Symptoms of Crypto

Key points

  • Symptoms of cryptosporidiosis generally begin 2–10 days (average 7 days) after becoming infected with the parasite, Cryptosporidium (or "Crypto" for short).
  • The most common symptom of cryptosporidiosis is diarrhea lasting days to weeks.
Woman sitting on the couch holding her stomach in pain

Signs and symptoms

The most common symptom of cryptosporidiosis is prolonged, frequent, and watery diarrhea. Other symptoms include:

  • Stomach cramps or pain
  • Nausea
  • Vomiting
  • Fever
  • Weight loss
  • Dehydration

Crypto infections primarily affect the small intestine in the digestive tract. However, in people with weakened immune systems, Crypto infections can affect other areas of the digestive tract, such as the biliary tract or pancreas, or the respiratory tract.

People previously infected with Crypto can quickly make antibodies to fight off Crypto if infected again. When this happens, people who are reinfected have fewer or no symptoms.

When symptoms start and how long they last

Symptoms typically begin 2–10 days (average 7 days) after infection. Symptoms usually completely go away within 2–3 weeks (with a range of a few days to 4 or more weeks) in people with healthy immune systems. Symptoms can come and go for up to 30 days.

Severe symptoms

People with weakened immune systems who have severe cryptosporidiosis can develop chronic illness or even life-threatening problems with digesting or absorbing nutrients from food, as well as increasing weakness and loss of muscle (wasting). Examples of people with weakened immune systems include:

  • People infected with HIV
  • Cancer or transplant patients who take drugs that weaken the immune system
  • People with inherited diseases that affect the immune system

The risk of developing severe disease depends on how weakened the immune system is.