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Additional Information on Prevention Cryptosporidiosis for Persons Who are Immunocompromised

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Do the precautions listed for persons with healthy immune systems apply to me?
Yes. See the VDH Cryptosporidiosis Fact Sheet. If you are HIV positive, undergoing chemotherapy, taking drugs that suppress the immune system (e.g., corticosteroids) or are otherwise immunocompromised, you should take additional precautions:

  • Be extra careful about what you eat and drink.
      °  Wash vegetables and fruits that will be eaten raw.
      °  Be careful not to let raw foods contaminate other foods.
  • Be especially careful about hand washing, including after touching animals or working with soil.
  • Avoid swallowing water from lakes, rivers, or swimming pools.
  • Follow safer-sex guidelines.
  • Take extra care when travelling, especially to developing countries where food and water may be contaminated with Cryptosporidium or other pathogens.

What about my drinking water?
Current data are inadequate to recommend that all immunocompromised persons boil or avoid drinking tap water in non-outbreak settings. However, you may want to discuss the need for taking further protective measures with your healthcare provider because:

  • Drinking water that is considered safe for persons with healthy immune systems may contain some Cryptosporidium oocysts (the egg-like form of the organism).
  • No one knows whether a few oocysts could create a risk for someone who is immunocompromised.
  • Oocysts ingested while you are healthy may remain in your body until your immune system is severely depressed and then cause serious illness.

What are some options for safer beverages?
Bring tap water to a full boil for one minute before using.

  • This will kill all organisms including Cryptosporidium.
  • To avoid burning yourself, allow water to cool before pouring into clean, dry containers.
  • Taste can be improved by adding lemon or other flavorings.
  • Use the boiled water for ice cubes, tooth brushing and mixing with concentrates. You don't need to use boiled water for food that will be cooked before eating.
  • Dishes, silverware, and pots may be washed with tap water as long as they are dry before being used.

Use a point-of-use (personal-use, end-of-tap, or under sink) filter that will remove particles 1 micron or less in diameter. Filters in this category include:

  • Those that use reverse osmosis
  • Those labeled as "Absolute" 1 micron filters
  • Those labeled as meeting NSF (National Sanitation Foundation) Standard #53 or Standard #58 for "Cyst Removal or Reduction". (Note: The "Nominal" 1 micron filter rating is not standardized and filters may not remove oocysts.)

Follow directions for filter use and to replace the filters according to manufacturer’s directions. Wear disposable gloves when changing filter cartridges. More information on filters is available at

Use bottled water only if it has been processed in a way that will remove Cryptosporidium oocysts.

  • Bottled water does not have to meet the same standards as water coming from a treatment plant.
  • Bottled water that has been distilled or passed through filters that remove particles 1 micron or less in size or that has undergone reverse osmosis prior to bottling will not have Cryptosporidium oocysts.

Use commercially bottled soft drinks and seltzers.

  • Bottled juices are safe if they have been pasteurized and do not require refrigeration before opening
  • Avoid fountain drinks, fruit drinks from frozen concentrate, iced tea made from untreated water, and fresh apple cider.

Where can I obtain additional information?

See the Centers for Disease Control and Prevention (CDC) website at for more information.

Additional information for healthcare providers who care for immunocompromised patients may be found at (for adult patients) and (for pediatric patients). 

Last Updated: 09-28-2011

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