2. History and Distribution
• First observed in the gastric mucosal
crypts of laboratory mice Tyzzer in 1907.
• Causes diarrhea in humans and animals
• Frequent cause of intractable diarrhea in
AIDS patients and immunocompromised
subjects
• Worldwide distribution
• C.parvum and C.hominis causes human
infections
4. Morphology
• Infective form- oocyst
• Spherical, oval, 5µm in
diameter
• Does not stain with iodine
and is acid fast
• Thick walled but 20%thin
walled- autoinfection
• 4 crescent shaped
sporozoites
• Very hard and resistant.
Temperature-60ºC
• Sequential application of
ozone and chlorine –
eliminate cyst
5. Life Cycle
• Monoxenous
• Suitable host- man
• Reservoirs-man, cattle, cat, dog
• Mode of transmission:
– Ingestion of contaminated food and water
– Autoinfection
• Infective form-Oocyst
6.
7. Pathogenicity
• Humans get infection by:
– Ingestion of contaminated food and water
with feces
– Direct contact with infected animals
– Human to human transmission
• Incubation period 2-14 days
8. Clinical features
• Immunocompetant person
– Asymptomatic or self limiting febrile illness
– Watery diarrhea, abdominal pain, nausea, weight loss
– Childhood and travelers diarrhea
• Immunocompromised person
– AIDS and CD4+Tcell counts<100/µL
– Chronic, persistent profuse diarrhea. Significant fluid
and electrolyte depletion
– Weight loss, emaciation, abdominal pain
– Stool volume:1-25 L/day
– Billiary tract involvement-right upper quadrant pain,
sclerosing cholengtis or cholecystitis
10. Stool examination
• Diagnosis is made by demonstration of oocystes
in feces
• Direct wet mount- colorless spherical oocyst,4-
5µm containing large and small granules
• Modified acid fast stain-oocyst appears as red
acid fast spheres
• Sheathes sugar floatation test and zinc sulfate
floatation technique
• Florescent staining with aluminum phenol or
acridine orange
• Indirect immunoflurescence microscopy using
specific antibody
14. Treatment
• Nitazomamide or parmomycin – partially
effective
• Antiretroviral therapy can lead to
amelioration of cryptosporidiosis.
• Supportive therapy wit fluid,
electrolytes and nutrient replacement
15. Briefing…
• Sexual and asexual cycles in single host
• Infective form- sporulated oocyst in food and
water
• Clinical feature-self limited diarrhea with
abdominal pain in healthy persons. Chronic
persistent watery diarrhea in immunocompromised
hosts
• Diagnosis-demonstration of round oocyst in stool by
direct microscopy, fluroscent microscopy and
modified acid-fast stain
• Treatment- supportive therapy with electrolytes
and fluids and early antiretroviral therapy in AIDS
patients
