Correct methodology of disinfection
Correctly performed disinfection consists of 4 steps:
1. stable/barn preparation
2. cleaning
3. disinfection
4. stable drying and rest period
1. Stable preparation
Preparation of the stable after animal dispatch consists in removal of the minor mobile mechanisms, removal of organic material (fodder, droppings, dirt), removal of dust from high points, draining of the area under the grates and soaking.
Reasons of mechanical cleaning of the whole area:
Organic substances, mainly proteins and fats, render active protection to microorganisms, the so called biofilm. It is very important to remove all organic materials from the hutches, incl. all fodder residues from the troughs. Any impurity dilutes disinfectants, thus impairing their effect.
– Removal of mobile mechanisms out of the stable (dip into water with detergent and then disinfect).
– Perfectly mechanically remove all organic material residues (fodder, droppings). Use shovels, scrapers, brushes – depending on the technology. Mechanical cleaning shall be performed as soon as possible after animal dispatch – before the organic material dries. Troughs for fodder – fill the mechanically cleaned troughs with water containing detergent.
– Dust removal from high points –by vacuum cleaners or by flushing these points.
– Draining the areas under the grates. If these areas cannot be drained fully, the minimum distance of 40 cm between manure level and the grate shall be maintained.
– Soaking is the step enabling better and simpler removal of organic material residues after mechanical cleaning. It is performed either manually by a hose (wap spraying under high pressure is unsuitable, because infect is spread around) or, preferably, by the garden sprayers connected to the timer, spraying the area systematically. This system saves working time of the operator, water consumption and reduces filling of the manure pits (5 minutes spraying, 15 – 50 minutes rest). Water consumption should be 1.5 l/m2.
2. Cleaning
Detergent is applied after area soaking. The detergents contain surfactants facilitating quick cleaning and destructing the microorganism biofilm.
Use of the foam lances is advantageous, because detergent remains longer in contact with the washed areas, namely even on vertical surfaces. Good recognizability of treated and untreated areas is another advantage.
Detergent concentration is estimated at practice by foam thickness and by foam adhesion on the wall (0.5-2 %). The detergent should act for 20 – 60 minutes (no more, no less) and should be applied under low pressure.
The detergents used in the stables usually have alkaline pH and therefore, when used, detergent residues have to be removed thoroughly together with the organic material. Wash all used vessels to avoid reaction with other substances and thus preventing reduction of efficacy of the disinfection applied afterwards.
Protective clothing:
• rubber gloves
• goggles
• simple mask when working with the concentrate
• rubber water resistant clothing
Application of the detergent is followed by washing, when all impurities are removed out of the stable. Harmless water shall always be used for washing. The optimum water flow is 20-40 l/min.; the higher, the better. Water flow is more important than pressure. Water pressure is usually ca 160 bar.
Flushing by water is another step when a high water flow (20-40 l/min.) and a low water pressure < 80 bar is applied. The nozzle with a “flat fan-shaped (arcuate) flow” is used; it is necessary to proceed from the top to the bottom and from the end of the stable towards its exit.
3. Disinfection
Disinfection is performed 1 – 5 hours after flushing. The stable may be neither too dry not too wet. Only this way the maximum number of microorganisms can be eliminated. A too dry stable: the biofilm dries, thus protecting bacteria, viruses and fungi. It is rather troublesome to destruct and remove the biofilm fully. In case of a too wet stable concentration of the used disinfectant is diluted.
Disinfection procedure:
1. Disinfection by spraying 1-5 hours after washing/flushing.
Application of the disinfectant at first on the side walls, railings, then ceiling (utilization of the falling disinfectant on the floor), then spraying on the floor, thus increasing efficacy.
The nozzle should create the “flat fan-shaped (arcuate) flow“, spray rate should be adapted to the surface: plastics – a higher rate, porous surface – a lower rate. The optimum flow after disinfection should be 15 l/min and the pressure should be low – 20 bars.
2. Disinfection 24-48 hours before new animals arrival. Fogging is the most suitable and most effective method. This second disinfection is performed by the end of the step 4, i.e. after stable drying and after its rest.
Consumption of working solution in ml per 1m2 , depending on surface material:
Plastics and flat materials 200
Concrete 300 (standard)
Wood 400
Hardboard 500
Precise disinfectant concentration is important. Lower concentration results in inadequate disinfection and in step-by-step resistance of microorganisms (and thus loss of efficacy of the disinfectant). Higher concentration of the disinfectant results in financial losses.
Method of dilution:
The most precise method of preparation of the working solution needs a large vessel (depending on the size of the area to be disinfected) where the disinfectant will be dissolved.
For preparation of 1% solution:
– vessel 200 l – 2 kg (l) of the disinfectant
– vessel 1000 l – 10 kg (l) of the disinfectant.
Use of wap with suction of the disinfectant can be very inaccurate. Ineffective in case of low consumption, very expensive in case of high consumption.
Consumption:
Area of the room (a x b) x coefficient 3 (floors, railings, other technologies, ceiling, side walls are included) + reserve of ca 10%.
For instance the stable with the walls 30m x 15m long: 30m x15m x 3 = 1350 m2 +10 % = ca 1500 m2 areas for disinfection. If 300 ml is consumed per 1 m2, then 450 l of the working solution is needed. If we have for instance the vessel of 150 l, it is necessary to 3 x 150 l. 1% solution is prepared by dissolving 1.5 kg in 150 l vessel. Because we will prepare the working solution 3x, we shall divide the whole area to be disinfected optically into 3 segments for optimum consumption of the working solution.
Recommended dilution of the solutions is performed by adding the disinfectant into water, NOT vice versa!
Determination of concentration of the disinfectant:
See above and also:
Mainly presence of organic substances, pH and physical and chemical impact of the environment is applied.
Under the physical impact we understand for instance quality of material and porosity – which results in absorption and inactivation of disinfectants of hydrophobicity which repels the disinfectants.
Efficacy of disinfection can be reduced materially during the winter period, when the temperatures are below 15° C) and when the glutaraldehyde and quaternary ammonium salt based disinfectants are used. The medicinal products are tested at 20 °C and at the concentration of 1 %. If the outdoor temperature is lower, it is necessary to observe the general DEFRA recommendations to reach the same efficacy of the used disinfectants:
– if the outdoor temperature is below 10° C – 2 % (double the basic 1% concentration)
– if the outdoor temperature is below 5° C – 5 %.
Under the low temperature microbes only stop to proliferate, but this phase usually is reversible. This recommendation is general and concerns all medicinal products from different producers. The glutaraldehyde and quaternary ammonium salt based disinfectants can be used only during warmer periods of the year or at higher concentration, depending on the temperature. The concentration lower than 1% can be used in these products during the summer months only.
Resistance:
• alternation of disinfectants with different active substances with respect to easier creation of microbe resistance if a single active substance is used
• acquired resistance mainly to pseudomonades and staphylococcuses
• the Virkon series of disinfectants is an exemption; resistance does not occur thanks to three-stage oxidation effect.
Flushing after disinfection by the products Virkon S, Virkon Advanced, Ambicide, Sanitas Forte Vet, HPPA, Virofog, Kilcox Extra and Paraform Prills is not necessary.
Mutual mixing of detergents or mixing of detergents with disinfectants is possible only upon approval of the producer. Mixing can result in changed features and efficacy of individual products.
Protective clothing:
• rubber gloves
• goggles
• simple mask when working with the concentrate
• rubber water resistant clothing
Prevention of salmonellosis:
Hand disinfection prevents possible danger of salmonella infection transfer. Use the asppropriate desinfectant whenever entering the stable.
4. Stable drying and rest
The stable may rest only if washed, disinfected and dried duly. The stable must be closed hermetically and any entry must be prevented. Ventilation must be switched off. The stable should rest for 4 days as a minimum. By the end of this step, i.e. 24-48 hours before new animal arrival, the second disinfection by fogging is applied.