Cryptosporidiosis

• Cryptosporidiosis [krip-toe-spo-rid-ee-OH-sis] is a parasitic illness that causes diarrhea. It is an important emerging infection in the United States.
• Cryptosporidiosis parasites are passed in the stool of infected persons and animals. People get cryptosporidiosis when they swallow the parasites. Sources of disease include parasite-containing stool, food, and water.
• Anyone can get cryptosporidiosis, but persons with weakened immune systems can develop serious, life-threatening illness.
• There is no specific treatment for cryptosporidiosis.
• Cryptosporidiosis can be prevented by washing hands, drinking safe water, eating safe food, and avoiding all contact with the stool of infected persons or animals.

What is cryptosporidiosis?

Cryptosporidiosis is a parasitic illness that causes diarrhea.

What is the infectious agent that causes cryptosporidiosis?

Cryptosporidiosis is caused by Cryptosporidium parvum, a microscopic one-celled parasite that can live in the intestines of humans, farm animals, wild animals, and pets.

The parasite is protected by an outer shell called an OOCYST [oh-oh-cist]. This protective shell allows it to survive outside the body for a long time. When a person or animal swallows a Cryptosporidium oocyst, the parasite comes out of its shell and can cause infection. Then, more oocysts are produced and passed in the stool of the infected person or animal.

Where is cryptosporidiosis found?

Cryptosporidium parasites can be found anywhere in the environment that is contaminated by animal droppings or human waste. Cryptosporidium oocysts can contaminate soil and the food grown in it. They can get onto objects and surfaces that people touch. They can get into lakes, rivers, streams, and pools where people swim. They are also in many of the reservoirs that provide drinking water in the United States.

How do people get cryptosporidiosis?

People get cryptosporidiosis by swallowing Cryptosporidium oocysts. Even a few can cause infection. Some sources of cryptosporidiosis are:

Human and animal waste

• Diapers, clothing, bedding, or other items can be soiled with stool from an infected person or animal.
• Infected persons might have small amounts of Cryptosporidium-containing stool on their skin in the genital area. Sexual activities that might involve contact with stool can lead to infection with Cryptosporidium.
• The feces of animals, especially young animals and animals with diarrhea, can contain Cryptosporidium. People can be exposed to the parasite when touching animals, cleaning up their droppings, cleaning cages or stalls, or visiting barns and other places where animals live.

Food

• Food can be grown in or can fall on soil contaminated with human or animal waste.
• Unpasteurized milk and dairy products can be contaminated after contact with stool from an infected animal.
• Food can be contaminated when it is handled by someone who is infected or when it is washed with Cryptosporidium-contaminated water.

Water

• Water in lakes, rivers, streams, ocean bays, swimming pools, hot tubs, and recreational water parks can be contaminated with Cryptosporidium. People can get cryptosporidiosis if they drink this water or accidentally swallow it when swimming. Neither the chlorine used to disinfect swimming pools nor the types of filters used in most pools can be depended on to kill or remove Cryptosporidium.
• Contaminated drinking water or ice can be a source of Cryptosporidium infection. Unlike most disease-causing organisms, Cryptosporidium is not completely removed or killed by the treatment methods most commonly used for drinking water.

What are the signs and symptoms of cryptosporidiosis?

• Watery diarrhea
• Stomach cramps
• Upset stomach
• Slight fever

People with healthy immune systems will usually have symptoms for 2 weeks or less, although during that time symptoms might improve and then worsen. People who recover from their initial illness can continue to pass Cryptosporidium in their stool for up to 2 months. During this 2-month period they can spread the disease to others. Although some people who swallow Cryptosporidium oocysts will not get sick, they can still pass the organism in their stool.

People with severely weakened immune systems often cannot clear the parasite. They can suffer more severe diarrhea that can last long enough to be life threatening. People with HIV infection, cancer and transplant patients taking certain immune-suppressing drugs, and persons with inherited diseases that affect the immune system should talk to their health-care providers about how to avoid cryptosporidiosis.

How soon after exposure do symptoms appear?

Symptoms appear 2 to 10 days after swallowing Cryptosporidium oocysts.

How is cryptosporidiosis diagnosed?

Cryptosporidiosis is diagnosed in a laboratory by examining a stool sample for oocysts. A health-care worker who suspects cryptosporidiosis must specifically order testing for Cryptosporidium, since routine tests do not test for this parasite.

Who is at risk for cryptosporidiosis?

Anyone can get cryptosporidiosis, but some persons are at increased risk:

• Child-care workers and diaper-aged children who attend day-care centers
• Persons who take care of infected persons at home or in a group setting
• Persons exposed to human stool during sexual contact
• Persons with weakened immune systems, such as cancer patients, organ transplant recipients, and persons with HIV infection

What is the treatment for cryptosporidiosis?

There is no specific treatment for cryptosporidiosis. Healthy persons with normal immune systems usually get better on their own. The recommended treatment is to drink plenty of fluids and to get extra rest. Doctors may prescribe medicine to slow the diarrhea. Young children and persons with weakened immune systems might need special treatment from an health-care provider to replace fluids lost during the illness.

How common is cryptosporidiosis?

Cases of cryptosporidiosis occur singly and in outbreaks. Individual cases have been reported most often in persons with weakened immune systems, and infection with Cryptosporidium is among the most common causes of diarrhea in persons with AIDS in the United States. With the help of new techniques to diagnose the infection, however, cases in persons with healthy immune systems are being reported more often.

Six well-documented outbreaks of cryptosporidiosis attributed to municipal drinking water have been recognized in the United States, including an outbreak in Milwaukee, Wisconsin, that affected more than 400,000 persons. The sources of drinking water linked to these outbreaks included surface water (lakes, rivers, streams), well water, and spring water. Studies show that Cryptosporidium oocysts are in 65% to 97% of surface water tested around the country. Outbreaks have also been associated with swimming pools and amusement park wave pools and water slides.

Is cryptosporidiosis an emerging infectious disease?

Yes. Cryptosporidiosis is an important emerging infection in the United States and a cause of severe, life-threatening disease in persons with weakened immune systems. Cryptosporidium was recognized as a cause of human disease in 1976, but was rarely reported until 1982, when cases increased dramatically as part of the HIV/AIDS epidemic. Still, few people had heard of cryptosporidiosis until the 1993 outbreak in Milwaukee. Since then, concern about the safety of drinking water in the United States has increased, and attention has been focused on determining and reducing the risk for cryptosporidiosis from water supplies and other sources.

How can cryptosporidiosis be prevented?

The risk of infection associated with each of the sources of Cryptosporidium parasites is still unknown. Until more is learned about this organism, it is important to follow these basic prevention steps:

• Keep hands clean. Wash hands thoroughly with soap and warm water after using the toilet, after changing diapers, and before handling or eating food. Wash hands well after touching faucet handles, clothing, bedding, toilets, or bed pans soiled by someone with diarrhea. Wash hands after gardening, after cleaning up after pets or other animals, and after touching anything that might have had contact with even small amounts of human or animal stool. Supervise children to make sure they wash their hands well.
• Avoid sexual activity that might involve contact with stool.
• Drink safe water. Know the source of your drinking water. Avoid swallowing water when swimming in lakes, rivers, the ocean, or pools, and when using hot tubs. When camping or traveling in a less developed region, avoid drinking water that has not been boiled or filtered to remove Cryptosporidium.
• Eat safe food. Prepare food carefully. Wash all vegetables or fruits that you eat raw, even those that you peel before eating. Wash foods with purified (boiled or filtered) water. Use only pasteurized milk, dairy products, juices, and ciders.
• Comply with any water advisories issued by local and state authorities.

What extra precautions should persons with weakened immune systems take to reduce the risk?

Cryptosporidiosis can be a severe, life-threatening disease in persons with weakened immune systems. If you have a weakened immune system, talk to your health-care provider about the need for extra precautions to minimize the risk of infection. These might include the following steps:

• Boil all drinking water, or use filters or bottled water for all drinking water, including water for tooth brushing.
• Wash hands thoroughly after any contact with stool.
• Avoid sexual practices that can result in hand or mouth exposure to stool.
• Avoid direct exposure to cattle and other farm animals. If exposure cannot be avoided, wash hands well immediately after contact.

This fact sheet is for information only and is not meant to be used for self-diagnosis or as a substitute for consultation with a health-care provider. If you have any questions about the disease described above or think that you might have a parasitic infection, consult a health-care provider.

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