Cyclosporiasis and Cryptosporidiosis

Cyclosporiasis (sy-klo-spor-I-a-sis) and cryptosporidiosis (krip-to-spo-rid-e-Osis) also called crypto, are infections in the intestines that result from eating or drinking food or water contaminated by the parasites Cyclospora cayetanensis and Cryptosporidium parvum. These infections can result in diarrhea, stomach cramps, and nausea.

The Milwaukee Story

Thousands of people in Milwaukee, Wisconsin, started to get sick in early 1993 during the time that the Frozen Four, the college ice hockey finals, were being played there. They had stomach pains, nausea, fever, and diarrhea, as if perhaps they had influenza. But authorities soon discovered that dangerous one-celled parasites * were in the city's water supply. When people drank the contaminated water, cryptosporidiosis developed.

In the end, more than 400,000 people came down with symptoms of cryptosporidiosis. More than 100 people died, including many who had diseases that weaken the immune system, such as AIDS * . The parasite had entered the water system from human waste in Lake Michigan, a water source for the city. Filters on the city's water plant had not removed the parasite though the root cause was never determined. This event was the largest waterborne disease outbreak in documented U.S. history.

How Do People Get Cyclosporiasis and Cryptosporidiosis?

Cryptosporidiosis and cyclosporiasis, a closely related illness, are common infections that result from contaminated water and food. They (and similar illnesses) affect millions of people worldwide and are especially dangerous to children, the elderly, and people with diseases that weaken the immune system, such as AIDS. The infections are common in developing nations, but they also are found increasingly in developed nations that import food, such as the United States. Findings from the Centers of Disease Control and Prevention (CDC) and the U.S. Food and Drug Administration on the U.S. Cyclospora outbreak from May to August 2015 that sickened 546 people from 31 states indicated that some illnesses among residents in these states were linked to fresh cilantro from Puebla, Mexico.

Cyclosporiasis and cryptosporidiosis result when humans eat food or drink water containing the cyst form of microscopic parasites from infected human or animal waste. The Cyclospora cayetanensis and Crypto-sporidium parvum parasites can also enter the human body when people touch objects that have come in contact with infected fecal matter and then place fingers in their mouths. Fresh fruits and vegetables can become contaminated if they are irrigated with water that contains the parasites.

Did You Know?

Intestinal infections such as cyclosporiasis and cryptosporidiosis are among the most common illnesses in the world. As of 2015, 1.5 million people worldwide (mostly in low-income and developing countries) die from illnesses that cause severe diarrhea each year, a drop in diarrhea-associated deaths compared to statistics from 1982 through 2000. In 2014, about 304 cases of cyclosporiasis were reported to the U.S. Centers for Disease Control and Prevention.

Additionally, as the ease and frequency of global travel have increased and as importation of food sources has increased, these infections gained the ability to spread from one part of the world to another in very short periods of time.

What Happens When People Get Cyclosporiasis and Cryptosporidiosis?


Although caused by different parasites, cyclosporiasis and cryptosporidiosis may cause similar symptoms: watery diarrhea, stomach pain, nausea, fever, and vomiting. Weight loss, due to the diarrhea, and loss of appetite are also common. The first symptoms of cyclosporiasis often appear a week after the parasite enters the body, but the first symptoms of cryptosporidiosis may appear as soon as two days after infection or as long as 10 days after. The illnesses can last for a few days to two weeks. Infections from cyclosporiasis sometimes last more than a month and return one or more times.


It can be hard to diagnose cyclosporiasis and cryptosporidiosis, because many illnesses can cause similar symptoms. If doctors suspect these infections, they may order tests to examine patients' stool for signs of the parasites.


The danger of intestinal infections such as cyclosporiasis and cryptosporidiosis is dehydration * from the loss of water through diarrhea. Doctors remind patients to drink plenty of fluids, such as water and sports drinks. Cyclosporiasis can also be treated with antibiotics * . Cryptosporidiosis, however, has no specific drug cure. Usually, people completely recover from either illness in a week or two. People with AIDS and other diseases that weaken the immune system need extra medical attention, because they are at higher risk of more severe and more prolonged infections.

How Are These Infections Prevented?

Intestinal infections such as cyclosporiasis and cryptosporidiosis are among the most common illnesses in the world. Several preventive measures can lower the chances of getting these or similar intestinal illnesses:

Some people choose to drink only bottled water or use special filters for drinking water and ice. When overseas, especially when in developing nations, travelers should not drink tap water or use ice made from tap water. It also is recommended that fruits and vegetables be avoided by individuals who travel outside the United States, unless they can be cooked or peeled.

See also Parasitic Diseases: Overview


Books and Articles

Wisconsin Division of Public Health, Department of Health Services. “Disease Fact Sheet Series: Cyclosporiasis.” (accessed December 1, 2015).


U.S. Food and Drug Administration. “Environmental Assessment: 2013. Cyclosporiasis Outbreak in Iowa and Nebraska—Findings and Recommendations.” (accessed December 1, 2015).


Centers for Disease Control and Prevention. 1600 Clifton Rd., Atlanta, GA 30333. Toll-free: 800-311-3435. Website: (accessed December 1, 2015).

U.S. Environmental Protection Agency. 1200 Pennsylvania Ave. NW, Washington, DC 20004. Telephone: 202-564-4700. Website: (accessed December 1, 2015).

U.S. Food and Drug Administration. 10903 New Hampshire Ave., Silver Spring, MD 20993. Toll-free: 888-463-6332. Website: (accessed May 2, 2016).

* parasites (PAIR-uh-sites) are organisms such as protozoa (one-celled animals), worms, or insects that must live on or inside a human or other organism to survive. An animal or plant harboring a parasite is called its host. Parasites live at the expense of the host and may cause illness.

* AIDS or acquired immunodeficiency (ih-myoo-no-dih-FIH-shensee) syndrome, is an infection that severely weakens the immune system; it is caused by the human immunodeficiency virus (HIV).

* dehydration (dee-hi-DRAY-shun) is a condition in which the body is depleted of water, usually caused by excessive and unreplaced loss of body fluids, such as through sweating, vomiting, or diarrhea.

Disclaimer:   This information is not a tool for self-diagnosis or a substitute for professional care.

(MLA 8th Edition)