FAQs: Cryptosporidium

What you need to know about Cryptosporidium in drinking water

In recent years we have learned that specific microbial pathogens, such as Cryptosporidium, are resistant to traditional disinfection practices. Cryptosporidium has attracted close attention since 1993, when 400,000 people in Milwaukee suffered intestinal illness as a result of contamination in the water supply. The outbreak hospitalized more than 4,000 people, and the disease caused at least 50 deaths. Additionally, there have also been cryptosporidiosis outbreaks in Nevada, Oregon, and Georgia over the past several years.

Amendments to the Safe Drinking Water Act in 1996 required EPA to develop rules(1) to balance the risks and to strengthen protection against microbial contaminants, especially Cryptosporidium. Treating water that contains Cryptosporidium oocysts is the first line of defense against an outbreak.

Effective methods for getting rid of Cryptosporidium(1) include appropriate chemical treatment, filtration and boiling.

Frequently Asked Questions

What is Cryptosporidium?

Cryptosporidium is a one-celled parasite that can cause a gastrointestinal illness called cryptosporidiosis.

Where does it come from?

Cryptosporidium occurs in the feces of infected animals or humans. It is environmentally resistant and may survive outside the body for long periods of time. To become infected, a person must consume contaminated food or water, including water from streams or rivers.

What are the symptoms of cryptosporidiosis?

Symptoms include diarrhea, abdominal cramps, headaches, nausea, vomiting and a low-grade fever. These symptoms can last for weeks and may result in weight loss and dehydration. Symptoms are more severe for people with weakened immune systems and can lead to death.

Who are people with weakened immune systems?

Those on chemotherapy, organ or bone marrow recipients, persons with HIV or AIDS, malnourished children, the very young and the very old.

When do symptoms appear?

From two to 12 days after ingestion. The average is seven days.

How is it spread?

Infection results from consuming contaminated water or food. Direct or hand-to-mouth transfer of the parasite from human or animal feces can also cause infection. Animal feces may infect streams or lakes and in turn infect swimmers or hikers drinking untreated water.

What is the treatment for cryptosporidiosis?

If you think you may have cryptosporidiosis, see a health care provider, especially if you have a weakened immune system. For people with healthy immune systems, most recover without treatment; however, treatment is available that may reduce symptoms. See your doctor.

Who is at risk?

Anyone exposed to feces is at risk. This includes:

  • people drinking contaminated water while camping or traveling;
  • child care workers; young children who attend child care centers;
  • persons exposed to human feces by sexual contact;
  • caregivers who might come in contact with feces while caring for a person infected with cryptosporidiosis.

Farm animals and farm products (such as unpasteurized apple cider) have caused exposures. Children are especially susceptible because they put so many things into their mouths.

How common is cryptosporidiosis?

Cryptosporidium has world-wide distribution. About 4-5% of the world population has cryptosporidiosis. Scientists originally identified it as a parasite of animals, reptiles and birds, until research detected it as a source of illness for humans in 1976. Health officials now believe Cryptosporidium has been causing human illnesses for a long time, but difficulties in testing and diagnosis caused clinicians to overlook it. A specific parasite test for Cryptosporidium can be done at the request of a health care provider.

How can I ensure that my water is safe to drink?

Pay attention to health advisories and boil-water notices. To ensure that your drinking water is safe during boil-water notices, always boil or filter your water, or use bottled water:

  • Boiling water is the best way to ensure that your water is free of Cryptosporidium and other microorganisms. Bring the water to a rolling boil for one minute. After it cools, put it in the refrigerator in clean bottles or pitchers with a lid. Use boiled water to brush your teeth, make ice, and rinse raw food, and to make baby formula or coffee (coffee makers do not get hot enough to kill Cryptosporidium).
  • Water filters can collect Cryptosporidium and other microorganisms from the water, but may not be as effective as boiling. Read the water filter label. Only those with the following messages are effective for Cryptosporidium:
           "Tested and certified by NSF standard 53 for cyst removal,"
           "Tested and certified by NSF standard 53 for cyst reduction,"
           "Reverse osmosis,"
           "Absolute micron size of one micron or smaller."
  • To find out if a particular filter removes Cryptosporidium, contact NSF International (3475 Plymouth Road, PO Box 130140, Ann Arbor, MI, 48113-0140, 1-800-673-8010, fax: 1-313-769-0109), an independent testing group. Ask for a list of "Standard 53 Cyst Filters.
  • Bottled water may be a reasonable alternative to tap water, but the origin, quality and treatment of water before bottling varies considerably among companies and even among brands of water from the same company. Generally, water labeled as follows is free of Cryptosporidium:
           "Reverse osmosis treated,"
           "Filtered through an absolute one micron or smaller filter."
  • Carbonated water in cans or bottles is usually safe to drink. Avoid fountain drinks made from tap water during boil-water notices.

What else can I do to avoid cryptosporidiosis?

The single most effective way to avoid illness is to wash your hands often with soap and water. During boil-water advisories, use boiled and cooled, filtered, or safely bottled water for washing dishes, fruits and vegetables.

  • Always wash your hands before handling food and dishes and after using the toilet, gardening, changing diapers or handling pets or farm animals, particularly young animals like calves.
  • Wash fruits and vegetables with safe water, especially if you plan to eat them raw. You can also peel fruit that you will not cook.
  • Never cook for other people if you have diarrhea.
  • Avoid unpasteurized milk or dairy products and unpasteurized juices. Cooking kills Cryptosporidium and other microorganisms.
  • Do not swim in public pools or lakes if you have diarrhea.
  • Don't swallow any water from lakes, rivers, pools or Jacuzzis. Water swallowed accidentally while swimming may contain the organism.
  • Take care when traveling in developing countries. Foods and drinks, in particular raw fruits and vegetables, tap water or ice made from tap water, unpasteurized milk or dairy products, and items from street vendors may be contaminated with Cryptosporidium. Talk to your health care provider about other precautions you may want to take when traveling abroad.

Are these recommendations sufficient for people with weak immune systems?

For most people, yes. However, persons with AIDS should use disposable gloves or have someone else who is not HIV-positive change the cartridges on their water filter. Because of other infections, take the same precautions with cat-litter boxes, or for contact with wild birds, wild animals, or farm animals.

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