Decontamination is a combination of physical and chemical processes that kill or reduce the load of microbes present on the farm at the end of a production cycle or after a disease outbreak. In the Australian poultry industry, decontamination is normally performed after the end of each production cycle to prevent the spread of disease-causing organisms between old and new batches of birds. These include poultry-specific pathogens and foodborne pathogens present on the farm.

Decontamination reduces the intensity and frequency of emergency animal diseases (EADs), notifiable diseases, and foodborne illnesses. The Australian poultry industry has had numerous encounters with EADs, such as highly pathogenic avian influenza, Newcastle disease, and highly virulent infectious bursal disease. These diseases have the potential to cause high mortality among birds. EADs can also lead to the closure of farms, trade restrictions, job losses and other indirect adverse effects such as consumers’ hesitation to consume poultry products. Furthermore, management and eradication of these diseases are complex and expensive. Hence effective decontamination is essential in preventing these diseases on farms.

An ideal decontamination protocol involves appropriate cleaning and disinfection steps. Following the correct cleaning principles will help achieve better decontamination results. These principles include:

Time – the duration of the cleaning process plays an integral part in effectively decontaminating a premises. Thorough decontamination requires sufficient time to effectively remove litter and organic matter from all surfaces within the shed. In addition, the cleaning chemicals must have adequate contact time with the surfaces being cleaned. The contact time depends on the properties of the cleaning chemicals; the method of application; the ambient temperature and humidity; and the ability of the chemicals to penetrate the soils, wet out surfaces of the structures being cleaned and suspend the soil in solution in preparation for being rinsed off.

Temperature – the cleaning chemical must be used at its optimum temperature as indicated by the manufacturer to maximise its effectiveness. Care should be taken to understand the effects of optimal temperature on the structures being washed.

Agitation – agitation helps the washing solution penetrate soils, and should cover all the surfaces that need to be cleaned. Some examples include hand scrubbing, high-pressure water spraying and mechanical brushing.

Cleaning chemicals – the chemical(s) selected must consider the following:

• The target organism – the chemical(s) need to be selected based on their mechanism of action on the target organism.
• The properties of the surfaces being cleaned – porous or non-porous; reactive or non-reactive.
• The types of soils (e.g. protein, fat) being removed, requiring that all soils are held in solution and easily rinsed off.
• The environment in which the washing is being carried out – enclosed or open.
• The application method of the solution.
• The final disposal of the solution

Water that will be used to make the working solution of the chemical must be potable without any pathogenic microorganisms and organic matter. Suitable levels of minerals must be considered, along with the pH (level of acidity or alkalinity). Some minerals and their pH may interfere with the activity of the chemical. Therefore, regular water quality tests should be carried out on all water sources to ensure compatibility with the chemical selected.

Chemical concentration – the concentration of the active chemical must be at an effective level at the surface of the structure that is being cleaned and sanitised. This allows a sufficient period for the chemical to carry out its activity at the operating temperature. The chemical manufacturer should have recommendations relating to concentration, and these may vary depending on the amount and types of soils present, the nature of the surface being cleaned and the environmental temperatures.

Chemical application – there are several methods for delivering chemicals to the required surfaces, such as foaming, high or low-pressure spraying and immersion. Hence, the chemical selected must be appropriate for the application method. In addition, the chemical concentration must be accurate as per the manufacturer’s recommendation. There are many commercially available dosing pumps to accurately dispense chemicals. Most chemical companies also sell dispensing pumps or chemical dosing tools that help with appropriately diluting the working solution of the chemical. It is important to ensure that regardless of the application method being used, the correct concentration is being delivered to the surface. It is also helpful if the chemical levels can be accurately measured at the application point to check the correct dilution is occurring.