Cryptosporidiosis: Advice for Immunocompromised People

What is cryptosporidiosis?
Cryptosporidiosis is a disease caused by a parasite (Cryptosporidium) found in humans, many animals, birds and fish. The parasite multiplies in the gastrointestinal tract of the host and tiny oocysts are excreted in very large numbers in the faeces. The parasite can cause a diarrhoeal illness in humans known as cryptosporidiosis.

What are the symptoms of cryptosporidiosis?
Symptoms include watery diarrhoea, stomach cramps, upset stomach and a mild fever. Some people have no symptoms.  Symptoms can appear 2 to 10 days after a person becomes infected. Symptoms usually last about 2 weeks however, you may continue to pass the parasite in your faeces (bowel motion) for up to 2 months. Symptoms may be more severe if you have a weakened immune system.

How does cryptosporidiosis affect you if your immune system is severely weakened?
In people with AIDS, and in others whose immune system is weakened, cryptosporidiosis can be a serious and long-lasting infection. If you have HIV infection and your CD4 cell count is below 200, Cryptosporidia can cause severe watery diarrhoea for a long time. If your CD4 cell count is over 200, your illness may only last for 2 weeks however, you may still carry the parasite and pass it on to others.

How is cryptosporidiosis spread?

• By accidentally swallowing anything that has come in contact with the faeces of a person or animal with cryptosporidiosis.
• By swallowing water contaminated with Cryptosporidium oocysts. This can occur if water from a swimming pool, jacuzzi, lakes, rivers and ponds are contaminated with sewage or faeces from infected humans or animals.
• By eating uncooked contaminated foods.

How is an infection diagnosed?
Your doctor will ask you to submit one or more faeces samples to see if you are infected. 

Can cryptosporidiosis be treated?
Most people with a healthy immune system will recover themselves. However, people with weakened immune systems are at greater risk of a more severe illness. There is no drug available at present to cure this infection. Some drugs, such as paromomycin, may reduce the symptoms of cryptosporidiosis. If you have diarrhoea, drink plenty of fluids to prevent dehydration. Anti-diarrhoeal medications may help slow the diarrhoea however, these should only be taken after consulting with your doctor.

How can I protect myself from cryptosporidiosis?
These following actions can help to protect you from getting cryptosporidiosis:

• Wash your hands. This is probably the single most important step you can take to prevent cryptosporidiosis. Always wash your hands before eating and preparing food, after using the toilet, after changing nappies, after gardening, and after touching pets or farm animals.
• Boil water. During outbreaks in your community water supply, boil drinking water for 1 minute to kill the parasite to make the water safe to drink.
• Avoid touching farm animals. Cryptosporidiosis is common in young animals, especially calves and lambs. Always wash your hands well with soap and water following contact.
• Avoid touching the faeces of pets. Most pets are safe to own. The risk of getting cryptosporidiosis is greatest from pets that are less than 6 months old or stray animals. If you must clean up after a pet, use disposable gloves and wash your hands afterwards. If any pet gets diarrhoea, have it tested for Cryptosporidiosis.
• Be careful when swimming in lakes, rivers, ocean water and swimming pools. Avoid swallowing water while swimming.
• Wash and cook your food. Cooking kills Cryptosporidia. Do not eat or drink unpasteurised dairy products.
• Drink safe water. Avoid drinking water from lakes, rivers, springs, ponds or streams unless it has been filtered and chemically treated.
• If the public health department in your health board area advises boiling water in the event of a community outbreak of cryptosporidiosis, do not drink tap water unless you boil it.
  • Boiling water: boiling is the best extra measure to ensure that your water is free from Cryptosporidia and other infections. After boiling the water for 1 minute, put it in a clean bottle with a lid and store it in the fridge. Use this water for drinking, cooking or making ice.
  • Filtering tap water: make sure the filters are designed to remove Cryptosporidium oocysts.
  • Bottled water: make sure bottled drinking water and carbonated drinks have been processed by a method effective against Cryptosporidium oocysts.

Take extra care when travelling. If you are travelling to developing nations, you may be at greater risk of cryptosporidiosis and other infections because of poorer water treatment and food preparation. Talk to your doctor about guidelines for travel abroad.

Based on the CDC Fact Sheet, Preventing Cryptosporidiosis: A guide for people with compromised immune systems.

Last updated: 30th March 2007