ID
Cryptosporidium parvum
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Cryptosporidium parvum
, Cryptosporidium, Cryptosporidiosis, Cryptosporidium hominis, Cryptosporidia
See Also
Diarrhea
Infectious Diarrhea
Waterborne Illness
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
N Engl J Med (1994) 331:161 [PubMed]
MMWR (1996) 45:442-5 [PubMed]
Sexually transmitted in
Men who have Sex with Men
Effects 10-20% of advanced HIV patients
Risk Factors
Day care center attendance
Human Immunodeficiency Virus
(HIV) infection
Pathophysiology
Coccidian protozoan present in animal feces
Farm animals
Domestic pets
Very low inoculum required: 10 Oocysts
Immunocompetent host has only mild
Diarrhea
l illness
Immunocompromised host has potentially severe or even fatal illness (gastrointestinal and respiratory effects)
AIDS
patients
CD4 Count
<200: Chronic, persistent
Diarrhea
CD4 Count
<140: More severe symptoms
Symptoms
Normal Host
Diarrhea
Abdominal Pain
Nausea
or
Vomiting
Fever
HIV Infection
or other immunocompromised patient
Chronic, persistent, secretory, watery
Diarrhea
Cough
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
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)
Stool
s may exceed 21 stools per day for months (with secondary malabsorption and
Failure to Thrive
)
Complications
Reactive Arthritis
(associated with C hominis)
Extra-intestinal infection (immunocompromised patients)
Lung
s 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
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 Inhibitor
s may have additional activity against Cryptosporidium
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]
Resources
Cryptosporidium
http://www.cdc.gov/parasites/crypto/
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]
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