Equipment Cleaning

• Fomites are inanimate objects that, when contaminated, can carry and spread infectious microbes.
• In agricultural contexts, typical fomites include ropes, dust, tractors, crop leaves, workers’ boots, knives, transport crates, and field gates.
• Equipment such as tractors that have come into contact with livestock or manure should not be used in the harvesting of ready-to-eat crops without thorough cleaning. Ideally, contamination should be prevented altogether through careful equipment storage and handling.
• Where cleaning is required, validated sanitisers should be used to ensure the effective removal of pathogens.

Most foodborne illness pathogens associated with fresh produce are transmitted via faecal contamination. This contamination can occur directly, for example, through contact with manure from livestock, or indirectly, via contact with contaminated equipment.

The term fomite refers to any inanimate object capable of transmitting infectious agents when contaminated. In agricultural settings, fomites can include a wide variety of everyday tools and materials - ranging from ropes and dust to tractors, crop leaves, workers’ boots, knives, transport crates, and field gates (1-4). Once contaminated, these items can further transmit pathogens to anyone or anything that comes into contact with them.

The risks posed by manure-contaminated equipment, particularly tractors and other harvesting machinery, are difficult to measure precisely, as not all manure contains pathogens harmful to humans. There is limited published research quantifying the likelihood of pathogen transfer via fomites during food crop production (5).

However, it is widely accepted that using a tractor which has recently passed through a livestock field, and may therefore carry faecal matter, is not safe practice before harvesting ready-to-eat crops. Likewise, most growers acknowledge the importance of cleaning harvesting equipment before use. The most effective approach is to prevent equipment contamination altogether, by storing tools away from livestock areas and known sources of manure (5).

Validated disinfection protocols are now available for smaller tools such as knives (6), and some harvesting tools have even been redesigned to be more hygienic (7).

Several studies have highlighted specific examples of equipment-related contamination. Knives and food processing machinery used post-harvest could act as fomites, contaminating fresh-cut produce (8). Pathogens are known to survive on surfaces for extended periods; Salmonella Typhimurium, for example, has been recovered from stainless steel surfaces hours after initial contamination (9).

The significance of contaminated equipment was further demonstrated by an outbreak involving 41 cases of Salmonella Bovismorbificans, which was traced back to a cutting wheel used on a lettuce shredder (10). These findings reinforce the need for proper cleaning and sanitisation of any equipment that comes into contact with the edible portions of crops – especially where crops will be eaten raw, such as salads and herbs.

In conclusion, all tools and equipment used during harvest should be:

I.    Cleaned regularly following a formal, documented procedure

II.    Sanitised with validated agents

III.    Stored to prevent cross-contamination

Cleaning protocols and recommended food-grade sanitisers can be obtained from professional cleaning supply companies. It is also considered best practice to validate cleaning and sanitisation procedures, ensuring that microbial risks are effectively controlled.