Baseline serological assessment of foot-and-mouth disease using a non-structural protein antibody lateral flow assay in cattle from an foot-and-mouth disease-free region of Indonesia

Foot-and-mouth disease (FMD) is a highly contagious transboundary animal disease causing major economic losses worldwide. This study aimed to establish baseline serological data for FMD in cattle from an FMD-free region of Indonesia using a non-structural protein (NSP) antibody lateral flow assay and to evaluate diagnostic interpretation in a low-prevalence setting. A total of 218 serum samples were collected in East Nusa Tenggara Province. Six samples (2.75%) tested positive, 211 (96.79%) were negative, and one was invalid. The apparent prevalence was 2.75% (95% CI: 1.01–5.90%). Adjusted true prevalence using the Rogan–Gladen estimator was 0%, indicating no detectable infection within the study population rather than definitive absence of infection. Considering assay specificity (96.46%), the observed positives are consistent with expected false-positive results. No clinical signs were observed. These findings suggest no evidence of active FMD circulation within the limits of the study and highlight the importance of cautious interpretation of serological data in low-prevalence settings.