Medical quality assurance by Dr. Albrecht Nonnenmacher, MD at August 3, 2016

Cryptosporidium are also referred to as 'Crypto' and the scientific name, 'Cryptosporidium parvum'. This is a parasite that causes a gastrointestinal disease called Cryptosporidiosis which is both highly preventable and curable. Cryptosporidium can infect both humans and animals. 


Definition & Facts

The Cryptosporidium parasite is comprised of a single cell. It is so small that it cannot be seen without a microscope. One characteristic that makes this parasite so tenacious is its outer shell. This shell enables the parasite to survive in harsh conditions. Cryptosporidium is quite resistant to chlorine and can live outside the body for extended periods of time.

It infects people through drinking water and recreational water sources. According to the United States Center for Disease Control or CDC, Cryptosporidium is a leading cause of waterborne illness in the United States. 

If infection does occur, most healthy people do not suffer serious long-term effects. It is not a common disease but the causal parasite is found in every region in the world. An estimated 748,000 cases of Cryptosporidium occur each year in the United States alone.

Symptoms & Complaints

This parasite causes symptoms that vary from person to person. Some people who contract Cryptosporidium have no noticeable symptoms. Those who do notice symptoms typically do so between two and 10 days after infection. While cryptosporidiosis is characterized mainly by watery diarrhea, there are other symptoms that can occur as well.

Nausea, stomach cramps, vomiting, and fever are commonly associated with this parasitic disease. Vomiting and fever often cause dehydration and weight loss as well. Symptoms associated with Crypto can last as long as 30 days in some people though most people do not have symptoms for longer than seven days. 

The severity of this disease depends primarily on the health of the person who contracts it. Those who have pre-existing conditions that affect the immune system may have more severe symptoms.

People who have HIV or other diseases that cause a weakened immune system can develop a life-threatening condition associated with Cryptosporidium. Those who have cancer and who are taking medications that suppress the immune system are also at an increased risk of developing severe symptoms. 


Cryptosporidium is primarily contracted through water. Drinking contaminated water is the primary source of infection. Eating uncooked food that has been contaminated will also cause symptoms. Drinking unpasteurized fruit juices can lead to infection. Fresh juices can also be easily infected. Since there is no heat used in processing, the parasite lives in the juice.

People can also be infected by touching feces that contain the parasite. If the mouth is touched after touching the feces, the person can become infected via the fecal-oral route. Cryptosporidium is not spread through contact with blood or semen.

Certain people are at an increased risk of developing Crypto. Those who work at daycare centers, have young children, international travelers and campers are more likely to develop this disease. Drinking from shallow wells, streams and handling infected livestock can also cause infection. This parasite has been known to contaminate water sources in residential areas and water parks. People who work as lifeguards or pool cleaners are at an increased risk of infection. 

Diagnosis & Tests

Diagnosis of the Cryptosporidium parasite is made by examining stool samples. It can be difficult to diagnose this condition, and patients are sometimes asked to bring in multiple stool samples. It is often diagnosed over the course of several days. Samples are examined under the microscope for evidence of the parasite. Testing for this parasite is not routine, so physicians must specifically request it. 

Treatment & Therapy

Healthy people with normal immune systems often recover from this disease with no treatment. However, it is often necessary to take in extra fluids to prevent dehydration while diarrhea, fever, and vomiting are present. Severe diarrhea may warrant anti-diarrhoeal medications.

Prolonged vomiting may also require medication for nausea. Those who have serious medical conditions such as AIDS or cancer, can require medication to avoid serious complications.

Nitazoxanide which is an antiparasitic drug is used to treat cryptosporidiosis. It cures the infection and rids the body of the parasite in 60-75 percent of cases while relieving diarrhea in 72-88 percent of cases, according to the Centers for Disease Control and Prevention.

Prevention & Prophylaxis

There are numerous ways to reduce the risk of contracting this parasite. Hand washing is key to prevention. Hot water and antibacterial soap is one way to prevent infection. It is important to wash for a full 20 seconds and rinse the hands thoroughly. Cryptosporidium cannot be killed by the use of hand sanitizer, as it is resistant to it.

Since the parasite can also be spread through contaminated food, it is important to cook everything completely to avoid infection. Other ways to prevent infection include not swallowing pool water and washing hands after handling animals and after changing small children's diapers. According to the Centers for Disease Control and Prevention, it is also best to avoid swimming if diarrhea is present.

Since Cryptosporidium is spread through contact with feces, it can be contracted through certain forms of sexual contact involving the anus. Practicing safe sex is the best way to avoid this. Hand washing after touching a sex partner's genital area or anus is also important. 

Because cryptosporidium is most commonly contracted through water, safety is important. Avoiding drinking water from rivers, streams or lakes is important. Those who want to take extra precautions at home can purchase a water filter system, and buying bottled water can may also help prevent infection. Abiding by any boil water notices in residential areas is also key to prevention. Heating water to a rolling boil will kill this parasite within one minute.

It is also important to take necessary precautions when traveling in developing countries as Cryptosporidium is more common in these regions. Since sanitation is not always optimal in developing countries, one should avoid consuming raw fruits or vegetables when traveling to such regions.

It is important to see a doctor if infection of this parasite is suspected. This is especially important for those with health conditions that compromise the immune system. Early detection and treatment is vital when dealing with any parasitic infection. The faster the diagnosis, the more options physicians have regarding treatment. The prognosis for recovery is good in people who are generally healthy.