Abstract
Background:
Leucocytozoonosis, caused by Leucocytozoon caulleryi, is a significant parasitic disease in poultry and can cause substantial economic losses in the broiler chicken industry while the gloden standard of examination is currently absent.

Aim:
This study aimed to detect the presence of L. caulleryi in broiler chickens in East Java Province using two different diagnostic methods.

Method:
Blood samples were taken from the brachial vein of death broiler chickens from several farms recorded as endemic areas of lecucytozoonosis in East Java, Indonesia. Parasite detection was performed using parasitological examination (blood smear) and ELISA serological examination methods.

Result:
The results showed a prevalence of L. caulleryi of 13.43% based on blood smear examination, while ELISA serological examination showed a higher prevalence of 27.78%. This difference in results indicates that serological tests have a higher sensitivity in detecting L. caulleryi infections compared to parasitological methods.

Conclusion:
These findings emphasize the importance of using appropriate diagnostic methods in efforts to control leucocytozoonosis in broiler chicken farms. Furthermore, the results of this study can serve as a basis for developing more effective control strategies against this disease in East Java Province.

Key words: Blood smear, Broiler chickens, ELISA, Leucocytozoon caulleryi, Prevalence