Shilpa.KMicrobiology 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

SummaryCryptosporidiosis caused by cryptosporidium

parvumTransmitted via fecal-oral routeOocyst stage in life cycle is resilient Oocyst imbeds itself in gut epitheliumInfection usually occurs from tainted water,

even if it has been treatedNo cure in immunocompromised