# Risk Assessment of Brucella Exposure Through Raw Milk Consumption in India: One Health Implications and Control Strategies

## TL;DR

Drinking raw milk in India poses a high risk of Brucella infection, and controlling the disease requires a One Health approach combining animal and public health measures.

## Contribution

Quantified the risk of Brucella exposure from raw milk in Punjab, India, and identified high-shedding animals as a key factor.

## Key findings

- Raw milk from unregulated sources in Punjab likely contains over 1000 CFU/100 mL of Brucella abortus.
- Buffalo milk had higher contamination levels than cattle milk.
- Removing high-shedding animals reduces risk but does not eliminate it for regular raw milk consumers.

## Abstract

Brucellosis is a serious veterinary and public health concern in India. Given that drinking milk is an important transmission risk for brucellosis in people, we investigated the risk of Brucella abortus exposure from milk sold via the unregulated supply chain in Punjab, India, to identify the influential factors that could be targeted by control measures. We estimated that even 100 mL of raw milk from unregulated sources is likely to contain Brucella abortus colony-forming units that exceed 1000 CFU/100 mL, presenting an alarming public health risk from a single meal of 100 mL unpasteurized milk. High-shedding animals were found to have most influence on risk, and whilst their removal could reduce the risk on a single occasion, consumption of 100 mL with as low of a frequency as once monthly posed a considerable risk. It is clear, therefore, that without the elimination of B. abortus in cattle, an ongoing One Health approach incorporating consumer education with regard to boiling milk, improved regulation of milk sales, and animal health measures (vaccination of cattle, and identification and removal of high shedders) are required. These measures are also not without considerable challenges, highlighting that without strong advocacy, brucellosis will remain a neglected disease of vulnerable people.

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.