Shilpa.K Microbiology Tutor AIMSRC
Cryptosporidium parvumEnteric parasiteOne of the three most common diarrhea-
causing pathogens in the world
PrevalenceFound in most parts of the worldMost prevalent in Asia, Africa, Australia,
South AmericaAntibody prevalence in Peru and Venezuela –
64%32% in Peace Corps workersMore prevalent in rural areas of U.S.
More animal contact
TransmissionFecal-oral routeFomitesWater
Drinking water (even after treatment)Swimming pools
Unpasteurized Apple CiderAnimal contactFood
InfectivityC. parvum has a low ID50 (9-1000 oocysts)Can be infected by just one oocyst10 billion oocysts per gram infected feces
Life Cycle
http://www.dpd.cdc.gov/dpdx/HTML/Cryptosporidiosis.asp?body=Frames/A-F/Cryptosporidiosis/body_Cryptosporidiosis_life_cycle_lrg.htm
Life Cycle
http://www.dpd.cdc.gov/dpdx/HTML/Cryptosporidiosis.asp?body=Frames/A-F/Cryptosporidiosis/body_Cryptosporidiosis_life_cycle_lrg.htm
OocystDouble walled
Resistant to chlorine, drying, progressive freezing, salt water
Only stage in life cycle that can live ex vivoImbeds itself in gut epithelium and releases
sporozoitesReproduction continues sexually and asexually
Life Cycle
http://www.dpd.cdc.gov/dpdx/HTML/Cryptosporidiosis.asp?body=Frames/A-F/Cryptosporidiosis/body_Cryptosporidiosis_life_cycle_lrg.htm
Clinical CharacteristicsSecretory diarrhea (some mucous, but no
blood)Slight fever, fatigue, myalgiaOocysts may infect the lungs and trachea,
resulting in coughDehydration and extreme weight loss in
immunocompromised
DetectionAcid-fast stain of infected fecesDirect 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
TreatmentNitazoxanide
Interferes with folate productionPrevents parasite replication
ImmunocompetentC. parvum will usually pass on its own
ImmunocompromisedAIDS patients: treat with antiretrovirals and
strengthen immune system, no cureOthers: would not benefit from antiretrovirals;
keep hydrated
PreventionWater filtration
Filters must be <1 um to filter oocystSwimming pools
Must be drained if infected fecal accidentPasteurizationHand washing
Particularly in daycares
C. Parvum (left) and Giardia intestinalis (right)
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/cryptosporidiosis/factsht_crypto_prevent_water.htm
OutbreaksMilwaukee, WI 1993; 400,000 peopleGainesville, FL 1995; day campNew York 1996; unpasteurized apple cider