Abstract
Brucellosis is a zoonotic disease with significant public health implications. Understanding the risks of consuming unpasteurized (raw) milk is critical for effective control measures. A quantitative risk assessment was conducted to estimate Brucella abortus contamination in milk from unregulated sources in Punjab, India, where 70% of milk is sold unpasteurized. Samples from lactating cattle and buffalo (N = 261) in ten villages were tested using the Rose Bengal plate test and indirect IgG ELISA. Modelled risk pathways estimated B. abortus shedding probabilities and colony-forming unit (CFU) concentrations in milk, with Sobol sensitivity analysis identifying influential parameters. Buffalo had a higher estimated shedding prevalence (0.04, 95% PI: 0.02-0.07) than cattle (6.3 × 10(-3), 95% PI: 2.5 × 10(-3)-13.2 × 10(-3)). Mean contamination levels were 2843 CFU/100 mL (95% PI: 0-32,693 CFU/100 mL) for cattle, 17,963 CFU/100 mL (95% PI: 612-67,121 CFU/100 mL) for buffalo, and 7587 CFU/100 mL (95% PI: 82-39,038 CFU/100 mL) combined. High-shedding animals were the most influential factor (total effect sensitivity index of 0.86 [95% CI: 0.63-0.74]). Removing high-shedding animals reduced risk considerably for people who might drink raw milk once (absolute risk reduction of up to 54% in buffalo milk), but once-per-month consumption is still likely high risk. Effective risk mitigation requires a One Health approach, strengthening both public and animal health interventions, because animal health strategies alone will fail if milk from high-shedding animals reaches the unregulated milk market.