Cryptosporidium parvum

cryptosporidium

1. Shilpa.K
Microbiology Tutor
AIMSRC

2. Cryptosporidium parvum
Enteric parasite
One of the three most common diarrhea-causing
pathogens in the world

3. Prevalence
Found in most parts of the world
Most prevalent in Asia, Africa, Australia, South
America
Antibody prevalence in Peru and Venezuela – 64%
32% in Peace Corps workers
More prevalent in rural areas of U.S.
More animal contact

4. Transmission
Fecal-oral route
Fomites
Water
Drinking water (even after treatment)
Swimming pools
Unpasteurized Apple Cider
Animal contact
Food

5. Infectivity
C. parvum has a low ID
50
(9-1000 oocysts)
Can be infected by just one oocyst
10 billion oocysts per gram infected feces

6. Life Cycle
http://www.dpd.cdc.gov/dpdx/HTML/Cryptosporidiosis.asp?body=Frames/A-F/Cryptosporidiosis/body_Cryptosporidiosis_life_cycle_lrg.htm

7. Life Cycle
http://www.dpd.cdc.gov/dpdx/HTML/Cryptosporidiosis.asp?body=Frames/A-F/Cryptosporidiosis/body_Cryptosporidiosis_life_cycle_lrg.htm

8. Oocyst
Double walled
Resistant to chlorine, drying, progressive freezing, salt
water
Only stage in life cycle that can live ex vivo
Imbeds itself in gut epithelium and releases
sporozoites
Reproduction continues sexually and asexually

9. Life Cycle
http://www.dpd.cdc.gov/dpdx/HTML/Cryptosporidiosis.asp?body=Frames/A-F/Cryptosporidiosis/body_Cryptosporidiosis_life_cycle_lrg.htm

10. Clinical Characteristics
Secretory diarrhea (some mucous, but no blood)
Slight fever, fatigue, myalgia
Oocysts may infect the lungs and trachea, resulting in
cough
Dehydration and extreme weight loss in
immunocompromised

11. Detection
Acid-fast stain of infected feces
Direct immunofluorescence antibody stain using
monoclonal antibody to oocyst wall
Modified acid-fast oocyst
stain
http://www.dpd.cdc.gov/dpdx/HTML/ImageLibrary/Cryptosporidiosis_il.htm

12. Treatment
Nitazoxanide
Interferes with folate production
Prevents parasite replication
Immunocompetent
C. parvum will usually pass on its own
Immunocompromised
AIDS patients: treat with antiretrovirals and
strengthen immune system, no cure
Others: would not benefit from antiretrovirals; keep
hydrated

13. Prevention
Water filtration
Filters must be <1 um to filter oocyst
Swimming pools
Must be drained if infected fecal accident
Pasteurization
Hand washing
Particularly in daycares
C. Parvum (left) and Giardia
intestinalis (right)

14. Bottled Waters
“not all are created equal”
Water so labeled has been processed by method effective against crypto
Reverse osmosis treated
Distilled
Micro-filtered
Filtered through an absolute 1 micron or smaller filter
"One micron absolute"
Water so labeled may not have been processed by method effective against crypto
Carbon-filtered
Filtered
Particle-filtered
Multimedia-filtered
Ozonated
Ozone-treated
Ultraviolet light-treated
Activated carbon-treated
Carbon dioxide-treated
Ion exchange-treated
Deionized
Purified
Chlorinated
http://www.cdc.gov/NCIDOD/DPD/parasites/cryptos
poridiosis/factsht_crypto_prevent_water.htm

15. Outbreaks
Milwaukee, WI 1993; 400,000 people
Gainesville, FL 1995; day camp
New York 1996; unpasteurized apple cider

16. Summary
Cryptosporidiosis caused by cryptosporidium parvum
Transmitted via fecal-oral route
Oocyst stage in life cycle is resilient
Oocyst imbeds itself in gut epithelium
Infection usually occurs from tainted water, even if it
has been treated
No cure in immunocompromised