhea can lead to life-threatening complications.

Drinking lots of fluid like broth, water, sports drinks or oral rehydration solutions can help replace the fluid you’ve lost and prevent life-threatening electrolyte problems. Don’t drink caffeinated beverages or alcohol. Eat small bites of food if you’re able to.

When should I see my healthcare provider for cryptosporidiosis?

Contact your healthcare provider if you have symptoms of cryptosporidiosis, especially if you have large amounts of watery diarrhea (several episodes per day). If you have a compromised immune system, see your healthcare provider right away if you have any symptoms of infectious disease.

When should I go to the ER?

Go to the nearest ER if you can’t keep any food or liquid down, have more than 10 episodes of watery diarrhea in a day or have symptoms of severe dehydration, including:

  • Confusion.
  • Weakness or light-headedness.
  • Feeling dizzy when you stand.
  • Not peeing or barely peeing.
  • Dark-colored pee (urine).

What questions should I ask my doctor?

  • How can I manage my symptoms at home?
  • What medications can I take for my symptoms?
  • What should I eat or drink? What should I avoid?
  • What’s the best way to keep hydrated?
  • What should I do if my symptoms get worse or change?
  • What symptoms should prompt me to call you or go to the ER?
  • How can I avoid spreading cryptosporidiosis?


Most read