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CRYPTOSPORIDIUM SP
What is it?
Cryptosporidium is an emerging coccidian protozoan parasite
It is associated with municipal water supplies which causes diarrhea
Cryptosporidium parvum causes the disease Cryptosporidiosis.
During the past two decades, Cryptosporidium has become recognized as one of the most common causes of waterborne illness in the United States.
Definitive Host: Human
Reservoir Hosts: kittens, puppies, goats, calves, mice,etc
It is a zoonotic disease and can travel from animals to humans, and also from human to human
Transmission : fecal oral route food and water
Cryptosporidium parvum has been recognized as a human pathogen since 1976.
What is it?
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
Outbreak
In Milwaukee, WI water contamination from a sewage treatment plant killed 100 people and affected more than 400,000 in 1993. The parasite that caused the disease was determined to be cryptosporidium.
Infectivity & Life Cycle
C. parvum has a low ID50 (9-1000 oocysts)
Can be infected by just one oocyst 10 billion oocysts per gram infected
feces
http://www.dpd.cdc.gov/dpdx/HTML/Cryptosporidiosis.htm
Oocyst
Double walled, 4-6µm 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 Mature oocyst contain 4 sporozoites within
Site of infection
Epithelial cells of the gastrointestinal tract Has affected other tissues such as
respiratory tract tissues and conjunctiva of the eye.
Cell death is a direct result of parasite invasion, multiplication, and extrusion or
Cell damage could occur through T cell-mediated inflammation, producing microvilli death and Cryptosporidium excess growth
A scanning electron micrograph of Cryptosporidium lining the intestinal tract. (From: Gardiner et al., 1988, An Atlas of
Protozoan Parasites in Animal Tissues, USDA Agriculture Handbook No. 651.)
A scanning electron micrograph of a broken meront of Cryptosporidium showing the merozoites within. (From: Gardiner et al., 1988, An Atlas of Protozon Parasites in Animal Tissues, USDA Agriculture Handbook No. 651.)
Symptoms
Some individuals can be asymptomatic
Incubation period: 2-10 days
Symptoms include:Stomach cramps, pain, watery diarrhea,
dehydration, weight loss, vomiting, fever. Immuno-competent individuals: 1-2 weeks Immuno-compromised individuals: longer
(months, even years!)Patients excreting at least 2-25 liters of watery
diarrhea per day life threatening!
LAB DIAGNOSIS
Microscopic exam Modified acid fast
stain of stool sample
Endoscopic biopsy of small intestine
Cryptosporidium oocysts with acid-fast stain
Cryptosporidium oocysts with acid-fast stain
LAB DIAGNOSIS
Immunodiagnosis Immunofluorescence
assay (IFA) Enzyme linked
immunoabsorbant assay (ELISA)
Polymerase Chain Reaction (PCR) Test of choice
LAB DIAGNOSIS
Treatment
No effective therapy, currently researching for a suitable prophylactic drug.
Immuno-competent individuals will recover with fluid and electrolyte replacement.
Nitazoxande for treatment of diarrhea.
For individuals with AIDS, anti-retroviral therapy will reduce oocyst excretion and decreases diarrhea.
Control Methods
Water purification and filtrationRoutine testingUse of 1 micron filter to remove cystsBoil water
Drink bottled water when traveling abroad
Educate public
Wash hands frequently
Avoid fecal matter during sexual activity
INTERESTING FACT
There were 6 outbreaks between 1984 and 1994 in the US.
Cryptosporidium is resistant to chlorine. Not protected in
chlorinated pool.
In MO there were 26 confirmed cases from motel pools in 1994.
INTERESTING FACT
Cattle alone produce about 4.57 tons of Cryptosporidium oocysts per year in the US
BEWARE !