The journey of the germ in food processing and preparation

The World Health Organisation (WHO) has described food contamination and food-borne diseases as an increasingly global threat to the health and wellbeing of millions of people every year. As a matter of fact, the WHO revealed that 600 million people globally are affected by food-borne diseases every year.

The level of threat growing on a global scale could be due to a number of social and economic reasons. The reason for this is because growing international trade in food and food handlers travelling between countries are having a massive impact, but reported outbreaks and cases have found that common contributory causes to foodborne illnesses include cross-contamination, improper cooking temperatures of foods and poor employee health and hygiene.

Data also found by WHO found that anything from 20-40% of cases is thought to be acquired from home, however, the majority of cases are acquired from food consumed outside the home. In actual fact, “eating out” has been related to an increase in consumers self-reporting that they have experienced a food-borne disease. So, how and why do pathogens spread and what role does cross-contamination play as a risk factor in food-borne disease?

The rise and rise of cross-contamination

Cross-contamination describes the ways in which microorganisms can spread within a food handling/ processing environment. It is considered as a common risk factor in outbreaks of food-borne disease – according to a study in the 1970s, in the UK, cross-contamination was typically reported in only 5-7% of outbreaks. By the early 2000s, this grew to 39%.

A US inspection study found that poor personal hygiene and hand hygiene are major components of cross-contamination. The types of foods reported in outbreaks could also contribute to a higher number of cases being recorded. Today, cross-contamination cases occur within breakfast cereals, peanut butter, nuts, chocolate, and increasingly with “leafy greens” or fresh fruit and vegetables.

Common pathogens and the dangers of poor hygiene practice

Pathogens that can go on to cause food-borne diseases can stem from a number of sources in food processing that can then be spread by cross-contamination, such as from people, unclean equipment and raw materials. Below are three common pathogens and the possible consequences of not implementing measures to guard against cross-contamination:

• Norovirus: Research has found Norovirus to be one of the main causes of gastroenteritis worldwide and is responsible for 90% of viral gastroenteritis. Cross-contamination (direct or indirect) is likely to be an important element in most cases. This because norovirus, when shed in large quantities via diarrhoea and vomit, survives well on various surfaces. A study conducted in London and the South West of the UK of the role of food handlers in norovirus outbreaks recommended to improve hand hygiene practices and educate food handlers about the risks they pose when working symptomatically and asymptomatically.
• Campylobacter: Campylobacter is the most common cause of bacterial stomach upsets. The bacteria are found as contaminants in a range of foods, especially raw poultry such as chicken. Handling raw poultry can also lead to direct and indirect cross-contamination of surfaces and foods, for example, food handlers may wash their hands after handling raw chicken but many don’t wash their hands after touching poultry packaging.
• L.monocytogenes (Lm):  L.monocytogenes has excellent survival abilities, is capable of growth at low temperatures, is widely found in food environments and can be difficult to eradicate. As such refrigerated foods must have a low L.monocytogenes count at the end of their shelf life (typically less than 100cfu/g). Preventing cross-contamination of foods during processing or retailing including hand hygiene and cleaning have also been identified as key outbreak control measures.

Factors contributing to the risk of cross-contamination

Avoiding cross-contamination is one of the more complex and multifaceted food hygiene control measures. Important factors that help the prevention of cross-contamination include disinfecting surfaces and washing/drying hands correctly. Businesses should develop a positive hand hygiene and cross-contamination prevention culture as part of its food safety management system. By implementing this programme, it will ensure the control measures are understood and valued.

There are a variety of factors that can increase or decrease the risk of cross-contamination spreading pathogens. Surface contamination levels, dirty clothes and cleaning equipment are risk factors, and cleaning surfaces effectively and using gloves and utensils correctly decreases the risk of cross-contamination.

• Hands, hand hygiene and hand microbiology: Food handlers have been associated as a serious risk factor in the spread of food-borne disease when they do not implement practises that can prevent cross-contamination. Humans can be a source of micro-organisms and at any given time can host 1012 organisms on their skin, 1010 in their mouth and 1014 in their gut. Micro-organisms adapt to human hands as they attach and survive well on human skin. For example, Staphylococcus aureus is frequently part of the hand’s normal bacterial flora. However, if it gains access to poorly temperature-controlled food that supports its growth, it can produce toxins in that food leading to severe illnesses.
• Surfaces and surface cleanliness: Molecular tracking techniques underline a close link between hand contaminants, cleaning, cleaning equipment and other surfaces the equipment may touch. Hands or utensils that come in to contact with contaminated surfaces have greater potential to spread and transfer pathogens.

Cleaning management

Surfaces and equipment can only be successfully cleaned if they are designed, constructed and maintained appropriately. A study using molecular identification techniques demonstrated that the same organisms that had been isolated from foods could also be isolated from cleaning equipment that has not been decontaminated and stored properly. For example, dirty dishcloths are known to be heavily contaminated.

Cleaning programmes should be validated and verified to prove that they work and are being used correctly. They should also include not only food contact surfaces but also hand contact surfaces such as handles on fridges, cupboards and door handles.

Personal and hand hygiene practices

Food handler personal hygiene is essential in preventing the spread of germs within food premises and to food. Personal hygiene is an important aspect of this, ensuring the individual food handler does not spread germs. It is effective management to establish and then maintain a positive general, personal and hand hygiene culture. Maintaining a successful hand hygiene culture begins with having a strong understanding of hygiene principles and emphasises the importance of hygiene training. Food handlers need to understand the business’s personal hygiene policies and requirements, such as not working when ill.

Hand hygiene is also a particular focus and management has a big role to play here, as they have a responsibility to provide adequate facilities for hand decontamination such as no-touch soap dispensers and paper towels. In addition, businesses should have a well-constructed hand hygiene policy which should include some of the following: food handler health, hand hygiene and hand habits, and a glove policy.