II. Epidemiology
- Natural Hosts: Young animals (e.g. calves)
- C. hominis only infects humans
- C. parvum infects both cows, sheep and humans
- Foodbourne illness (fecal-oral route transmission)
- Common cause of Traveler's Diarrhea worldwide
- Contaminated drinking water or uncooked foods
- Foods contaminated by an infected food handler
-
Waterborne Illness outbreaks
- Milwaukee contaminated municipal water (n=400,000)
- Florida Summer Camp with contaminated outdoor faucet
- References
- Sexually transmitted in Men who have Sex with Men
- Effects 10-20% of advanced HIV patients
III. Risk Factors
- Day care center attendance
- Human Immunodeficiency Virus (HIV) infection
IV. Pathophysiology
- Coccidian protozoan present in animal feces
- Farm animals
- Domestic pets
- Very low inoculum required: 10 Oocysts
- Immunocompetent host has only mild Diarrheal illness
- Immunocompromised host has potentially severe or even fatal illness (gastrointestinal and respiratory effects)
V. Symptoms
- Normal Host
- HIV Infection or other Immunocompromised patient
VI. Labs
- Specific Ova and Parasite testing
- Cryptosporidium is not typically included on routine Ova and Parasite testing
- Request specific testing if higher index of suspicion
- May require multiple stool samples collected on several different days (intermittent excretion)
- Diagnostic modalities
- PCR (gold standard)
- Microscopy (wet mount, stains)
- Immunohistologic testing (immunoassay against oocyst wall)
- Sample sources
- Stool
- Duodenal aspirate
- Bile secretions
- Respiratory secretions
VII. Course
- Symptom onset delayed 2-10 days from exposure (up to 2 weeks)
- Normal host (self-limited)
- Diarrhea persists for 10 days in normal host (self limited)
- May relapse over weeks to months in some cases
-
Immunocompromised host
- Severe course (may be fatal)
- Stools may exceed 21 stools per day for months (with secondary malabsorption and Failure to Thrive)
VIII. Complications
- Reactive Arthritis (associated with C hominis)
- Extra-intestinal infection (Immunocompromised patients)
- Lungs are commonly affected (with secondary cough), esp. with C. hominis
- Chronic biliary tract disease (sclerosing Cholangitis) in patients with comorbid HIV Infection
- Other involvement
- Conjunctivitis
- Esophagitis
- Appendicitis
- Pancreatitis
- Intestinal perforation
IX. Management
- Symptomatic management
- See Acute Diarrhea
- Most immunocompetent patients recover without specific treatment
- Immunocompetent patients with severe or prolonged Diarrhea
- Nitazoxanide (Alinia) 500 mg orally twice daily for 3 days
- Paromomycin and Azithromycin are not thought to be effective
- Cure rate 72% with treatment, and resolves spontaneously in most cases
-
Immunocompromised patients or HIV positive
- Nitazoxanide (Alinia) is no more effective than Placebo in Immunocompromised patients
- However may be trialed in age over 1 year old
- Paromomycin and Azithromycin may be trialed in refractory cases (but low efficacy)
- Highly Active Antiretroviral Therapy in HIV eradicates intestinal Cryptosporidium (especially if CD4 >150 cells/mm3)
- Protease Inhibitors may have additional activity against Cryptosporidium
- Nitazoxanide (Alinia) is no more effective than Placebo in Immunocompromised patients
X. Prevention
- Avoid swimming for 1-2 weeks after exposure (oocyst sheddling continues after resolution)
- Water filters or boiling water (for at least one minute) reduces infection risk
- Cryptosporidium is very resistant to halogens (e.g. chlorination, Iodine)
- Swimming pool chlorination does NOT prevent transmission
- Cryptosporidium oocysts survive >10 days in swimming pools chlorinated to CDC recommended levels
- Shields (2008) J Water Health 6(4): 513-20 [PubMed]
XI. Resources
- Cryptosporidium
XII. References
- Wang and Nguyen (2017) Crit Dec Emerg Med 31(9):13-8
- Checkley (2015) Lancet Infect Dis 15(1): 85-94 [PubMed]
- Perkins (2017) Am Fam Physician 95(9):554-60 [PubMed]
- Weller (2001) BMJ 322:1350-4 [PubMed]