Interventions Were Designed to Be Appropriate for Studied Facilities

The researchers evaluated the effects of two interventions on hygiene practices and microbial contamination at 16 pig slaughterhouses across four Vietnamese provinces from May–December 2024.

1. The “Technique” intervention involved approximately $1,000 in low-cost equipment upgrades, such as elevated stainless-steel slaughtering surfaces and cleaning supplies, alongside hygiene training and educational posters
2. The "Incentive" intervention involved audio reminders to wash hands and clean tools, as well as a hygiene-practice rating program that rewarded workers with approximately $7.60 USD ($200,000 VND) for demonstrating satisfactory hygiene practices.

Slaughterhouses received either Technique-only interventions, Incentive-only interventions, both interventions, or neither intervention.

Both interventions were developed within a context-appropriate framework for low-resource slaughterhouses and built on a pilot previously implemented in northern Vietnam. Their content was adapted from training and communication materials produced by ILRI’s SafePORK project, which ran from 2017–2022 to develop and evaluate light-touch, market-based approaches to improving food safety in the Vietnamese pork sector, and were reviewed for cultural and operational appropriateness by local animal health officers.

Researchers collected 192 pig carcass swabs and 128 workers' hand swabs before and after the interventions, testing for total bacterial counts, coliforms, and Escherichia coli. Carcass samples were also tested for Salmonella.

Hygiene Improvements Did Not Reduce Microbial Contamination

Overall, Salmonella prevalence on pig carcasses remained largely unchanged, from 37.5 percent at baseline to 35.4 percent after the interventions.

Mean total bacterial counts decreased from 5.4 to 4.7 log₁₀ colony forming units per square centimeter (CFU/cm²), while coliform and E. coli counts also declined. However, reductions in bacterial contamination occurred within intervention and control groups, which the researchers said is a pattern more consistent with seasonal and operational factors rather than the result of interventions.

Although the Technique intervention significantly improved hygiene practices, the Incentive intervention produced only short-term improvements during the reward program. Still, neither intervention was associated with reduced carcass contamination.

Absent Hygiene Practices, Other Observations

Importantly, several critical hygiene practices remained absent throughout the study. Workers were not observed washing their hands or boots with soap during baseline or follow-up assessments, and improvements were primarily limited to water-based washing.

The researchers also identified associations between microbial contamination and operational or environmental factors, including ambient temperature, workforce size, and slaughtering capacity.

Researchers Call for Comprehensive Slaughterhouse Hygiene Improvements

Overall, the findings suggested that improving workers' hygiene practices alone may be insufficient to reduce microbial contamination in traditional slaughterhouse settings.

The researchers concluded that effective contamination control requires sustained, multi-level interventions combining infrastructure and operational improvements with targeted worker hygiene measures, particularly soap-based cleaning, to address foodborne microbial hazards.