Resistance of Convalescent Chickens to Reinfection with Leucocytozoon caulleryi

Abstract

Chickens infected with Leucocytozoon caulleryi were administered with sulfamonomethoxine (SMM) over a period from some time between 1 and 11 days to 21 days after infection (a. i.). Serum antigen (SA), antibody against SA, and antibody against gametocytes (G) were detected in groups in which medication was started 6 or 7 days a. i. Parasitemia and death were observed in groups in which medication was initiated 10 or 11 days a. i.
When chickens were reinfected 30 days after first infection, SA was detected in groups medicated 1 or 2 days a. i. Parasitemia was observed in groups medicated some time between 1 and 4 days a. i. Clinical signs were observed in groups medicated 1 or 2 days a. i. and accompanied with no death.
Antibodies against SA and G became positive or increased again in titer in all the groups 14 days after reinfection, except in groups medicated 1 or 2 days a. i. in which antibody against SA did not.
These results suggest that the 2nd generation schizont may play an important role in causing a resistance to reinfection in chickens recovered from infection with L. caulleryi, and that the 1st and 2nd generation merozoite and gametocyte may have partly common antigen.