5,16,20,21) These studies demonstrated that the prevalence of caryosporiosis may vary from 12% to 86%.
5,16,20) In juvenile raptors, such as merlins (Falco columbarius) (2) and Eurasian kestrels, (21) clinical caryosporiosis is characterized by severe diarrhea (7) or acute death in young chicks aged between 28 to 45 days, (3,22) although they do not show clinical signs until 27 days old, even if exposed earlier to the caryosporan oocysts.
Caryosporiosis is difficult to control because of the lack of immunity in young birds and the persistence of infective oocysts in the environment.
The significance of caryosporiosis in captive falcons is great, (8) and it considered one of the most important causes of morbidity in captive raptors, with a high mortality, particularly in small falcons, such as merlins.
Caryosporiosis may have a considerably higher effect in captive-bred falcons and less importance in free-living birds because of the confined space of aviaries.
Previously identified factors that influence the prevalence in surveys of caryosporiosis are the source of the birds, the level of infection of the breeder falcons, and the age of birds.