Choosing the right disinfectants for effective biosecurity

We all know that a Defra-approved disinfectant must be used for at least one of the disinfection stages and this must have passed both General Orders and Poultry Orders. For clarification, Poultry Orders is a specific test applying the chemical against avian flu. In the event of a notifiable disease outbreak, the disinfectant must be used at the dilution rate under General Orders. It is also worth remembering that Defra tests at 4ºC , which is much cooler than an average shed, therefore some disinfectants may rate low on Defra’s rating, but will perform well if used at the right temperature for the chemical.

Ensuring enough contact time in line with the manufacturer’s guidance is important – air vents should remain closed and fans should be switched off until the disinfectant has had sufficient contact time. Naturally after this, the shed should be force ventilated to ensure it is safe for re-entry. Foaming disinfectants can increase contact time because they tend to have an extended cling time on vertical surfaces. They are also more visible when being applied so it’s easier to identify any areas that have been missed.

The choice of disinfectant needs to be appropriate for the area or application in question. Water lines, for example, require an oxidising disinfectant such as Huwa-San which will combat biofilm.

Some disinfectants work better at warmer temperatures while others work whatever the ambient conditions. Oxidising disinfectants such as hydrogen peroxide, peracetics, or proxygenes will work in all temperature ranges, whereas glutaraldehyde and formaldehyde disinfectants will take longer to take effect in colder temperatures. Heating the shed up will speed up its effectiveness.be less effective Temperature can affect pests too – for example, if treating for litter beetle, spraying as soon as the birds have left the shed, whilst there is still some residual warmth is essential, because the beetles will retreat to the roof space as soon as the shed starts to cool.

Oxidising disinfectants don’t have a beneficial residual effect whereas glutaraldehyde and quaternary ammonium have up to 7-days residual effect. For this reason, the latter are generally more popular, but oxidising disinfectants are particularly effective against fungal infection (e.g. aspergillus) and have a quicker re-entry time (so can be useful for faster turnarounds). To make the most of a disinfectant with a residual effect, it should be used at the last stage – depending on the product used, it will continue to provide a level of protection for some days after application.

Some disinfectants, such as formaldehyde, are carcinogenic and the health risks are well documented, while others are skin irritants. It is an employer’s responsibility to ensure that users understand the chemicals they’re using and to provide the correct PPE – always refer to the Material Safety Data Sheet. Meters can be used to ascertain when it is safe to re-enter a shed after disinfection, especially after fumigation. Needless to say, different chemical agents should never be mixed, unless advised by the manufacturer.

Cleaning properly at the outset and removing all organic matter is even more important than the subsequent disinfection stages. Spraying disinfectant on top of organic matter is ineffective. Disinfecting onto a wet surface will reduce the effectiveness of the disinfectant as you will essentially be diluting the product further, therefore, always disinfect a dry surface.