University of Sulaimani School of Science Department of Biology Practical Parasitology 2 nd stage Lab 10: Cryptosporidiosis Enteric Apicomplexa: Cryptosporidium parvum
Objectives: Students should be able to:
Identify oocyst stage in a stool smear.
Describe trophozoite, sporozoite, and oocyst stages of C. parvum.
List methodes of transmission and diagnosis.
Cryptosporidium parvum is another apicomplexan parasite
It is an enteric, anthroponotic and zoonotic parasite
One of the three most common diarrhea-causing pathogens in the world.
One of the most common causes of waterborne illness in the world.
Causes a self-limiting diarrhea in immunocompetent individuals.
Definitive Host: Human
Reservoir Hosts: kittens, puppies, goats, calves, mice, …. Etc.
Disease: Cryptosporidiosis .
Habitat: Epithelial cells of the gastrointestinal tract, mainly jejunum
Transmission: Fecal-oral route.
Food and water
contamination of drinking water
untreated groundwater or well water
an infected person or an asymptomatic carrier contaminates a food supply
Person-person (anthroponosis) transmission
occurs at a high frequency in day-care centers.
Trophozoites are round or oval intracellular, but exocytoplasmic forms
have a single prominant nucleus
Measure 2.0 to 2.5 µm in diameter.
They are transitional stages from sporozoites and merozoites to meronts
Sporozoites Cryptosporidium parvum
Sporozoites are generally crescent or bow shaped,
with the anterior end slightly pointed and the posterior end rounded.
Measure 4.9 by 1.2 µm
Each sporozoite contains a prominent nucleus in the posterior third of the body.
Oocysts are double walled, rounded or ovoid and measure 5 to 6 µm in diameter.
Contain bow-shaped 4 sporozoites, are sometimes visible inside the oocysts, indicating that sporulation has occurred.
sporozoite release from the C oocyst
Life cycle: Cryptosporidium parvum
rounded SEM of type 1 meront SEM of type 2 meront
Mouse small intestine infected with Cryptosporidium parvum . Small bodies seem to be on the surface of epithelial cells are various developmental stages of C. parvum enveloped by host cell membrane. H & E stain.
TEM of Immature oocyst of C. parvum . TEM of Merozoites of C. parvum. SEM of oocysts of C. parvum .
TEM: Meront stage of Cryptosporidium parvum under asexual division (endopolygeny). TEM: Mature type I meront including eight merozoites.
Nausea, Vomiting , Abdominal cramps, and Low-grade fever
For immunocompromised persons, the illness is more severe:
Debilitating, cholera-like diarrhea (up to 20 liters/day), electrolyte imbalance, dehydration and sometimes death.
Severe abdominal cramps, Malaise, Low-grade fever, Anorexia and Weight loss.
Microscopy with an acid fast stained stool smear, which will stain the oocysts bright red.
Another form of microscopy is fluorescent microscopy using monoclonal antibody to oocyst wall
acid-fast oocyst stain Direct immunofluorescence antibody stain
Enzyme immunoassay (ELISA), for the detection of cryptosporidial antigens in stool samples, . has greatest sensitivity and specificity
Molecular methods using PCR
Diagnosis Lane S: Molecular base pair standard (100-bp ladder). Black arrows show the size of standard bands. Lane 1: C. parvum positive fecal specimen. The red arrow shows the diagnostic band for Cryptosporidium parvum zoonotic genotype (size: 435 bp). Cryptosporidium parvum
Chiodini PL, Moody AD, & Manser DW. (Atlas of Medical Helminthology and Protozoology. 4 th ed. Churchill Livingstone, Edinburg.
Smith HV, Cacciò SM, Cook N, Nichols RA, Tait A. (2007). Cryptosporidium and Giardia as foodborne zoonoses. Vet Parasitol. 149(1-2):29-40.