Cryptosporidiosis is an infection that causes diarrhea. It is sometimes called crypto. It is caused by a parasite found in stool. You can get this infection after eating food or drinking water that is contaminated with stool. This includes swallowing water while swimming or drinking from infected streams and other water sources. You can also get infected if you touch things or surfaces contaminated with stool. You can also get the infection from another person.

The parasite has an outer shell. Because of this shell, using chlorine to clean water may not kill the parasite. Cryptosporidiosis is one of the most common causes of waterborne disease in the U.S.

Cryptosporidiosis is caused by the parasite Cryptosporidium. After it is inside your body, the parasite passes through your digestive tract and infects your intestines and stool. Anything contaminated with the infected stool can pass the infection on to other people.

The parasite is found throughout the world. But you are more likely to get the infection if you travel to rural areas in developing countries. Or you can get it if you eat or drink in areas where sanitation is poor. Outbreaks have also occurred in the U.S. when water supplies or swimming pools become infected.

The disease is spread by swallowing anything that has come into contact with the stool of a person or animal with the infection. This includes:

• Swallowing water contaminated with the parasite. The parasite can be found in swimming pools, hot tubs, lakes, rivers, springs, ponds, or streams contaminated with sewage or stool.
• Eating uncooked foods tainted with the parasite.
• Swallowing the parasite after it has been picked up from surfaces contaminated with the stool of an infected person. This includes bathroom fixtures, changing tables, and diaper pails.
• Touching your mouth with contaminated hands. This is a particular risk in child care facilities because you have a greater chance of contact with contaminated surfaces and stool (diaper changing).

Cryptosporidiosis is normally not a serious disease in healthy people. But it can lead to a life-threatening illness for people who have a weak immune system. Those at risk are:

• People who have HIV or AIDS.
• Cancer and transplant patients who are taking certain medicines that suppress the immune system.
• People who have inherited diseases that affect the immune system.

Each person may have slightly different symptoms. The most common symptoms are:

• Diarrhea.
• Loose or watery stools.
• Vomiting.
• Weight loss.
• Stomach cramps.
• Fever.

You may not have any symptoms. If symptoms do develop, they often last about 2 weeks but sometimes longer. But even if you have no symptoms, the parasite is passed in your stool for up to 2 months. During this time, you are at risk of spreading the infection to others.

Your doctor will test a stool sample. Sometimes multiple stool samples (usually three) will be needed since this parasite is found only intermittently in the stool. You will need special testing because tests for this disease are not routinely done in labs.

Most people with a healthy immune system don't need to be treated. Cryptosporidiosis will resolve on its own. In those who have a weak immune system, the focus of treatment is often on getting the immunity back. Otherwise, the medicine nitazoxanide or paromomycin can be used to treat this parasite. Sometimes you may be given an antidiarrheal medicine such as loperamide to ease symptoms.

No treatment works fully against the infection. If you have a healthy immune system, you will likely recover on your own. People who are in poor health or have a weak immune system may get a more serious infection. In some cases, you may need to take medicine for diarrhea. It's important to drink plenty of fluids to stay hydrated.

There is no vaccine to prevent cryptosporidiosis. The best way to protect yourself is with good personal hygiene and by avoiding or appropriately disinfecting potentially contaminated water before drinking it. Also:

• Wash your hands thoroughly with soap and water after using the toilet or changing diapers.
• Wash your hands thoroughly before eating or making food.
• Wash and peel all raw fruits and vegetables before eating.
• Don't drink water from lakes, rivers, springs, ponds, or streams, unless the water has been filtered or chemically treated.
• Don't drink any water or eat any food that may be tainted.
• When traveling to countries where the water supply may be unsafe, do not drink unboiled tap water. Also, do not eat any raw foods washed with tap water. Choose steaming hot drinks, such as coffee and tea, and pasteurized fruit drinks. Make sure bottled water is safe to drink.
• Many home and camping or hiking water filters can remove Cryptosporidium. Read the label for details.

Contact your doctor right away if your symptoms return or get worse, or if you have new ones.

• Cryptosporidiosis is an infection that causes diarrhea. It is caused by a parasite.
• Most people get the parasite after swallowing food or water tainted with stool. This includes swallowing water while swimming.
• Diarrhea, vomiting, stomach cramps, and weight loss are the most common symptoms.
• Dehydration is the main complication.
• People who have a healthy immune system usually recover without treatment. People with a weak immune system may get a more serious infection and need medical care.
• Good personal hygiene can help prevent it. You should also stay away from unclean water sources.

Tips to help you get the most from a visit to your doctor:

• Know the reason for your visit and what you want to happen.
• Before your visit, write down questions you want answered.
• Bring someone with you to help you ask questions and remember what your doctor tells you.
• At the visit, write down the name of a new diagnosis and any new medicines, treatments, or tests. Also write down any new instructions your doctor gives you.
• Know why a new medicine or treatment is prescribed and how it will help you. Also know what the side effects are and when they should be reported.
• Ask if your condition can be treated in other ways.
• Know why a test or procedure is recommended and what the results could mean.
• Know what to expect if you do not take the medicine or have the test or procedure.
• If you have a follow-up appointment, write down the date, time, and purpose for that visit.
• Know how you can contact your doctor if you have questions, especially after office hours and on weekends and holidays.