Disinfectants

Disinfection
Disinfection is the act of destroying infectious agents. Disinfectants and disinfection procedures have been widely used for many years in the poultry industry. Natural disinfection agents, such as sunlight, heat, or just simply resting poultry houses, are considered to be of limited use. To sanitize is to reduce the number of bacteria present and also to prevent them from multiplying.
How surface disinfectants work
Most of them kill (bactericidal) but some chemically disrupt the life cycle of the bacterium (bacteriostatic). To inactivate virus, the agent must disrupt the non-nucleic acid protein coat around the nucleic acid gene material content. The content of the virus should be destroyed to make it inactive. Fungal organism is difficult to be destroyed and most fungicides only poison the fungus rather than destroy the fungal cells.
Types
Common Chemicals used for disinfection
Cresol and Cresylic acid
Cresols and cresylic acid are liquid yellow or brown, coal tar derivatives. They are effective against gram positive, gram negative bacteria, most fungi and some viruses and work best in an acid medium. These are some of the other coal tar products that can be used as disinfectant, commonly called as ‘phenyl’.
Phenol
These are also coal tar derivatives with a base of carbolic acid (C6 H5, OH). Synthetic related compounds also fall in this category; phenols have characteristic odour, turn milky in the presence of water and are effective germicides. Such disinfectants are effective against fungi, gram positive and gram negative bacteria but not effective against bacterial spores. Phenol in its pure form is colourless crystals, having a characteristic smell. It is usually used in water solutions with a dilution of 1:1000
Iodine
Iodine compounds are available as iodophors, which are combinations of elemental iodine and an organic soluble agent, usually a nonionic surface action agent that is soluble in water. The compound reacts only with nucleic acid of cell contents. They are disinfectants in an acid situation (pH- 2 to 4), but actively diminish in an alkaline pH and in the presence of organic material. They are effective against gram-positive and gram-negative bacteria, attacking the nucleic acid of the organism. Iodophors are also effective against fungi and some viruses. Iodine has long been recognized as an effective disinfectant. To overcome many of the disadvantages of the earlier products, ‘iodophors’ have been prepared. The term ‘iodophor’ refers to a combination of iodine with a solubilizing agent that slowly liberates free iodine when diluted with water. The solution will be amber (brownish-yellow) in colour. When the solution is colourless, it is no longer effective.
Chlorine
Chlorine is an effective constituent of certain disinfectants described below:
1. Powder forms: a. Calcium hypochorite combined with hydrated trisodium phosphate (less active for short duration). b. Sodium hypochlorite combined with hydrated trisodium phosphate (very active with short disinfecting life).
2. Liquid forms: a. Sodium Hypochlorites b. Organic chloramines c. Chlorine dioxide
Chlorine compounds are good disinfectants when free chlorine is available in abundance (200-300ppm). When elemental chlorine or hypochlorites are added to water they produce hypochlorus acid (HOCL) which produces the bactericidal action.
Quaternary ammonium
These compounds are cationic (have positively charged ions), odourless, clear, generally non-irritating, have deodourizing and detergent action and are quite effective as surface disinfectants. The most common is alkyl dimethyl benzyl ammonium chloride.
A solution of 500 ppm quaternary ammonia, 200 ppm EDTA (ethylene diamine tetra-acetic acid) and sodium carbonate to adjust pH to about 8.0 (about 200 ppm) is an excellent hatchery disinfectant. It may be used on floors, walls and incubator trays. This should not be used in meat and egg processing plants. Precaution should be taken where foods are involved.
Formaldehyde
Formaldehyde is a gas. It is sold commercially in a 40% solution with water as formalin. Formalin is a very effective disinfectant, also cheap and easily available. It is used for fumigation of poultry house, brooder, and hatchery with potassium permanganate. Formaldehyde is usually generated by adding formalin to potassium permanganate in an earthen pot, or metal container.
Fumigation or fogging
After setting up the house formaldehyde fumigation is done after closing all the sides so that the fumes are retained in the shed for a longer time. Now days the traditional method of formaldehyde fumigation has been replaced by safer chemicals either applied with fogging machines, or as a fine spray after making the house air tight. It is extremely irritating to the conjunctiva and mucous membranes, and some people are very sensitive to it.
Formaldehyde (HCHO) and formaldehyde fumigation:  It is a powerful disinfecting agent in 10% formalin water solution and is the most commonly used as hatchery disinfectant.
Formaldehyde fumigation of incubators and fumigation chamber: Formaldehyde is commercially available as a 40% solution in water (37% by weight) known as formalin, and a powder, Para formaldehyde contains 91% formaldehyde. When either product is heated, formaldehyde gas is produced. It is a highly irritant and toxic, with a tolerance of 5 ppm in the air; inhalation should be avoided. The skin is very sensitive to formalin and there should be no direct contact. Long exposure to this gas will cause irritation to the eyes.
Methods of generating formaldehyde gas
The methods commonly used are:
1. Potassium permanganate method
2. Para formaldehyde method
3. Evaporation of formalin solution
Potassium permanganate method: Two parts (by volume) of formalin are mixed with approximately one part (by weight) of potassium permanganate. When the entire gas is expelled the left out powder will be brown in colour. If sufficient amount of Potassium permanganate is not used then the powder will be wet in consistency. If too much of Potassium Permanganate is added then the residue will be purple in colour. Varying concentration of formaldehyde gas is necessary to fumigate under different conditions as mentioned below:
2. Normal or Single strength concentration: This is obtained by mixing 40 ml of formalin with 20g of potassium permanganate for each 2.83m3 (100 ft3) of closed space. This is also called 1 - X concentration.
3. Double strength concentration: By mixing 80 ml of formalin with 40g of permanganate for each 2.83m3 (100ft3) of space. This is called 2 - X concentration.
4. Other concentration: Other concentrations are 3 - X and 5 - X. The amount of formalin and permanganate to be used will depend on the size of the incubator or the chamber and the desired strength of the fumigation.
The capacity of the incubator is obtained by multiplying together the internal width, height and depth of compartment to be fumigated, making no allowance for the space occupied by the eggs, the trays and all the internal fittings. The container should be made of metal and at least 50 times the volume of formalin to be used so as to prevent chemical overflowing during the reaction.
Para formaldehyde method: Para formaldehyde is a white powder or pellet and is more easily handled than potassium permanganate and formalin. The powder should be placed in an electric skillet or electric pan with the thermostatic control set at 450oF (232oC); for obtaining the normal or single strength (1 - X) concentration, use 10 g of Para formaldehyde for each 2.83 m3 (100 ft3) of space. The gas will be released after 20 minutes of heating. It is advisable to add a little water to the pellet before heating, to raise the relative humidity between 60 and 80 per cent.
Evaporation of formalin solution: A 40 per cent solution of formalin is often used in regulated quantities for the fumigation of hatchers during the egg pipping and hatching period. Some hatchers are fitted with a special tray or cup for this purpose or the formalin may be placed in an enamel coated or earthen container on the incubator floor. The formalin is used at the rate of 60ml per m3 of hatcher space placed in an enamel pan 24 hours after transfer of chicks. Formaldehyde gas evaporates from the formalin solution throughout the period the eggs are in the hatcher, thus reducing the micro-organism population of the hatchery environment.
Temperature and humidity for maximum formaldehyde disinfection: The efficiency of the formaldehyde gas is increased in the presence of heat and moisture. It is impossible to get maximum results unless the temperature of the area to be fumigated is 24oC (75oF) or higher and the relative humidity is 75% or more.
Neutralising formaldehyde gas with ammonium hydroxide: In certain cases it is necessary to stop the action of formaldehyde gas after the required period of fumigation is over. Usually this is accomplished by opening the air inlets and exhausts in the incubators or rooms but often this method is too slow. Ammonium Hydroxide (NH4OH) may be used to expedite the process. A solution of 16 to 20 per cent ammonia should be used. Check to see how much formalin was used, then sprinkle the same amount of ammonium hydroxide on the floor of the area fumigated. In case of Para formaldehyde, use 2 ml of ammonium hydroxide for each gram of Para formaldehyde used.
Strength of formaldehyde fumigation
Varying concentrations of formaldehyde gas are needed under different conditions and the length of the fumigation period is variable. The gas is detrimental to living embryo and to the newly hatched chicks and hence care must be exercised that the concentration of the gas and length of the fumigation period meet the requirements to kill all the pathogenic organisms possible but not lethal to the embryo or chicks. See Table below for detailed recommendations in this regard.
Fumigation level per 2.83m3 (100ft3)
To produce formaldehyde gas
(mix together) To produce equivalent amount of formaldehyde gas
Strength Formalin (ml) Potassium permanganate(g)Para formaldehyde powder (g)
Single (1 - X) 40 20 10
Double (2 - X) 80 40 20
Triple (3 - X) 120 60 30
(5 - X) 200 100 50
Special direction for fumigation
1. Fumigating eggs soon after laying:
Fumigating with 3 - X concentration of formaldehyde for 20 minutes will kill about 97.5 to 99.5% of the organism on the shells of brown eggs and about 95.0 to 98.5% of those on white eggs, the difference probably being due to the fact that brown eggs have a thicker cuticle which absorbs more gas.
Formaldehyde fumigation concentration recommendations
Concentration of fumigant Fumigation duration(min.)Neutralizer amm. Hydroxide
Hatching eggs immediately after lay 3 - X 20 No
Eggs in incubator (1st day only) 2 - X 20 No
Chicks in hatcher 1 - X 3 Yes
Incubator room 1 - X, 2 - X 30 No
Hatcher between hatches, Hatchery room, chick room, Wash Room and Chick boxes 3 - X 30 No
Trucks 5 - X 20 Yes
2. Fumigating chicks:
Chicks that have been hatched should not be exposed to concentrated fumigation by rapid gas release. Formaldehyde fumigation colours the down of the chicks to deep orange and is often noticeable. Chick’s fumigation therefore should be considered on emergency measure only. (Only in case of Omphalitis outbreaks)
3. Fumigating between hatches:
After the chicks have been removed from the hatchers, and the trays washed, sun dried. The hatchers, trays, hatcher cabin and wash room should be fumigated with formaldehyde gas.
4. Fumigating chick trucks:
After thoroughly cleaning the truck, it may be fumigated in a specially constructed tent covering its whole body and chassis with 5 - X concentration.
5. Egg must never be fumigated between the 24th and 96th hour after setting in the incubator, as it is the critical period of incubation of breed able eggs.
Copper Sulphate
Copper sulphate is toxic to fungi. A 0.5% solution is generally used for destroying fungi on feed, hoppers, utensils, water fountains, and surrounding areas associated with outbreaks of fungal disease.
Chlorinated Lime (Bleaching powder)
Chlorinated lime or bleaching powder, prepared by saturating slaked lime (i.e. lime treated with water) with chlorine gas, is one of the earliest recognized disinfectants. It has corrosive effect on metals and skin, and therefore should be used cautiously after proper cleaning of floor. A 20 percent solution is used for disinfecting floor and utensils for feed and water. However, chlorinated lime has now been largely replaced by hypochlorite. If used according to directions, hypochlorite is highly efficient. Their main use is for egg washing and sanitizing, and for disinfecting incubators, and hatcher trays, small brooders, and water and feed containers. They can also be used on cement surfaces. All surfaces to be disinfected with hypochlorite solutions must first be thoroughly cleaned to ensure the greatest efficiency.
Lime
Lime is commonly used as a disinfectant for litter, floor, and poultry carcasses. It is mainly used in areas that are damp and cannot be exposed to the sun, as well as for disinfection of drains and sewerages. The action of lime depends on liberation of heat and oxygen when the chemical comes in contact with water. Heat destroys bacteria and parasitic eggs and even coccidia, and keeps fungi under control. It should be applied liberally using at least 4-7 kg/100 square feet. For disinfection of poultry manure, lime should be added at the rate of 90 kg / ton of manure. It also disinfects wall and crevices, if a solution containing 38 parts lime and 15 parts sodium chloride is used for washing the wall. As lime has a caustic action, birds should be kept away from it, until it has become thoroughly dry.