Quantitative risk assessment of foot-and-mouth disease introduction from Laos to China integrating habitat suitability and cross-border trade analysis.

Laos and its cross-border regions with China remain highly endemic for foot-and-mouth disease (FMD). With the increasing cross-border trade under the Belt and Road Initiative, the risk of FMD virus (FMDV) introduction into China via live cattle trade may have increased; however, integrated quantitative assessments tailored to the China-Laos live-cattle trade interface remain limited. To address the limitations of passive outbreak reporting in endemic settings, this study integrated official outbreak records and literature-derived serological exposure data from 2005 to 2025 to construct a comprehensive risk analysis framework combining maximum entropy (MaxEnt) ecological niche modeling and stochastic scenario tree risk assessment. Monte Carlo simulations were utilized to quantitatively evaluate the risk of viral introduction through legal and illegal trade pathways, as well as the effectiveness of various intervention strategies. The FMD habitat suitability model indicated that predicted suitability was most strongly associated with wind speed seasonality and distance to roads. Approximately 36.2% of the territory in Laos was classified as suitable habitats, characterized by a belt-like distribution along transportation networks. Quantitative assessment identified illegal live-cattle trade as the dominant modeled pathway for potential FMDV introduction events. The mean per-batch probability of a potential FMDV introduction event through the illegal-trade pathway was 0.0679, and the modeled expected annual number of potential FMDV introduction events under the baseline scenario was 61.7. Graded scenario-response analysis showed progressive reductions in the expected annual number of potential FMDV introduction events as annual illegal-entry volume, source infection probability, or transport-stage evasion decreased. In contrast, reducing batch size while holding total annual illegal-entry volume constant increased this endpoint because shipment frequency increased. Increasing destination-herd vaccination coverage and vaccine antibody qualification targets reduced the expected annual number of potential FMDV introduction events, especially when both components were improved jointly. In conclusion, illegal live-cattle trade may represent a major pathway for transboundary FMDV introduction. Future prevention and control strategies should shift from isolated border interception to comprehensive whole-chain risk governance.