Cryptosporidiosis is a disease caused by protozoan parasites of the genus
Cryptosporidium. These parasites primarily infect the epithelial lining of the intestinal tract but may also affect the respiratory system. As a result, the disease can present as either gastrointestinal or respiratory illness. Cryptosporidium infections are typically opportunistic, most commonly affecting young or immunocompromised birds.
In chickens, infection of the bursa of Fabricius (bursal cryptosporidiosis) is often associated with immunosuppressive diseases such as
Infectious Bursal Disease virus or
Chicken Infectious Anemia virus.
Multiple Cryptosporidium species can infect a wide range of animals, including humans. The following species have been reported in chickens:
- Cryptosporidium baileyi: Affects multiple tissues, including the bursa of Fabricius, conjunctiva, kidneys, respiratory tract, cloaca, and rectum. It is found worldwide in many bird species.
- Cryptosporidium meleagridis: Primarily infects the small and large intestines and is found globally in various bird orders.
- Cryptosporidium galli: Targets the proventriculus and has been reported in chickens across Asia, Europe, Oceania, and South America..
- Cryptosporidium andersoni: Reported in chickens and other Galliformes in Europe.
- Cryptosporidium parvum: Infects the small intestine or ceca and is found across multiple bird species worldwide, including in the Americas.
Transmission
Chickens become infected by ingesting
Cryptosporidium oocysts shed in the feces of infected hosts. These hosts may be other chickens or different bird species. Oocysts are highly resistant in the environment and can survive for extended periods—often more than six months—especially in cool, moist conditions such as contaminated water sources.
Diagnosis
Cryptosporidium organisms may be detected in multiple tissues, including the conjunctiva, sinuses, trachea, lungs, kidneys, intestines, cloaca, and bursa of Fabricius.
Treatment
Cryptosporidiosis can be challenging to treat. Management focuses primarily on supporting the bird’s immune system, as infections are most common in immunocompromised individuals. Identifying and addressing any underlying disease is critical.
