Basics
Description
Cryptosporidiosis is protozoal infection causing a self-limited acute gastroenteritis characterized by nonbloody watery diarrhea. á
- Symptoms, when present, can also include abdominal pain, fever, fatigue, weight loss, vomiting, headache, and joint pain and typically last 1-2 weeks.
- In an immunocompromised patient, gastrointestinal symptoms can be chronic, relapsing, and severe, causing profound and life-threatening wasting and malabsorption.
- Extraintestinal: Pulmonary, biliary tract (sclerosing cholangitis, acalculous cholecystitis, pancreatitis), or disseminated infection rarely occurs among immunocompromised individuals.
Epidemiology
- Oocysts of Cryptosporidium are shed in stool of infected hosts (humans, cattle, and other mammals) and are transmitted by fecal-oral contamination.
- Disease is most commonly associated with contamination of water sources, both drinking and recreational, and transmission is also seen in association with child care centers or livestock.
- Cryptosporidium has been found in all parts of the world and is a cause of traveler's diarrhea.
- Because of summer recreational water use, the incidence of cryptosporidiosis is highest in children and typically peaks in summer through early fall.
Incidence
- In 2010, nearly 9,000 new cases were reported in the United States. The incidence began increasing in 2005, with a peak in 2007 at just over 11,500 cases.
Risk Factors
- Those most at risk of infection are children who attend day care centers, people who take care of others with cryptosporidiosis (including child care workers, parents of infected children, and health care workers), those who swim in or drink from contaminated water sources such as streams or unprotected wells, and people who handle livestock including those visiting petting zoos.
- Because Cryptosporidium are chlorine tolerant, swimming in chlorinated pools does not decrease the risk of infection.
General Prevention
- Drinking water should be adequately filtered to a particle size of 1 ╬╝m or smaller in order to ensure oocyst removal.
- If a recreational water supply becomes contaminated, it should be closed and proper decontamination measures should be implemented.
- Those diagnosed with cryptosporidiosis should not swim for at least 2 weeks after diarrhea stops to help protect others.
- Good hand hygiene, washing with soap and water vigorously for at least 20 seconds, is key after contact with animals or stool.
- Children with diarrhea should not attend day care settings until diarrhea is resolved.
- In day care settings, disinfection of diapering areas after each use and frequent disinfection of toys, tabletops, and highchairs during outbreaks is recommended.
- Oocysts can survive for long periods and are resistant to many disinfectants including chlorine, iodine, and dilute bleach. Boiling water or full-strength bleach disinfectant is most effective.
- Contact precautions are recommended for the length of the hospital stay for hospitalized patients.
- Immunocompromised persons should avoid contact with any person or animal with cryptosporidiosis.
Pathophysiology
- Transmission occurs via fecal-oral passage of oocysts from food, water, or poor hand hygiene.
- The incubation period is typically 3-14 days with a median of 7 days, and oocyst shedding may occur for weeks to months after symptoms resolve. In the majority of people, shedding stops after 2 weeks. Immunocompromised patients can shed for several months.
- Invasion of intestinal epithelial cells in the small intestine and proximal colon leads to a secretory diarrhea.
- Intestinal destruction occurs with villous atrophy and subsequent malabsorption and increased intestinal permeability.
Diagnosis
History
- Acute onset of symptoms combined with exposure to any of the transmission sources discussed above should prompt consideration. Fever and vomiting are symptoms more commonly found in children and can lead to the misdiagnosis of viral gastroenteritis.
- Immunocompromised patients such as those with AIDS may have chronic severe symptoms with significant wasting.
Physical Exam
- Acute weight loss
- Fever
- Tenderness to palpation of abdomen
- Dehydration
- Immunocompromised patients may rarely exhibit respiratory symptoms (dyspnea) or biliary tract symptoms (colicky right upper quadrant pain).
Diagnostic Tests & Interpretation
Lab
- Detection of organisms in stool specimens is diagnostic. Oocysts are small and may be missed on routine light microscopic examination of stool; modified acid-fast staining may aid in diagnosis.
- Fluorescent stains such as auramine O are rapid but have high false-positive rates.
- Immunofluorescent assays and enzyme-linked immunosorbent assays for antigen detection are also available.
- The direct immunofluorescent stain is the diagnostic test of choice.
- Tests for Cryptosporidium are not routinely performed and should be specifically requested.
Differential Diagnosis
- Other infectious etiology of diarrheal illness:
- Viral gastroenteritis including rotavirus, adenovirus, astrovirus; caliciviruses including norovirus, cytomegalovirus
- Bacterial gastroenteritis including Salmonella, Shigella, Yersinia, Campylobacter, enterotoxigenic Escherichia coli, Vibrio cholerae
- Clostridium difficile enterocolitis
- Parasitic gastroenteritis including Giardia, Entamoeba, Cyclospora, Isospora, Microsporidia
- Noninfectious etiology of diarrheal illness:
- Allergic colitis, inflammatory bowel disease, irritable bowel syndrome, appendicitis, intussusception, malrotation/volvulus, celiac disease, or other malabsorption
Treatment
Medication
- In immunocompetent patients, disease is typically self-limited, and no treatment is necessary.
- For those who are malnourished where treatment is preferred, oral nitazoxanide may be given for 3 days.
- Dosage for children 1-3 years of age is 100 mg b.i.d.; for children 4-11 years of age, 200 mg b.i.d.; and for adults, 500 mg b.i.d.
- For immunosuppressed patients, antiretroviral therapy to improve CD4+ count has been associated with decreasing duration of illness. Nitazoxanide, paromomycin, and bovine immunoglobulin have also been tried without strong data to support efficacy.
Additional Therapies
General Measures
- Fluids and electrolytes should be replaced by oral or intravenous route.
Ongoing Care
Follow-up Recommendations
Patient Education
- Because the oocysts can be shed in the stool for weeks after clinical resolution, it is important to realize that asymptomatic patients can still transmit the infection to household and day care contacts.
- Requiring patients whose diarrhea has resolved to have a negative stool test for Cryptosporidium before reentry to day care has not been evaluated as an outbreak control measure. Repeated testing is expensive.
Prognosis
- For immunocompetent hosts, gastrointestinal disease is self-limited, usually lasting approximately 10 days. Supportive therapy is usually all that is necessary.
- For immunocompromised patients, diarrhea can be severe, debilitating, and often life threatening. Aggressive supportive therapy is usually required, along with antimicrobial therapy and immune reconstitution.
Additional Reading
- American Academy of Pediatrics. Cryptosporidiosis. In: Pickering áLK, Baker áCJ, Kimberlin áDW, et al, eds. Red Book: 2012 Report of the Committee on Infectious Diseases. 29th ed. Elk Grove Village, IL: American Academy of Pediatrics; 2012:296-298.
- Centers for Disease Control and Prevention. Parasites-Cryptosporidium (also known as "Crypto"Ł). http://www.cdc.gov/parasites/crypto/. Accessed November 5, 2013.
- Yoder áJS, Wallace áRM, Collier áSA, et al. Cryptosporidiosis surveillance-United States, 2009-2010. MMWR Surveill Summ. 2012;61(5):1-12. á[View Abstract]
Codes
ICD09
ICD10
SNOMED
- 58777003 Infection by Cryptosporidium (disorder)
- 66160001 Cryptosporidial gastroenteritis (disorder)
FAQ
- Q: For whom should cryptosporidiosis be considered as a differential diagnosis?
- A: For anyone with acute onset of watery diarrhea with any of the mentioned risk factors
- Q: When is it safe for a child with cryptosporidiosis to return to day care?
- A: When the diarrhea has resolved
- Q: For how long is an immunocompetent patient with cryptosporidiosis contagious?
- A: A healthy person may continue to shed for weeks to months after diarrhea has resolved.