Selection and Use of Disinfectants in Disease Prevention
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FACT SHEET 19.46.07 HERD HEALTH Extension Bulletin E-1596, January 1982 COOPERATIVE EXTENSION SERVICE • MICHIGAN STATE UNIVERSITY Selection and Use of Disinfectants in Disease Prevention Authors Reviewers George W. Meyerholz, USDA, Extension Service, David M. Bedell, University of Georgia Washington, D.C. Glenn Elliott, Galivants Ferry, South Carolina Jack M. Gaskin, University of Florida Dennard R. Hill, Seaford, Delaware Wayne Rawson, Milledgeville, Illinois Cleaning and disinfecting is very important in con- 95 percent of the contamination and permits disinfectants trolling the accumulation and spread of disease-causing to more easily penetrate and kill infective organisms. microorganisms. This is especially true in modern swine buildings where continuous use and high concentrations of Choosing a Disinfectant animals may result in a condition referred to as "disease Many factors must be weighed before choosing a buildup." As disease-producing bacteria, viruses, fungi, proper disinfectant for a particular job. For example, a and parasite eggs accumulate in the environment, disease germicide intended for the disinfection of a building should problems can be transmitted to each successive group of work well in the presence of organic matter, be compatible animals raised. Thorough cleaning and disinfecting often with soaps or detergents, be harmless to building materials, provides the only successful solution to breaking the dis- and be relatively non-toxic. A disinfectant suitable for de- ease cycle and controlling the problem. contaminating a building might be too toxic for use in sani- Because organic matter, such as is found in dirt and tizing feed and water utensils. Select the disinfectant to fit manure, inactivates certain disinfectants and protects in- the job. fective microorganisms from germicidal activity, good Several other factors influence the performance of dis- cleaning practices are necessary for proper disinfection. infectants. The various chemical agents have different Manure removal followed by a simple scrubbing, a high mechanisms of action and spectra of activity. Most dis- velocity stream of water, or a steam generator can do an infectants work better at warmer temperatures but with excellent cleaning job. In addition, the use of detergent some disinfectants, such as those containing chlorine or solutions hastens dirt and manure removal by increasing iodine, excessive temperatures may drive off the active the wetting speed and breaking organic matter into small ingredient from the solution. Disinfectants are also in- particles that easily wash away. A siphoning system orpfb- fluenced by an acid or alkaline pH. Hardness of the water portioner can be utilized to combine a detergent or a de- may affect some disinfectants. For the purpose of evalua- tergent-disinfectant with the cleaning process. A high ting characteristics and uses of common disinfectants, pressure stream of water or spray (200-1000 psi) removes Table 1 may be used. manure and debris with great efficiency. Portable steam Several disinfectants are commonly available to pork generators, "steam jennies," are also excellent for clean- producers: ing dirty surfaces but the nozzle would have to be held not Saponated solution of cresol is a popular disinfect- more than 6-8 in. from the surface to have much value in ant. Cresol is almost insoluble, especially in hard water. killing organisms. The steam cleaning-detergent process Compounds of cresol with soap (saponated) such as works effectively on wood, metal, concrete and other sur- "Lysol" are normally used to increase solubility and are faces. It is especially helpful in cleaning slotted and wire applied in a 2-4 percent solution; a dilution of 4oz. of cresol floors. An additional advantage of the steam generator is per gal. of water is recommended. Hot solutions are more that many disinfectants and detergents work better at effective. Saponated solution of cresol is one of the best warm temperatures. Effective cleaning removes more than disinfectants to use in the presence of organic matter and is suitable for disinfecting animal quarters, vehicles and appreciably inactivated by small quantities of organic premises. Cresol has a strong and persistent odor that may matter and is quite non-toxic. Chlorhexidine is relatively in- make it objectionable in farrowing houses or other tightly effective against the Grampositive cocci, Pseudomonas, enclosed buildings. and resistant viruses such as the parvoviruses. Synthetic phenols such as orthophenylphenol are Quaternary ammonium compounds are surfactants now available. They have a wide range of antimicrobial commonly used for general disinfection of dairy, meat- activity and are relatively good in the presence of organic packing, and food-handling equipment. They are anti- material. They usually have no objectionable odor. Some bacterial but do not possess substantial viricidal, fungicidal are fortified with synthetic detergents for excellent one- or sporicidal action and are used chiefly as sanitizing step cleaning and disinfecting. They are sold under various rinses for eating, drinking and dairy utensils after mechani- trade names (see Table 1). cal cleaning. These compounds are not suitable for disin- lodophors are combinations of iodine and agents that fection of premises since they are readily inactivated by aid solubility, usually non-ionic detergents. They are non- organic matter. They are also neutralized by soaps so sur- staining, non-irritating, and largely free from the risk of faces to be disinfected with them should be pre-rinsed. producing skin hypersensitivity reactions, lodophors, Formaldehyde and other aldehydes are disinfectants sometimes referred to as "tamed iodines" or "organic that are gaining in popularity. Formaldehyde can be pur- iodines" are now commonly used for disinfection of uten- chased as an aqueous solution containing about 40 per- sils, equipment and precleaned surfaces. They are not cent formaldehyde gas, commonly known by the name highly active in the presence of organic material. In combi- "formalin." A concentration of 4 percent formaldehyde gas nation with detergents, they provide a slow release germ- is an excellent and reliable disinfectant and is lethal to icidal action that has residual activity for at least 7 days anthrax spores within 15 min. Fumigation with formalde- after application. They are effective in hard water but hyde has been popular for use in large poultry houses and should not be used with alkali soaps. swine units. Proper disinfection depends on a long period Chlorine compounds have rapid action against bac- of exposure at proper concentration and humidity. Be- teria, spores, fungi, and viruses. Their activity, however, is cause the gas tends to condense at low temperatures, substantially reduced by the presence of organic matter so fumigation with formaldehyde is unreliable below 65 F.; that preliminary cleaning is essential before disinfection temperatures above 80 F. are preferred. Buildings should with chlorine compounds is undertaken. Solutions of so- be thoroughly" cleaned before fumigation and must be aired dium hypochlorite, similar to those used as laundry bleaches, for 12-24 hrs. before reuse. There are two methods of fumi- are commonly used to disinfect utensils. Such solutions gating with formaldehyde gas. The first employs wide bot- decompose upon exposure to light and should be kept pro- tom buckets placed approximately every 10 ft. through the tected. A 2 percent solution of calcium hypochlorite (bleach- length of the building. In each receptacle place 175 gm. (10 ing powder, chloride of lime) is a cheap but effective dis- level tbsp.) of potassium permanganate, then 12 oz. (114 infectant for buildings and utensils. Its action, however, is cups) of a 40 percent solution of formaldehyde (formalin) readily dissipated by organic matter and careful cleaning are poured over it. Under proper conditions this mixture should precede its use. Powdered chlorinated lime may be will generate enough formaldehyde gas to disinfect 1,000 dusted directly on contaminated livestock quarters as a cu. ft. of space. Paraformaldehyde is a white powder used powerful deodorant as well as a good disinfectant. It should in commercially available electric heating units which re- be stored in airtight containers because it deteriorates lease the gas from the powder. With either method, the when exposed to air. Chloramines are organic chlorine floor should be moistened about 15 min. before fumigation; compounds which release chlorine slowly and exert a pro- and the building must be kept tightly closed for at least longed bactericidal effect. They are less toxic and irritating 8 hrs. Glutaraldehyde is a more effective germicide than than the hypochlorites. formaldehyde and has a less irritating odor. However, be- Lye (soda lye) contains approximately 94 percent cause of its expense, it may not be as suitable as formalde- sodium hydroxide, a very effective disinfectant. For highly hyde for large-scale disinfection of buildings and equip- effective disinfectant purposes, lye should be applied as a ment. A commercial spray fumigant is also available. The 5 percent solution (one 1314 oz. can to 2 gal. of water). It is formula slowly releases formaldehyde and kills bacteria on commonly used at a lower concentration (1 -2 lbs. to 10 gal. contact and for up to 7 days. Use of fumigants is hazardous of water) that is less hazardous to the user. Concentrated to humans and animals; use properly. lye is a caustic