Kinetics of serum antibody responses in broiler chicks against Cryptosporidium baileyi

The kinetics of serum antibody responses in broiler chickens against Cryptosporidium baileyi were studied. Broilers were inoculated intratracheally with 250,000 C. baileyi oocysts at 1, 7, or 14 days of age. Antibody was quantified by an enzyme linked immunosorbent assay. Anti-cryptosporidial serum immunoglobulins (IgM and IgG) were detected 9 days post-inoculation (DPI) in birds inoculated at 1 or 7 days of age with oocysts and 4 DPI when 14-day-old birds were inoculated. Results also reaffirmed age related susceptibility, with day-old birds being more susceptible than 7-day, and 14-day-old birds were not susceptible to clinical disease. The susceptibility to infection correlated with the amount and duration of the IgM response. Day-old inoculated birds developed a higher, longer-lasting response than 7 or 14-day-old infected birds.