Serological Detection of O-Type and A-Type Antibodies Against Foot-and-Mouth Disease in Tongliao City, 2021-2022.

Foot-and-mouth disease (FMD) is an acute, febrile, and highly contagious viral disease caused by the foot-and-mouth disease virus (FMDV). Serological testing for FMDV antibodies is an effective method to assess the immune response following vaccination. In this study, 36,510 bovine blood samples were collected from both households and farms across 8 districts of Tongliao City, Inner Mongolia Autonomous Region, China, between January 2021 and December 2022. Enzyme-linked immunosorbent assay (ELISA) was employed to detect serum antibodies. The results indicated that the seropositivity rates of O-type FMDV antibodies in eight regions (A-H) of Tongliao City during 2021-2022 ranged from 73.09% to 100% in 2021 and 83.75%-100% in 2022, respectively. Significant differences were observed among the regions. In 2021, the immune protection levels of A-type FMDV antibodies in Regions B and G were below 70%, at 65.38% and 68.40%, respectively. In 2021, the positive rates of FMDV O-type and A-type antibodies were significantly higher (p < 0.05) on farms compared to households, indicating a higher trend in farms. However, in 2022, no significant difference was observed between farms and households (p > 0.05). Seasonally, the positive rates of O-type and A-type FMDV antibodies in spring, summer, autumn, and winter of 2021 were 80.81%-97.67% and 78.27%-94.07%, respectively, while in 2022, they were 83.18%-96.50% and 80.14%-94.76%, respectively. During the period from 2021 to 2022, FMD immunization efforts in various regions of Tongliao City achieved generally satisfactory immunization outcomes. However, Regions B and G require enhanced immunization and reevaluation. This information serves as a valuable reference for the formulation of prevention and control strategies for FMD Serotypes O and A.