Cryptosporidiosis

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Cryptosporidiosis

• Blair Buder
• BIO 488L
• March 14, 2006

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Characteristics of the Pathogen

• Cryptosporidium
• Single-celled protozoan
• Obligate intracellular pathogen
• Infects the small intestine, causing
  gastroenteritis
• Completes whole life cycle within a single host
• Displays little host specificity
• Infectious oocyte is very thick-walled
• Protects it against chemical disinfectants
• Stable in the environment

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Cryptosporidium Images
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How Cryptosporidium Causes Disease

• Invades the intestinal epithelial cells
• Attaches using a lectin adherence factor
• In response to the attachement, the host cells
  release cytokines
• Stimulates phagocytosis
• Causes intestinal secretions and prevents
  absorption
• i.e. histamine, prostaglandins, PAF, serotonin

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Disease Causation Continued

• Reproduction occurs asexually within the host
  cells
• Kills these cells
• Produces thick-walled oocytes
• Oocytes are released in the hosts stools

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Symptoms

• Primarily watery diarrhea
• Abdominal cramps/ pain
• Nausea/ loss of appetite
• Dehydration
• Fever
• Vomiting
• Flatulence

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Symptom Characteristics

• Usually begin 2-10 days after infection
• Oocytes can be shed in stools for months
• More severe and longer lasting for the
  immunocompromised
• Prolonged diarrhea and dehydration
• Some people exhibit no symptoms at all

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Transmission

• Passes into the stools of infected people or
  animals
• Most infection occurs via the fecal-oral route
• Eating or drinking anything that has come into
  contact with contaminated feces
• Swallowing surface or recreational contaminated
  water
• Eating contaminated food that has not been
  thoroughly washed or cooked
• Can be carried onto food by the legs of
  cockroaches
• Very contagious
• Can be through the oral-anal route
• Cannot be transmitted though blood

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History of Cryptosporidium

• Discovered by Ernest Edward Tyzzer in 1907
• Was thought to be only a veterinary problem
• First found in humans in 1976
• The number of human cases rose along with the
  AIDS epidemic in the 1980s
• First spread through a water system was in
  Carollton, GA in 1987
• 13,ooo infected
• In 1993 was the worlds largest municipal water
  supply outbreak in Milwaukee, WI
• 400,ooo infected
• In 2001 EPA water requirements were increased to
  control crypto contamination

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Diagnosis

• Cannot be done on symptoms alone
• Requires a fecal sample
• To be used in fecal smears
• For direct detection of oocyte presence
• Acid-fast stains done

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Who is at Highest Risk?

• Children in day-care
• Child-care workers
• Parents
• People in close social groups
• People working with animals
• Swimmers
• Outdoorsmen who might drink unfiltered water
• International travelers
• Into developing nations
• People with shallow wells
• The immunocompromised
• Those who engage in unprotected oral-anal sex

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Treatment of Infection

• The immunocompetent will usually recover on their
  own within two weeks
• Staying hydrated
• Are no approved antibiotic treatments yet
• Nitazoxanide and azithomycin effectiveness is
  currently being tested
• Immunocompromised may be given hydration and
  nutrient therapy intravenously

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Prevention Mechanisms

• Frequent hand-washing, especially
• After going to the bathroom
• Before preparing food
• After contacting children, esp. diaper-aged
• Not swimming in pools within a month of being
  infected
• Thoroughly washing all fruit and vegetables to be
  eaten raw

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Prevention Continued

• Boil water when
• Traveling to developing countries
• Backpacking, camping, or hiking
• If using shallow ground wells
• If especially immunocompromised, i.e. gt200 TH
  cells
• Use a tap filter with a pore size of gtµm
• Practice safe and responsible sex habits
• Dont swallow pool water

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References

• Cryptosporidium. Kenyon College Biology
  Department. Hannahs, G.2006.
• Water Treatment Notes. Cryptosporidium a
  Waterborne Pathogen. USDA Water Quality Program.
  Kneen, B., Darling, S., Lemley, A. 2004
• Center for Disease Control and Prevention.
  Parasitic Disease Information Cryptosporidium
  Infection. www.cdc.gov. 2005.
• Environmental Protection Agency. Safe Drinking
  Water- Guidance for People with Severely Weakened
  Immune Systems. www.epa.gov. 1999.
• U.S. FDA. Foodborne Pathogenic Microbe Handbook.
  Cryptosporidium parvum. www.foodsafety.gov.
  2005.
• Cryptosporidium parvum. Ohio State University
  Biology Department. www.biosci.ohio-state.edu.
  2005.

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Quiz Question

• What could be an effective water treatment
  mechanism?
• Filtration through charcoal
• UV radiation
• Chlorination
• Voodoo
• Ozone radiation
• Both B. and E.