DISINFECTION IN GENERAL

Sterilisation

A treatment that kills all infectious organisms including spore stages is called a sterilisation. This is not attainable and unnecessary under practical conditions for a poultry production.

Chemical disinfection

Chemical disinfection means that bacteria, fungi, spore and viral gets in contact with chemicals which interfere with the chemical processes in the microorganisms, in such an extent, that the microorganism dies or being unable to multiply.

Disinfection is performed after a thorough cleaning. It is absolutely necessary that all visible and invisible dirt and biofilm be removed before disinfection. 

What kind of treatment that is necessary to achieve efficient disinfection, must be considered in every single concrete situation? It depends on what kind of microorganisms are present and how big the “problem” is.

Poultry farm disinfection is done:

•   at outbreak of infectious disease to eliminate all germs and to prevent spreading    of germs

•   as extra precautions by building infection barrier between flocks and production places

•   to achive better production results.

•   preventive to maintain a low amount of germs in production facilities

Different methods of disinfection

Disinfection can be performed in several ways. The most usual is traditional surface-disinfection where it is important that every square millimetre is treated. This is done best by low pressure. Either by making a pre-mixed solution in an IBC, or a 200-litre drum, to supply a low-pressure sprayer or by using an uptake probe or venture probe to supply concentrate directly into a pressure washer set to low pressure. The latter can be very inaccurate and need careful calibration and monitoring. If the dosage is too weak, ineffective disinfection is a risk and if the dosage is too strong, it is a waste of chemical and money and the ventilation time may have to be increased. It is important to be extra thorough behind poles, pipes, and other hidden areas, as for example underneath horizontal surfaces. Remember that a chain is never stronger than its’ weakest link. If several square millimetres are not treated with the disinfectant, the entire job may be wasted. If there is any doubt that complete coverage has been achieved it is a good idea to disinfect again. This time, start from the other end and work your way in the opposite direction. In this way, the same patches should not be missed twice.

The agent used should be as quick acting as possible, and then it is necessary merely to wet the surfaces. If the disinfectant takes 30 minutes to work, obviously the surfaces must be kept moist for 30 minutes, or if it takes 1 hour to work, the surfaces have to be moist for 1 hour. If the surfaces dry within the time-factor of the disinfectant used, re-treatment may be necessary. By use of slow-working agents (3-4 hours) large amounts of solution are necessary since the surfaces must be kept wet during the whole period it takes for the agent to disinfect completely and thoroughly.

A disinfectant that is active at low temperatures should be used since, in this way, disinfection-failure during winter and on cold metal objects etc. is avoided.

If corrosive products are used, these have to be rinsed off after the end of the acting time. Remember to read in the instructions for each product how long a ventilation period is required and which protective clothing and equipment have to be used.

Fogging

This is an alternative to manual surface-disinfection using a hot or cold fogger that always requires personal protection gear such as masks, goggles and protective clothing. These automatic machines fill the building with disinfecting droplets, which penetrate everywhere and disinfect all surfaces if used correctly.

Many precautions have to be taken when fogging. The ventilation system must be closed and sealed relatively tightly; it is often necessary to place plastic hoods on the outlets of ventilation pipes, the temperature must be adjusted and the fogger must be big enough for the volume of the building that is to be disinfected. If the machine is too small, the room will not be saturated with the disinfecting fog and coverage will be inadequate in places.

The disinfectant used must be a formulation that is recommended for this form of disinfection. This means that some agents cannot be used due to inability to survive the high temperatures which hot fogging involves; others due to the liquid being too dense and therefore not forming suitable droplets.

Cold fogging is becoming more and more popular and if performed correctly, it gives good results. Many of the same rules apply to cold as well as hot fogging. However, the machines are somewhat easier to manage and therefore it is sometimes easier to achieve good disinfection with these.

Remember to disinfect manually on the backside of the ventilation lid, if the house has side ventilations in the walls.