Written by:Fact check:

Overview

What Is Cryptosporidiosis?

Cryptosporidiosis is an intestinal infection caused by microscopic parasites called Cryptosporidium. The parasites can affect the lining of the intestine and commonly cause watery diarrhea, stomach cramps and other digestive symptoms. People often become infected after swallowing contaminated water, food or material from an infected person or animal. Illness may be more severe or last longer in infants, older adults and people with weakened immune systems.

Symptoms

Symptoms of Cryptosporidiosis

Symptoms commonly begin several days after infection, although the timing can vary. Some people infected with Cryptosporidium have no symptoms and may still spread the parasite. Diarrhea is often the main symptom and may continue longer in people with weakened immune systems. In the disease cryptosporidiosis, fluid loss is especially concerning for young children, older adults and people who cannot drink enough.

  • Watery diarrhea.
  • Stomach cramps or abdominal pain.
  • Nausea.
  • Vomiting.
  • Fever.
  • Dehydration symptoms such as unusual thirst, dry mouth, or reduced urination.

How It Spreads

How Cryptosporidiosis Spreads

Infection occurs when someone swallows Cryptosporidium oocysts, the parasite’s hardy infectious form, which are shed in infected stool. Spread can occur through contaminated drinking or recreational water, food, hands, objects and close contact with an infected person or animal. The parasite can move from contaminated material to the mouth when handwashing or other hygiene is inadequate.

  • Swallowing contaminated recreational or drinking water.
  • Eating food contaminated during preparation or handling.
  • Touching contaminated surfaces and then touching the mouth.
  • Having close contact with an infected person or animal.
  • Caring for young children or people with diarrhea without careful hand hygiene.

Important prevention point

Water can spread Crypto

Cryptosporidium can survive in treated recreational water. Anyone with diarrhea should avoid swimming and follow local public-health guidance about when it is safe to return after symptoms stop.

Risk Factors

Risk Factors for Cryptosporidiosis

Risk of exposure and risk of severe disease are not the same. Recreational water, childcare, travel and animal contact can increase the chance of infection, while weakened immunity mainly increases the risk that illness will be prolonged or severe. Some exposure-related risks can be reduced through hygiene and water safety, but medical conditions and immune status may not be fully controllable.

  • Swimming in pools, water parks, lakes, or other recreational water.
  • Living with or caring for someone who has diarrhea.
  • Working in childcare, healthcare, or other settings with frequent close contact.
  • Traveling to places where drinking-water treatment and sanitation are limited.
  • Having contact with infected animals or their environments.
  • Having a weakened immune system, which can increase the risk of prolonged or severe illness.

Complications

Complications of Cryptosporidiosis

  • Dehydration can develop when ongoing diarrhea and vomiting cause excessive fluid loss.
  • Electrolyte disturbances can occur with significant or prolonged diarrhea.
  • Weight loss and malnutrition may develop when illness continues for a long time.
  • Persistent infection can cause prolonged diarrhea in people with weakened immune systems.
  • Severe illness can be dangerous for people with advanced immune suppression.

Seek prompt care

Watch for dehydration

Inability to keep fluids down, very little urination, confusion, fainting or signs of severe dehydration require prompt medical assessment.

Diagnosis

How Cryptosporidiosis Is Diagnosed

A clinician may ask about the duration of diarrhea, recent travel, drinking or recreational water exposure, sick contacts, animal contact and immune status. These details help determine whether cryptosporidiosis is likely and whether another cause of diarrhea should be considered. Diagnosis usually requires laboratory testing of a stool sample.

  • A stool sample is tested for Cryptosporidium proteins or genetic material.
  • Microscopy with specialized staining may be used to look for the parasite.
  • Additional stool samples may be needed because the parasite is not shed consistently.
  • Clinicians may order additional tests when symptoms suggest another infection or complication.

Treatment & Management

Treatment and Management of Cryptosporidiosis

Many otherwise healthy people recover from cryptosporidiosis with fluids and supportive care. Treatment decisions depend on symptom severity, how long symptoms have lasted, age and immune status. People with ongoing diarrhea or a weakened immune system may need closer medical follow-up.

  • Use oral rehydration fluids to replace water and electrolytes lost through diarrhea.
  • Seek medical treatment for severe dehydration or inability to drink enough fluids.
  • A clinician may prescribe nitazoxanide for some people, depending on age and immune status.
  • People with weakened immunity may need evaluation and management of the underlying condition to help control persistent infection.
  • Do not start anti-diarrheal medicines in children or people with severe illness without medical advice.

Prevention

How to Prevent Cryptosporidiosis

  • Wash hands with soap and water after using the toilet, changing diapers, caring for someone with diarrhea, and before preparing or eating food.
  • Avoid swallowing water from pools, water parks, lakes, rivers, and other recreational sources.
  • Do not swim while experiencing diarrhea and follow public-health guidance before returning to the water.
  • Use safe drinking water and take extra precautions with untreated water while traveling.
  • Wash produce and prevent cross-contamination during food preparation.
  • Avoid preparing food for others while sick and for the recommended period after diarrhea stops.

Practical tip

Soap and water matter

Alcohol-based hand sanitizer does not reliably replace washing with soap and water for preventing the spread of Cryptosporidium.

Outlook and Prognosis

Outlook and Prognosis

Cryptosporidiosis is often self-limited in otherwise healthy people, meaning it improves without long-term illness. Symptoms can persist or become severe in infants, older adults and people with weakened immune systems. Prompt attention to hydration and medical review of persistent symptoms can help reduce complications.

Factors that can affect recovery time

  • Adequate fluid replacement supports recovery and helps prevent complications.
  • Young children and older adults may become dehydrated more quickly.
  • Weakened immunity can lead to longer-lasting or more severe infection.
  • Continued exposure can contribute to reinfection or further spread.
  • Persistent symptoms or signs of dehydration should prompt medical review.

When Should You See a Doctor

When Should You See a Doctor?

  • Contact a clinician for diarrhea that is severe, persistent, or repeatedly returning.
  • Seek medical advice promptly if the person is an infant, older adult, pregnant, or immunocompromised.
  • Ask for care if vomiting prevents drinking enough fluids.
  • Get urgent help for confusion, fainting, severe weakness, or very little urination.
  • Contact a clinician after a likely exposure if symptoms develop or if another cause of diarrhea is possible.

Branches

2 topics

Symptoms

5 topics