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Related to cryptosporidiosis: giardiasis, toxoplasmosis




Cryptosporidiosis refers to infection by the sporeforming protozoan known as Cryptosporidia. Protozoa are a group of parasites that infect the human intestine, and include the better known Giardia. Cryptosporidia was first identified in 1976 as a cause of disease in humans.


Cryptosporidia are normally passed in the feces of infected persons and animals in the form of cysts. The cysts can remain in the ground and water for months, and when ingested produce symptoms after maturing in the intestine and the bile ducts. When viewed under the microscope, they appear as small bluish-staining round bodies. Most common sources of infection are other humans, water supplies, or reservoirs. These are contaminated by animals that defecate in these areas. An outbreak in Milwaukee in 1993 in which over 400,000 persons were affected was traced to the city's water supply. Cysts of Cryptosporidia are extremely resistant to the disinfectants that are commonly used in most water treatment plants and are incompletely removed by filtration.
Most persons who experience significant symptoms have an altered immune system, and suffer from diseases such as AIDS and cancer. However, as shown in the Milwaukee outbreak, even those with normal immunity can experience symptoms.

Causes and symptoms

Cysts of Cryptosporidia mature in the intestine and bile ducts within three to five days of ingestion. As noted, large-scale infections from contaminated water supplies has been documented. However, human to human transmission (such as occurs in day care centers or through sexual behavior) is also an important cause.
Many individuals can be infected without any illness, but the major symptom is diarrhea, which is often watery and incapacitating. Dehydration, low-grade fever, nausea, and abdominal cramps are frequent.
In those with a normal immune system, the disease usually lasts about 10 days. For patients with altered immunity (immunocompromised), the story is quite different, with diarrhea becoming chronic, debilitating, and even fatal.


Dehydration and malnutrition are the most common effects of infection. In about 20% of AIDS patients, bile duct infection also occurs and causes symptoms similar to gallbladder attacks. Eighty percent or more of those with infection of the bile ducts die from the disease. The lungs and pancreas are also sometimes involved. Cryptosporidia are just one cause of the diarrhea wasting syndrome in AIDS, which results in severe weight loss and malnutrition.


This is based on either finding the characteristic cysts in stool specimens, or on biopsy of an infected organ, such as the intestine.


The first aim of treatment is to avoid dehydration. Oral Rehydration Solution (ORS) or intravenous fluids may be needed. Medications used to treat diarrhea by decreasing intestinal motility (Anti-Motility Agents), such as loperamide or diphenoxylate, are also useful, but should only be used with the advice of a physician.
Treatment aimed directly at Cryptosporidia is only partially effective, and rarely eliminates the organism. The medication most commonly used is paromomycin (Humatin), but others are presently under evaluation.


Cryptosporidia rarely cause a serious disease in persons with normal immune systems. Replacement of fluids is all that is usually needed. On the other hand, those with altered immune systems often suffer for months to years. Paramomycin and other drugs have been able to improve symptoms in over half of those treated. Unfortunately, many organisms are resistant, and recurrence is frequent.


The best way to prevent cryptosporidiosis is to minimize exposure to cysts from infected humans and animals. Proper hand washing technique, especially in day care centers, is recommended.



Centers for Disease Control and Prevention. 1600 Clifton Rd., NE, Atlanta, GA 30333. (800) 311-3435, (404) 639-3311.


"Cryptosporidiosis." Centers for Disease Control.
Vakil, Nimish B., et al. "Biliary Cryptosporidiosis in HIV-Infected People after the Waterborne Outbreak of Cryptosporidiosis in Milwaukee." New England Journal of Medicine Online.

Key terms

Anti-motility medications — Medications such as loperamide (sold as Imodium), dephenoxylate (sold as Lomotil), or medications containing codeine or narcotics that decrease the ability of the intestine to contract. This can worsen the condition of a patient with dysentery or colitis.
Cyst — A protective sac that includes either fluid or the cell of an organism. The cyst enables many organisms to survive in the environment for long periods of time without need for food or water.
Immunocompromised — A change or alteration of the immune system that normally serves to fight off infections and other illnesses. This can involve changes in antibodies that the body produces (hygogammaglobulinemia), or defect in the cells that partake in the immune response. Diseases such as AIDS and cancer exhibit changes in the body's natural immunity.
Oral Rehydration Solution (ORS) — A liquid preparation developed by the World Health Organization that can decrease fluid loss in persons with diarrhea. Originally developed to be prepared with materials available in the home, commercial preparations have recently come into use.
Parasite — An organism that lives on or in another and takes nourishment (food and fluids) from that organism.
Protozoa — Group of extremely small single cell (unicellular) or acellular organisms that are found in moist soil or water. They tend to exist as parasites, living off other life forms.
Spore — A resistant form of certain species of bacteria, protozoa, and other organisms.
Gale Encyclopedia of Medicine. Copyright 2008 The Gale Group, Inc. All rights reserved.


infection with protozoa of the genus Cryptosporidium, which may be associated with or contribute to enteric disease in calves, lambs, foals, and piglets. Human infection occurs both in immunocompetent persons, in whom it causes a self-limited diarrhea syndrome, and in immunocompromised patients, in whom it is much more serious, being manifested clinically as prolonged debilitating diarrhea, weight loss, fever, and abdominal pain, with occasional spread to the trachea and bronchial tree.
Miller-Keane Encyclopedia and Dictionary of Medicine, Nursing, and Allied Health, Seventh Edition. © 2003 by Saunders, an imprint of Elsevier, Inc. All rights reserved.


An enteric disease that is tranferred by waterborne or fecal contamination routes; caused by protozoan parasites of the genus Cryptosporidium; characterized pathologically by villous atrophy and fusion and clinically by diarrhea in humans, calves, lambs, and other animals; disease in immunocompetent people is usually manifest as a self-limiting diarrhea, whereas in immunocompromised people it is manifest as a prolonged severe diarrhea that can be fatal.
Farlex Partner Medical Dictionary © Farlex 2012


An intestinal parasitic infection of some vertebrates caused by protozoa of the genus Cryptosporidium, characterized in some humans by chronic diarrhea.
The American Heritage® Medical Dictionary Copyright © 2007, 2004 by Houghton Mifflin Company. Published by Houghton Mifflin Company. All rights reserved.


Crypto, cryptosporidium enterocolitis An opportunistic infection caused by Cryptosporidium parvum, an animal parasite Epidemiology Oral-fecal transmission; it grows in the intestines and bile ducts especially immunocompromised and HIV-infected Pts Clinical Cryptosporidium enterocolitis causes watery diarrhea, abdominal pain, flatulence, fever; CDC considers chronic intestinal cryptosporidiosis ≥ 1 month an AIDS-defining condition Management No standard therapy Proposed therapy Paromomycin–humatin, azithromycin, letrazuril, concentrates of cow and chicken antibodies
McGraw-Hill Concise Dictionary of Modern Medicine. © 2002 by The McGraw-Hill Companies, Inc.


An enteric disease caused by waterborne protozoan parasites of the genus Cryptosporidium; disease in immunocompetent people is seen as a self-limiting diarrhea, whereas in immunocompromised people it is manifest as a prolonged severe diarrhea that can be fatal.
Medical Dictionary for the Health Professions and Nursing © Farlex 2012


An infection with the protozoal organism Cryptosporidium parvum first described in humans in 1976. It is now known to be a common cause of self-limiting acute gastroenteritis occurring in otherwise healthy people, especially children. It is a common cause of travellers' diarrhoea. In those with AIDS or other causes of immune deficiency, however, it may be a life-threatening infection with a mortality of 50 per cent. Infection is direct or indirect via drinking water, from humans or animals. Cryptosporidium is one of the more common bowel pathogens. When treatment is necessary this may involve fluid infusion for dehydration and the use of drugs such as paromomycin (Humatin), somatostatin, azidothymidine, diloxanide furoate, furazolidone, amprolium, and the macrolide antibiotics. Unfortunately, none of the current antimicrobial dugs are reliably effective.
Collins Dictionary of Medicine © Robert M. Youngson 2004, 2005
References in periodicals archive ?
Heavy economic losses have been reported due to cryptosporidiosis in different animal husbandry practices (Ramo et al., 2016).
The general manager further explained cryptosporidium, which is a parasite that causes Cryptosporidiosis, "is a spore baring bug that is protected in environments like guts and swimming environments with chlorine, and the spore protects that bug from being harmed by regular amounts of chlorine."
"If a cryptosporidiosis outbreak occurs, substantial decontamination measures are needed, including hyperchlorinating public treated recreational water venues (e.g., swimming pools at a hotel, apartment complex, or water park) and using hydrogen peroxide to disinfect surfaces in child care settings to inactivate Cryptosporidium oocysts," they emphasized.
Centers for Disease Control and Prevention in Atlanta, and colleagues examined outbreaks of cryptosporidiosis for 2009 to 2017 for 40 states and Puerto Rico.
A cryptosporidiosis outbreak was defined as two or more cases epidemiologically linked to a common source by location and time of exposure.
Cryptosporidiosis can be transmitted in a number of ways including person-toperson and bathing in contaminated water, including at swimming pools.
"Cryptosporidiosis and campylobacter are generally mild infections and in most cases the symptoms of abdominal pain and diarrhoea settle in a few days.
Several large waterborne outbreaks of cryptosporidiosis have been reported (5,7,8).
It is indicated as an aid in the diagnosis of gastrointestinal infection when giardiasis, cryptosporidiosis and amebiasis is suspected.
Experts in infectious disease from Novartis (VTX: NOVN), who teamed up with the University of Georgia and Washington State University last year, have announced the discovery and early validation of a drug candidate for treating cryptosporidiosis, Novartis reported on Thursday.
The major symptoms related to cryptosporidiosis are similar to that of the Cholera and other coccidian infections.