Cryptosporidiosis is a parasitic infection of the small intestine. Diarrhea is the main symptom, but in people with compromised immune systems, the symptoms can be severe or even fatal.
The infectious parasite Cryptosporidium spreads via the fecal-oral route, often as a result of exposure to contaminated drinking or recreational water.
Some people may confuse cryptosporidiosis for cryptococcus, as both sometimes go under the name “crypto.” Cryptococcus is a type of invasive fungus that can cause cryptococcosis.
In the United States, nearly 750,000 people report to doctor’s offices with cryptosporidiosis every year. However, according to one 2019 study, many cases go unreported. The true extent of this is not clear.
This article will look at the symptoms of cryptosporidiosis, what causes it, and which treatments are available. It will also discuss ways to prevent transmission while swimming or drinking water.
In people with a healthy immune system, the main symptom of cryptosporidiosis is watery, self-limiting diarrhea.
Symptoms will normally start between 2 and 10 days after a person acquires the virus. However, the effects of the parasite can last anywhere from a few days to longer than 4 weeks.
A person with a healthy immune system may experience:
- watery diarrhea
- stomach pain or cramps
- nausea and vomiting
- weight loss
Diarrhea is usually watery with mucus. Rarely, there may also be blood or pus (white blood cells) in the diarrhea. Sometimes, however, a person who has cryptosporidiosis may not experience any noticeable symptoms at all.
People with compromised immune systems, such as those with uncontrolled HIV, have a higher risk of acquiring cryptosporidiosis and experiencing severe complications. Their immune systems may not be able to counter the infection effectively. As a result, these people may develop more severe, long-term, or fatal symptoms of cryptosporidiosis.
Also, the parasite can remain in their intestines and reactivate after periods of being dormant. It can still transmit to other people during these latent periods.
The parasite Cryptosporidium causes this infection. There are many species of Cryptosporidium, and they can infect humans and a wide range of animals. The individual microorganisms that cause cryptosporidiosis are known as oocysts.
A particular species called Cryptosporidium parvum has been responsible for 50.8% of cases in 325 global outbreaks of water-borne parasitic diseases across the world.
The oocysts that cause cryptosporidiosis have hard, protective outer shells. The high resistance of Cryptosporidium oocysts to disinfectants, such as chlorine bleach, enables them to survive for long periods and remain active outside of a host body.
Humans commonly acquire the infectious agent through consuming or swimming in contaminated water. Earth and uncooked or cross-contaminated food that has been in contact with the feces of an individual or animal who carries Cryptosporidium can also spread this disease.
A bowel movement in a person with cryptosporidiosis can release millions of oocysts in the feces. Other humans may acquire the parasite when they accidentally ingest the oocysts through the oral route.
It is prevalent among those who are in regular contact with fresh water, including swimming pools.
A person may acquire cryptosporidiosis in the following ways:
- putting anything in the mouth that has touched the feces of a person or animal who carries oocysts, such as following diaper changes in a daycare center
- swallowing beverages or recreational water that contains oocysts
- consuming raw or uncooked food that contains oocysts
- touching the mouth with the hands after making manual contact with a surface or substance that contains oocysts
Cryptosporidium oocysts can still transmit to others from a person who does not display symptoms or whose symptoms have resolved.
Cryptosporidiosis is not transmissible through contact with blood.
The following groups have an increased risk of ingesting Cryptosporidium oocysts and acquiring cryptosporidiosis:
- children who attend daycare facilities
- people who work with children, especially those who change diapers
- the parents of children who carry Cryptosporidium oocysts
- caregivers and healthcare workers who look after those with cryptosporidiosis
- people who travel, hike, camp, or backpack internationally and may have exposure to unfiltered and untreated water
- individuals who consume water from shallow wells that lack proper sanitation
- people who regularly swim in public pools and may swallow water that contains oocysts
- people who come into contact with or handle cattle that may carry cryptosporidiosis
- those who may have contact with human feces through sex
The parasites responsible for cryptosporidiosis occur in every part of the U.S. and all over the world. However, in countries with less effective water treatment and food safety, it can transmit to more people. This is because oocysts are more likely to remain in drinking water and food products.
In developing countries, cryptosporidiosis poses a serious health burden. In a 2019 study of children in a Cameroon hospital, for example, doctors found Cryptosporidium in 8.9% of children overall and in 13.4% of those who had diarrhea.
A study from 2016 found that 2.9 million and 4.7 million children under 24 months of age acquired cryptosporidiosis every year in sub-Saharan Africa and in the region containing India, Pakistan, Bangladesh, Nepal, and Afghanistan, respectively.
According to the study authors, cryptosporidiosis was responsible for 202,000 deaths in these areas.
To diagnose cryptosporidiosis, a doctor can usually first observe the initial symptoms after an incubation period of 2–10 days.
They will take a stool sample and send it to a laboratory for analysis. Cryptosporidiosis can be difficult to detect, so the doctor may request more than one stool sample over several days.
The stool culture can reveal the presence of the parasite. It can help rule out other infectious agents, too.
Antigen detection assays can confirm a diagnosis. Antigens are toxic or foreign substances in the body that trigger an immune response, and these tests highlight their presence.
Polymerase chain reaction tests can also help identify the particular species of Cryptosporidium.
A doctor may use an ultrasound to check for the effects of cryptosporidiosis in the bile system. The disease may have caused dilated or irregular bile ducts and a thickened gallbladder.
This, combined with laboratory testing, may help the doctor rule out other possible causes of diarrhea in the intestines.
Finally, an endoscopic retrograde cholangiopancreatography may confirm the diagnosis of biliary disease that can occur due to Cryptosporidium.
There are several treatment and management options for cryptosporidiosis. Most cases are self-limiting and require no treatment other than supportive care.
The Food and Drug Administration (FDA) have approved nitazoxanide, an antidiarrheal drug, for treating diarrhea symptoms due to cryptosporidiosis. It is an effective cure in 72–88% of cases.
However, healthcare professionals are less certain about its effectiveness in people with suppressed immune systems.
It is common for the infection to return.
Doctors recommend that people who receive treatment for cryptosporidiosis avoid activities such as swimming for at least 2 weeks after symptoms have resolved.
People who have or who have recently had cryptosporidiosis should not swim in communal areas. This is because the pathogen can spread from the anal area. The oocysts will continue to shed for some time.
It is also important to stay hydrated. A person with severe dehydration may need intravenous fluids.
Doctors usually reserve antibiotic recommendations for those with a severe presentation of the disease and a compromised immune system. This is because, in people with healthier immune systems, antibiotics can get rid of bacteria in the gut that may help relieve symptoms.
Treating the condition in people with compromised immune systems
Antiretroviral therapy is necessary to boost the immune systems of people with HIV. This can also “decrease or eliminate” symptoms of cryptosporidiosis, according to the Centers for Disease Control and Prevention (CDC).
Studies have suggested that drugs such as rifabutin and clarithromycin may also protect people from cryptosporidiosis when they take the drug to prevent Mycobacterium avium transmission in those who have HIV.
If a person with uncontrolled or advanced HIV has cryptosporidiosis, they are more likely to need active treatment than people with healthy immune systems.
They will also need to be monitored for volume depletion and electrolyte imbalance due to dehydration. A person may also require treatment for weight loss and malnutrition.
The best way to prevent cryptosporidiosis is to follow guidelines for hygiene and sanitation, including:
- washing the hands carefully before eating and after using the bathroom or any having potential contact with stool
- avoiding contact with animal feces and food and water that may carry Cryptosporidium
- washing and cooking all vegetables thoroughly
- when camping or hiking, using bottled or filtered water and avoiding drinks that contain ice
While swimming, there are several steps a person can take to reduce the risk of transmission. These include:
- not swallowing water
- not swimming or letting people swim if diarrhea symptoms are obvious
- waiting for 2 weeks following the resolution of cryptosporidiosis symptoms to enter a public swimming pool or share bathwater
- checking the diapers of any young children or taking them on bathroom breaks every 60 minutes
In childcare facilities, the best ways to reduce cryptosporidiosis transmission include:
- keeping children who have diarrhea symptoms away
- sanitizing and disinfecting toys and surfaces regularly
- moving adults with cryptosporidiosis symptoms to less risky roles, such as keeping them away from food preparation and moving them to administrative duties
- regularly washing the hands
Another means of protection is to avoid sexual activities that involve exposure to feces. People can practice hygienic sex in the following ways:
- using soap and water to wash the hands, anus, genitals, and any sex toys both before and after sex
- applying barrier contraception, such as condoms or dental dams, and using them in the correct way
- using latex gloves when inserting fingers or hands into the anus
People with compromised immune systems should take extra care to protect themselves from untreated water in lakes and streams.
Cryptosporidiosis is a transmissible disease that occurs due to the parasite Cryptosporidium. It most commonly causes watery diarrhea.
However, people with compromised immune systems may experience more severe, longer-term symptoms.
The parasite passes from person to person through the fecal-oral route. Transmission can occur in public swimming locations and as a result of drinking untreated water.
Treatment involves antiparasitic drugs, as well as rehydration and nutrition for those with severe symptoms.
Following hygiene and sanitation guidelines can help prevent transmission.