In people with weakened immune systems, such as HIV infected persons, cancer patients, and organ transplant recipients, cryptosporidiosis can be serious, long-lasting and sometimes fatal.

Last updated: 29 November 2016

What is cryptosporidiosis?

Cryptosporidium is a parasite that can cause diarrhoea (cryptosporidiosis). Cryptosporidium infections have been reported in humans and a variety of animals such as cattle and sheep.

What are the symptoms of cryptosporidiosis?

Symptoms usually include diarrhoea, stomach cramps and often fever, nausea and vomiting. The first symptoms may appear 2 to 12 days after a person becomes infected. People with normal immune systems usually have symptoms for one to two weeks and then recover fully.

How does cryptosporidiosis affect you if your immune system is severely weakened?

In people with weakened immune systems, such as HIV infected persons, cancer patients, and organ transplant recipients, cryptosporidiosis can be serious, long-lasting and sometimes fatal. If your CD4+ cell count is low, cryptosporidiosis is more likely to cause diarrhoea and other symptoms for a long time.

How is cryptosporidiosis spread?

The Cryptosporidium organism is present in the faecal matter of infected humans and animals. Therefore cryptosporidiosis can be spread by person to person contact, particularly in child care centres, by not washing hands after going to the bathroom or after changing babies nappies; by contaminated water or food; handling of infected pets or farm animals, or their faeces; and certain sexual activity.

Can cryptosporidiosis be treated?

There is no specific treatment for cryptosporidiosis. If you think you have cryptosporidiosis, or if you have diarrhoea, talk with your doctor about testing and treatment. Diarrhoea can cause dehydration. You should drink plenty of fluids to prevent dehydration. Oral rehydration powders can also help prevent dehydration.

How can I protect myself from cryptosporidiosis?

You can reduce your risk of getting cryptosporidiosis. The following actions will also help protect you against other diseases.

  1. Wash your hands. Washing your hands often with soap and water is probably the single most important step you can take to prevent cryptosporidiosis and other illnesses. Always wash your hands before eating and preparing food; after touching children in nappies; after touching objects soiled by someone who has diarrhoea; after gardening and after touching pets or other animals. Even if you wear gloves when you do these activities you should still wash well when you finish. Children should be supervised by adults to make sure they wash their hands well.
  2. Practice safer sex. Infected people may have Cryptosporidium on their skin in the anal and genital areas, including the thighs and buttocks. Immunosuppressed people should avoid sexual practices such as oral/anal intercourse that may lead to exposure to faeces.
  3. Avoid touching farm animals. If you touch a farm animal wash your hands well with soap and water before preparing food or putting anything in your mouth. Avoid touching the faeces of any animals.
  4. Avoid touching the stool of pets. Most pets are safe to own. However, someone who is not HIV infected or otherwise immuno-suppressed should clean their litter boxes or cages, and dispose of the faeces. If you must clean up after a pet, use disposable gloves. Wash your hands afterwards. The risk of getting cryptosporidiosis is greatest from young pets, animals that have diarrhoea, and stray animals.
  5. Be careful when swimming in lakes, rivers, or pools, and when using hot tubs. When swimming in lakes, rivers, or pools, and when using hot tubs, avoid getting water in your mouth. Several outbreaks of cryptosporidiosis have been traced to swallowing contaminated water while swimming. Cryptosporidium is not killed by the amount of chlorine normally used in swimming pools and water parks.
  6. Wash and/or cook your food. Fresh vegetables and fruits may be contaminated with micro-organisms. Therefore, wash well all vegetables or fruit you will eat uncooked. If you take extra steps to make your water safe, use this safe water to wash your fruits and vegetables. When you can, peel fruit that you will eat raw, after washing it. Do not eat or drink unpasteurised milk or dairy products. Thorough cooking kills Cryptosporidium.
  7. Drink safe water. Do not drink water directly from lakes, rivers, streams, or springs.

Several outbreaks of cryptosporidiosis around the world have been linked to contaminated water supplies. In water supplies not linked to outbreaks the risk of infection is difficult to determine, but is quite low. There is insufficient evidence to recommend that all HIV-infected and immuno-suppressed people avoid drinking tap water altogether. However people who wish to avoid possible risks from tap water may, after consultation with a doctor, choose to observe the following precautions: boil tap water, filter water with certain home filters, or drink certain types of bottled water.

Boiling water

Bringing water to a rolling boil is sufficient to inactivate Cryptosporidium and other microorganisms. This can be achieved by a number of methods, although care should be taken to avoide scalding. Kettles with automatic shut off switches are sufficient for this purpose and should reduce the risk of scalding. After the boiled water cools, put it in a clean bottle or container with a lid and store it in the refrigerator. Use the water for drinking, cooking, or making ice.

Filtering tap water

Filters will be effective in removing Cryptosporidium if they are capable of removing all particles larger than one micron. Some filters are labelled "one micron" but are in fact only nominally one micron and may let some much larger particles pass through. Suitable filters should meet the relevant standards for cyst removal. The standards are ANSI/NSF standard 53 (1997) or AS4348:1995. A filter labelled "absolute 1 micron" is suitable if it meets the above standards. Activated carbon filters without microstraining are not effective against Cryptosporidium. Reverse osmosis filters will remove Cryptosporidium.

Filters labelled only with these words may not be designed to remove Cryptosporidium: effective against parasites; carbon filter; water purifier; removes chlorine; ultraviolet light; pentiodide resins; water softener.

Filters collect germs from your water, so someone who is not HIV infected should change the filter cartridges for you; if you do it yourself, wear gloves and wash your hands afterwards. Poor filter maintenance or failure to replace filter cartridges as recommended by the manufacturer can cause your filter to fail. The manufacturer's directions on maintenance should be carefully observed.

Bottled water

If you choose to drink bottled water, read the label. The following methods are known to be effective against Cryptosporidium: reverse osmosis treated; distilled; filtered through an absolute 1 micron or smaller filter "1 micron absolute".

Water labelled as follows may not have been processed by a method effective against Cryptosporidium: filtered; micro-filtered; carbon-filtered; particle-filtered; multimedia-filtered; ozonated; ozone-treated; ultraviolet light-treated; activated carbon-treated; carbon dioxide-treated; ion exchange-treated; deionised; purified; chlorinated.

Other drinks

some beverages have the potential to contain Cryptosporidium depending on their method of preparation. Cryptosporidium is killed or removed in the preparation of: canned or bottled soda, drinks prepared from boiled water e.g. tea, coffee; pasteurised drinks.

Cryptosporidium may not be killed or removed in the preparation of: fountain drinks; unpasteurised drinks; fruit drinks you mix with tap water from frozen concentrate; iced tea or coffee. Juices made from fresh fruit can also be contaminated with Cryptosporidium.

Take extra care when travelling

If you travel to developing countries you may be at a greater risk for cryptosporidiosis and other diseases because of poorer water treatment and food sanitation. Avoid certain food and drink, in particular raw fruits and vegetables, tap water, or ice made from tap water, unpasteurised milk or dairy products, and items purchased from street vendors. Fruit you peel yourself and hot coffee or tea made using boiled water, are safe. Talk with your health care provider about other guidelines for travel abroad.

Further inform​ation

In NSW call 1300 066 055 to talk to your local Public Health Unit.

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