Flies
The presence of the fly is always an indicator of a proofing defect and possibly a hygiene problem. The term “flying insects” can encompass almost all insects in some stage of their life cycle. In the food industry, it is generally accepted that those which are regarded as pests are those which spread disease through contamination, cause physical damage and cause a general nuisance.
There are many thousands of species of flies; however, relatively few interact with humans. Those that do are among the most destructive of pest species, spreading disease to man and domesticated animals, as well as contaminating food.
The fact that adult flies can fly makes their status as pests so important, allowing them mobility to visit many diverse habitats. By nature, many flies breed and feed in areas of unsanitary conditions, with larvae feeding on decaying organic matter.
The adult female uses complex sensory systems to choose suitable areas of rotting vegetation and decaying animal matter in which to lay her eggs and for the larval stages to develop into pupae.
The adults emerge from the pupae in these unsavoury sites and, as they do, they become contaminated. Often, they will move into sensitive food preparation, processing and consumption areas, seeking feeding sites for themselves as adults.
When an adult fly feeds on infected decomposing matter, for example human faeces containing excremental disease organisms, pathogens will be taken up into the gut via the mouthparts. Organisms will stick to the hairs of the legs and body and cling to the minute bristles on the footpads as the fly walks over the faeces. Having taken a meal from this source, the insect may fly into a kitchen, dining room or restaurant, land on food which is left unprotected and go through the same process of feeding. It will walk over food, cleaning the legs and body and depositing disease organisms as it moves. It will vomit fluid containing organisms from the previous meal in order to liquefy its present food source, and at the same time it will defecate the remains of previous meals of infected material.
Organisms carried in this way include those causing typhoid, paratyphoid, amoebic and bacillary dysentery and cholera, as well as other forms of gastroenteritis. It may also transmit eggs of certain worms that will infect the human alimentary canal.
The likelihood of contamination of human food with pathogens has been proven over the years by a number of experiments. In these, disease-causing agents have been found to survive on outside body surfaces of flies, particularly among the hairs. They also exist in the gut and blood system. Some of the types of disease-causing organisms referred to as Salmonella and Campylobacter.
When the food on which the flies are feeding has been prepared for human consumption, human disease and suffering can result. Food poisoning outbreaks can occur from a minute dose of pathogens and it is more than likely that, in these cases, flying insects have spread the disease.
The US Council for Agricultural Science and Technology (CAST), in its report on the risks of food borne pathogens, recommends that control principles including HACCP should be applied from food source to consumption to reduce the likelihood of food borne illness.
From a regulatory perspective, disease-carrying flies present a unique challenge.
The European Directive on Food Hygiene (EC Directive 93/43) lays down that member states’ legislation must include clauses such as the following:
“The layout, design, construction and size of food premises shall permit good food hygiene practices, including protection against cross contamination between and during operations, by foodstuffs, equipment, materials, water, air supply or personnel and external sources of contamination such as pests: and …” (Regulation 4 (2) (a), Schedule I, Chapter I)
“All food which is handled, stored, packaged, displayed and transported shall be protected against any contamination likely to render the food unfit for human consumption, injurious to health or contaminated in such a way that it would be unreasonable to expect it to be consumed in that state. In particular, food must be so placed and/or protected as to minimise any risk of contamination. Adequate procedures must be in place to ensure pests are controlled.” (Regulation 4 (2) (d), Schedule I, Chapter IX)
Member states have now introduced regulations implementing the above.
In the food industry, hygiene is of utmost importance. Basic regular cleaning and disinfecting is fundamentally important in reducing the number of potential fly breeding sites and therefore reduce the risk of build-up of disease-causing micro-organisms.
HTW has noted that amongst the submissions to the Committee on Toxicity (COT) it has been suggested that the symptoms highlighted by crew and passengers were akin to the condition of hyperventilation.
HTW has for many years received reports from concerned holiday makers or independent travellers as to the safety of their aircraft, ship or boat, train or road transport.
