Quantitative risk assessment of antimicrobial resistance exposure among farmers through indirect water reuse for irrigation

This study aimed to assess the annual disease burden associated with exposure to antimicrobial resistance (AMR) among farmers through the use of irrigation water contaminated with AMR. The probability of infection, the conventional metric in quantitative microbial risk assessment (QMRA), does not capture disease burdens caused by AMR, such as prolonged treatment and more severe illness. To address this, disability-adjusted life years (DALYs) were applied to estimate additional disease burdens due to AMR for diarrhea caused by <i>Escherichia coli</i> and impetigo caused by <i>Staphylococcus aureus</i>. Lake water used for irrigation was contaminated with sulfamethoxazole/trimethoprim (ST)- and tetracycline (TC)-resistant <i>E. coli</i>, linked to fecal pollution from livestock-related facilities, and amoxicillin (AMX)-resistant <i>E. coli</i>, which was widespread across the lake basin. QMRA revealed that the probabilities of infection from both <i>E. coli</i> and <i>S. aureus</i> exceeded the commonly accepted risk of 10^-4. DALY-based estimates showed that AMR increased the annual disease burden by up to 4.2% compared with a non-AMR scenario, and potentially up to +100% under a high-AMR condition. These findings demonstrate that DALYs effectively quantify AMR-related health burdens associated with irrigation water containing directly or indirectly reused wastewater and support decision-making for AMR risk mitigation.