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Cryptosporidiosis is a parasitic disease caused by coccidian protozoan of the genus Cryptosporidium. The infection manifests as a respiratory, urinary tract, and gastrointestinal disease, depending on how the organism gained access into the bird. The three main species that affect poultry include: C. baileyi, C. galli and C. meleagridis. They have been reported in a variety of different avian species, such as chickens, turkeys, quail, and finches. Interaction of C. baileyi with other pathogens present in the chicken's respiratory system often results in secondary infection with E. coli. If chickens become concurrently infected with infectious bronchitis virus (IBV) it can increase the severity of respiratory disease in chickens induced by C. baileyi.

Chicken become infected with Cryptosporidium through ingestion or inhalation of sporulated oocysts, shed in the feces of infected birds. Fecal-oral route and water-associated contamination are thought to be the most likely route of infection in backyard chickens. Oocysts are capable of surviving outside the chicken for long periods of time (often greater than 6 months duration) in cool, moist environments, and on fomites such as farm equipment, buildings, and human clothing.

Clinical Signs

Weight loss
Ruffled feathers
Nasal and eye discharge
Swollen sinuses
Difficulty breathing
Extending neck
Reluctance to move
Increased respiratory sounds (rales)
Undigested food in droppings


  • Cytology
  • Fecal test
  • Acid-fast staining
  • Direct fluorescent antibody [DFA]


Supportive careIsolate the bird from the flock and place in a safe, comfortable, warm location (your own chicken "intensive care unit") with easy access to water and food. Limit stress. Call your veterinarian.
Paramomycin100 mg/kg administered orally every 12 hoursK Marx



Good sanitary practices

Scientific References

Risk Factors

  • Keeping birds in a dirty, unsanitary environment, full of droppings