Serological tests detect antibodies in blood serum using specific antigens. In food safety they help diagnose infections linked to foodborne pathogens and verify immune responses in livestock. The antibody-antigen reaction gives a measurable signal, making serology a practical tool for herd health monitoring and outbreak investigation. Results guide vaccination and control programmes. They connect animal health with food safety, and surveillance programmes rely on them for early detection of problems. The antibody-antigen reaction gives a measurable signal, making serology practical for herd health monitoring and outbreak investigation.