Family: Cryptosporididae
Genus: Cryptosporidium spp.
• Cryptosporidiosis is a disease cause by Cryptosporidium spp. Principally an
intestinal protozoan parasite, It is worldwide in distribution infect wide range of
hosts like mammals (including man), birds, reptiles, fishes & amphibian; highly
significant to veterinary medicine and public health.
• More than (20) species belong to the genus Cryptosporidium have been recorded;
most important species are C. parvum of mammals (involving humans), C. muris
of rodents and possibly cattle, C. andersoni of cattle, C. baileyi and C. meleagridis
of chickens and turkeys.
• Oocysts which pass with feces & not develop outside the host have oval to
spherical shape, range in size from 5.0×4.5 to 7×6; it contains four crescent
shaped sporozoites .
Epidemiology:
• Mode of transmission is fecal- oral route by ingestion of contaminated food &
water with Oocysts.
• The newly born and young animals more susceptible to infection & with more
severe symptoms than adults.
• Mice , rats and other rodents considered an animal reservoir .
• Insects such as flies play important role in transmission of parasite.
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• Cryptosporidium spp. have very short life cycle (not exceed than 72 hours)
which participate in distribution of infection, more over it have small infective
dose (ingestion of 10 Oocysts enough to induce infection).
• The Oocysts have highly innate resistant to the chemicals & it also resist water
sterilization by chlorine, to kill the parasite in the drinking water we must use other
methods like heating, filtration and by Ozone. However, the greatest results
obtained by sterilization with radiation.
Life Cycle:
• Direct.
•After ingestion, sporozoites will release from Oocyst and invade microvillous
border of lower half of the small intestine lie in a vacuole just beneath the host cell
membrane (intracellular but extracytoplasmic); undergo two or three schizont
generations, followed by sexual development and oocyst production within 72
hours; oocysts sporulate before leaving the cells and pass in the feces.
• Prepatent period can be as short as 3 days.
• Oocysts are extremely resistant to environmental conditions and most man-made
chemicals.
Pathogenesis and Clinical Signs:
• parasite present in the epithelial cells of gastrointestinal tract particularly ileum;
cause change in the shape and then death of infected cells leads to sloughing
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epithelium, it also cause changes in osmotic pressure of these cells ; these changes
then cause the characteristic severe, watery diarrhea.
• The disease usually self-limiting, lasting 1–3 weeks in; lesions are mild to
moderate; severity of disease is exacerbated in the presence of other pathogens
(e.g., rotavirus in calves).
Diagnosis:
1- Detection methods include:
Direct normal saline smear: can be air dried and
stained modified Zheil-Nelson stain.
ELISA test: several test kits commercially
available for humans; may be useful in other
mammals;
Immunofluorescence test:
2- We can find developmental stages on histological section in microvillous
border of affected tissue.
Treatment and Control:
• Paromomycin has been shown capable of preventing clinical signs and mortality
and decreasing oocysts output in calves, kids, and cats.
• Control is difficult; strict sanitation is needed; separation of susceptible animals
from dams may be required including separate personnel to care for each.
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