HERD HEALTH                                       PIH80


      Selection and Use of Disinfectants in Disease Prevention

H. Neil Becker, Melrose, Florida
George W. Meyerholz, USDA, Washington, D.C.
Jack M. Gaskin, University of Florida

Glenn and Miranda Elliott, Galivants Ferry, South Carolina
Miksch, University of Kentucky
John Thomson, South Dakota State University
Kurt Wohlgemuth, North Dakota State University

     Cleaning and disinfecting are very important in  controlling
the accumulation and spread of disease-causing microorganisms. It
also improves air quality and reduces dust.  This  is  especially
true in modern swine buildings where continuous use and high con-
centrations of animals may result in a condition referred  to  as
``disease  buildup.''  The  all-in, all-out management program is
recommended to facilitate the cleaning process and to improve pig

     As disease-producing bacteria, viruses, fungi, and  parasite
eggs  accumulate  in  the  environment,  disease  problems can be
transmitted to each successive group of animals raised.  Thorough
cleaning  and  disinfecting  often  provides  the only successful
solution to breaking the disease cycle and controlling the  prob-

     Disinfection can be improved when  the  area  is  thoroughly
cleaned.  Organic  matter  such  as  dirt  and manure can protect
microorganisms and inactivate certain disinfectants. Manure remo-
val  followed  by  a simple scrubbing , a high velocity stream of
water, or a steam generator can do  an  excellent  cleaning  job.
Detergent  solutions hasten dirt and manure removal by increasing
the  wetting  speed  and  breaking  organic  matter  into   small
particles  that  easily  wash away. A siphoning system or propor-
tioner can be utilized to combine a  detergent  or  a  detergent-
disinfectant with the cleaning process. A high pressure stream of
water or spray (200-1000 psi) can be used to  remove  manure  and
debris.  Portable  steam  generators, ``steam jennies,'' are also
used for cleaning dirty surfaces. The nozzle should be  held  not
more  than 6-8 in. from the surface to have much value in killing
organisms. The steam cleaning-detergent process works effectively
on  wood,  metal,  concrete  and  especially  on slotted and wire
floors. Many disinfectants and detergents  work  better  at  warm
temperatures  of the steam generator.  Effective cleaning removes
more than 95% of the contamination and permits  disinfectants  to
more easily penetrate and kill organisms.

Choosing a Disinfectant

     Many factors must be weighed before choosing a proper disin-
fectant for a particular job. A germicide intended for the disin-
fection of a building should work well in the presence of organic
matter,  be  compatible  with soaps or detergents, be harmless to
building materials, and be relatively non-toxic.  A  disinfectant
suitable  for  decontaminating  a building might be too toxic for
use in sanitizing feed and water utensils. Select  the  disinfec-
tant to fit the job.

     Chemical agents have  different  mechanisms  of  action  and
spectra of activity. Warmer temperatures with some disinfectants,
such as those containing chlorine or iodine, drive off the active
ingredient  from  the solution. Some disinfectants are influenced
by an acid or alkaline pH and/or hardness of the  water.  Charac-
teristics and uses of common disinfectants can be evaluated using
Table 1.
Commonly Available Disinfectants

     Saponated solution of cresol is almost insoluble, especially
in  hard water. Compounds of cresol with soap (saponated) such as
LysolO are normally used to increase solubility and  are  applied
in  a  2-4%  solution; a dilution of 4 oz.  of cresol per gal. of
water is recommended. Hot solutions are more effective. Saponated
solution  of  cresol  is  an effective disinfectant to use in the
presence of organic  matter  and  is  suitable  for  disinfecting
animal  quarters, vehicles and premises. These compounds can also
penetrate wooden materials. Cresol has a  strong  and  persistent
odor  to consider when using in farrowing houses or other tightly
enclosed buildings.

     Synthetic phenols such as orthophenol  are  available.  They
have  a  wide  range of antimicrobial activity and are relatively
good in the presence of organic material. They  usually  have  no
objectionable  odor. Some are fortified with synthetic detergents
for one-step cleaning and  disinfecting.   They  are  sold  under
various trade names (see Table 1).

     Free Iodines:  Tincture of iodine (2% iodine in alcohol) and
strong  tincture of iodine (7%) have been used as antiseptics and
disinfectants; but because of their staining, corrosive and  skin
irritant  properties, organic or ``tamed'' iodophor compounds are
commonly used. Tincture of iodine could be used on skin prior to,
or  after,  minor surgical procedures such as castration. As with
alcohols, the proper concentration must be maintained.

     Iodophors are combinations of iodine  and  agents  that  aid
solubility,  usually non-ionic detergents. They are non-staining,
non-irritating, and largely free from the risk of producing  skin
hypersensitivity  reactions.  Iodophors, sometimes referred to as
``tamed iodines'' or ``organic iodines'' are  now  commonly  used
for  disinfection of utensils, equipment and precleaned surfaces.
They are not highly active in the presence of  organic  material.
In  combination with detergents, they provide a slow release ger-
micidal action that has residual activity for  at  least  7  days
after  application.  They  are effective in hard water but should
not be used with alkali soaps.

     Alcohols:  In general, ethanol (grain), methanol (wood)  and
isopropyl  (rubbing) alcohols are not suitable for most disinfec-
tion applications found in  pork  production.  Isopropyl  alcohol
could  be  used  to  maintain  sterility of clean instruments but
other products are usually  better  suited.  After  a  ``surgical
scrub,''  it  could  also  be used as a final application to skin
prior to surgical procedures. If used, proper concentrations must
be maintained (70-78%).

     Chlorine  compounds  have  rapid  action  against  bacteria,
spores,  fungi,  and  viruses.  Preliminary cleaning is essential
before  disinfection  with  chlorine  compounds   because   their
activity  is  substantially  reduced  by  the presence of organic
matter. Solutions of sodium hypochlorite, similar to  those  used
as  laundry  bleaches,  are  commonly used to disinfect utensils.
Such solutions decompose upon exposure to  light  and  should  be
kept  protected. A 2% solution of calcium hypochlorite (bleaching
powder, chloride of lime) is an economical and  effective  disin-
fectant  for  buildings  and  utensils.  Its  action, however, is
readily dissipated by organic matter and careful cleaning  should
precede its use. Powdered chlorinated lime may be dusted directly
on contaminated livestock quarters as a deodorant as  well  as  a
disinfectant.  It should be stored in airtight containers because
it deteriorates when exposed  to  air.  Chloramines  are  organic
chlorine compounds which release chlorine slowly and exert a pro-
longed bactericidal effect. They are less  toxic  and  irritating
than the hypochlorites.

     Lye (soda lye) contains approximately 94% sodium  hydroxide,
a  very  effective  disinfectant.   Concentrated lye is a caustic
poison and must be handled with great care. Solutions of lye will
damage  painted  or varnished surfaces and textiles if allowed to
remain in contact with them for very long. Lye  does  not  injure
bare  wood,  enamelware,  earthenware or any of the common metals
except aluminum. It is not highly effective against  tuberculosis
organisms  and  spore-forming  bacteria  as  commonly  used.  For
highly effective disinfectant purposes, lye should be applied  as
a 5% solution (one 131/2 oz. can to 2 gal. of water).  It is com-
monly used at a lower concentration (1-2 lb. to 10 gal. of water)
that is less hazardous to the user.

     Chlorhexidine is a synthetic compound with action against  a
variety of bacteria and many viruses. It is not appreciably inac-
tivated by small quantities of organic matter and  is  non-toxic.
Chlorhexidine is relatively ineffective against the gram-positive
cocci, Pseudomonas, and resistant  viruses  such  as  the  parvo-

     Quaternary ammonium compounds are surfactants commonly  used
for  general  disinfection  of  dairy,  meat-packing,  and  food-
handling equipment. They are antibacterial  but  do  not  possess
substantial  viricidal,  fungicidal  or sporicidal action and are
used chiefly as  sanitizing  rinses  after  mechanical  cleaning.
These  compounds  are  not  suitable for disinfection of premises
since they are readily inactivated by organic  matter.  They  are
neutralized  by  soaps  so  surfaces  to be disinfected with them
should be pre-rinsed.

     Formaldehyde and other aldehydes  can  be  purchased  as  an
aqueous  solution containing about 40% formaldehyde gas, commonly
known by the name ``formalin.'' A  concentration  of  4%  formal-
dehyde  gas  is a reliable disinfectant that is lethal to anthrax
spores within 15 min. Fumigation with formaldehyde has been popu-
lar  for  use  in  large  poultry  houses and swine units. Proper
disinfection depends on a long period of exposure at proper  con-
centration and humidity. Because the gas tends to condense at low
temperatures, fumigation with formaldehyde  is  unreliable  below
65o F. Temperatures above 80o F are preferred.  Buildings should be
thoroughly cleaned before fumigation and must be aired for  12-24
hr.  before  reuse. There are two methods of fumigating with for-
maldehyde gas. The  first  employs  wide  bottom  buckets  placed
approximately every 10 ft. through the length of the building. In
each receptacle place 175 gm. (10 level tablespoons) of potassium
permanganate,  then  12 oz. (11/2 cups) of a 40% solution of for-
maldehyde (formalin) are poured over it. Under proper  conditions
this  mixture  will generate enough formaldehyde gas to disinfect
1,000 cu. ft. of space. Paraformaldehyde is a white  powder  used
in  commercially  available  electric heating units which release
the gas from the powder. With either method, the floor should  be
moistened about 15 min.  before fumigation; and the building must
be kept tightly closed for at least 8  hr.  Glutaraldehyde  is  a
more  effective  germicide than formaldehyde and has a less irri-
tating odor. However, it is significantly more expensive. A  com-
mercial  spray  fumigant  is  also available.  The formula slowly
releases formaldehyde and kills bacteria on contact and for up to
7  days. Use of fumigants is hazardous to humans and animals; use

Footbath Preparation and Maintenance

     Footbaths  can  be  effective  in  preventing  contamination
through  traffic between buildings (by footwear). They also serve
as a constant reminder of the  need  for  hygienic  measures.  If
footbaths  are not properly prepared and maintained, they are not
only ineffective but act  as  sources  of  further  contamination
while  providing  a sense of false security. The following should
be considered in preparing and maintaining footbaths:

o    The footbath should be long and wide enough  so  people  are
     forced to walk through it.

o    The design should facilitate easy drainage and cleaning.

o    The depth should be at least 4 in.

o    It should be protected from weather (flooding, freezing).

o    Disinfectant  should  be  replaced  when  dirty  (daily,  if

o    Phenols and cresols are most commonly used but iodophors are
     also sold for footbaths.

o    Clean footwear is more effectively disinfected  than  dirty,
     mud, or manure covered footwear. Provide adequate facilities
     (water spray) to easily and thoroughly pre-clean footwear.

Safety Precautions

     Many cleaners and most disinfectants are poisonous. Store in
tightly  closed containers in a safe, locked area out of reach of
children and other unauthorized persons, and away from  feed  and
other  supplies. Do not use bleach and ammonia together. Keep the
labels on all containers. Read and follow  directions  carefully.
Observe  all safety precautions. Avoid skin contact, wear goggles
and avoid breathing of spray mist or fumigant.

Practical Testing for  the  Effectiveness  of  Disinfection  Pro-

     Laboratory testing for the effectiveness of disinfectants or
disinfection  procedures may be complicated and can be misleading
if cleaning and disinfection is  not  done  thoroughly.  However,
veterinarians can provide a practical and simple method (inexpen-
sive) for interested pork producers. Swab  samples  are  obtained
from  surfaces  before  and  after  disinfection and cultured for
various bacterial organisms. A marked difference in the type  and
quantity of bacteria grown in cultures should be seen between the


     Disinfection in Veterinary and Farm Animal  Practice.  1987.
Ed. by Linton, A.H., Hugo, W.B. and Russell, A.D., YearBook Medi-
cal Pub., 35 E. Wacker Dr., Chicago, IL 60601

     Veterinary Pharmacology and Therapeutics. 1988. 6th ed.  Ed.
by  Booth,  N.H.   and  McDonald, L.E. Chapter on Antiseptics and
Disinfectants by Huber, W.G., Iowa State Press, Ames, IA.
|Reference to products in this publication is not intended  to  be |
|an  endorsement  to the exclusion of others which may be similar. |
|Persons using such products assume responsibility for  their  use |

REV 6/90 (5M)

Table 1. Common disinfectants-characteristics and uses.
|                                              Formaldehyde      Chlorine     |
|                                              and other         hypochlorites|
|                              Chlorhexidine   aldehydes         chloramines  |
|Spectrum of activity                                                         |
|  Gram pos. bacteria          S.A.,1 not      Yes               Yes          |
|                              pyogenic cocci                                 |
|  Gram neg. bacteria          S.A., not       Yes               Yes          |
|                              pseudomonads                                   |
|  Tuberculosis bacilli        S.A.            Yes               S.A.         |
|  Bacterial spores            S.A. at 1%      Yes               S.A.         |
|                              concentration                                  |
|  Fungi                       S.A.            Yes               Yes          |
|  Viruses                     S.A., not       Yes               S.A.         |
|                              parvovirus                                     |
|Special properties                                                           |
|  Resistance to organic debrisGood            Good              Very poor    |
|  Effect of hard water        None            None              None2        |
|  Detrimental effect of heat  No              4                 5            |
|  Residual activity           Yes             6                 7            |
|  Most effective pH range     Alkaline        Not affected by pHAcid         |
|  Compatibility with anionic  Yes             Yes               Yes          |
| surfactants (soaps)                                                         |
|  Compatibility with non-     Yes             Yes               Yes          |
| ionic surfactants                                                           |
|Disadvantages                 Reduced activityIrritating fumes,8Inactivation |
|                              against certain                   by organic   |
|                              organisms                         debris       |
|                                                                             |
|Commonly used concentrations                                                 |
|  Disinfecting solution       1%              2-8%              Hypochlorites|
|                                                                3-5% 10,11   |
|  Sanitizing solutions        0.5%            1-2%              Hypochlorites|
|                                                                2-3%11       |
|Appropriate uses                                                             |
|  E - Equipment                                                              |
|  Ce - Clean equipment        E,P,F           E,P,F             CE           |
|  P - Premises                                                               |
|  F - Footbaths                                                              |
|Common brands and             NolvasanO       CidexO            Chloramine-TO|
|  names12                                     DC & RO           ChloroxO     |
|                                              FormaldegenO      HalazoneO    |
|                                              Formalin                       |
|                                                                             |
|                                                                             |
|                                                                             |
|                                                                             |
|                                                                             |

Table 1. (Continue..)
|                                                     Quaternary             |
|                                           Sodium    ammonium    Cresols    |
|                               Iodophors   hydroxide compounds   phenols    |
|Spectrum of activity                                                        |
|  Gram pos. bacteria           Yes         Yes       Yes         Yes        |
|                                                                            |
|  Gram neg. bacteria           Yes         Yes       S.A.        Yes        |
|                                                                            |
|  Tuberculosis bacilli         S.A.        S.A.      No          S.A.       |
|  Bacterial spores             S.A.        Yes (5-10%No          No         |
|                                           solution)                        |
|  Fungi                        Yes         Yes       S.A.        S.A.       |
|  Viruses                      S.A.        Yes       S.A.        S.A.       |
|                                                                            |
|Special properties                                                          |
|  Resistance to organic debri  Poor to fairGood      Fair        Excellent  |
|  Effect of hard water         None2       None      3                      |
|  Detrimental effect of heat   5           No        No          No         |
|  Residual activity            Yes         Yes       No          Yes        |
|  Most effective pH range      Acid        Alkaline  Alkaline    Acid       |
|  Compatibility with anionic   Yes         Yes       No          Yes        |
| surfactants (soaps)                                                        |
|  Compatibility with non-      Yes         Yes       Yes         No         |
| ionic surfactants                                                          |
|Disadvantages                  InactivationCaustic   Incompatible9          |
|                               by organic            w/soaps                |
|                               debris                - limited              |
|                                                     spectrum               |
|Commonly used concentrations                                                |
|  Disinfecting solution        50-75 ppm   2-10%     400-800 ppm Variable   |
|                                                                            |
|  Sanitizing solutions         12-25 ppm             200 ppm                |
|                                                                            |
|Appropriate uses                                                            |
|  E - Equipment                                                             |
|  Ce - Clean equipment         CE          P         CE          E,P,F      |
|  P - Premises                                                              |
|  F - Footbaths                                                             |
|Common brands and              BetadineO    Lye      GermexO     Cresl-400O |
|  names12                      IofecO                Hi-LetholO  EnvironO   |
|                               IsodyneO              San-O-FecO  Tek-TrolO  |
|                               LosanO                WardenO     LysolO     |
|                               Tamed                 ZephiranO   Orthophen- |
|                                 IodineO                         ylphenol   |
|                               WeladolO                          Sodium     |
|                                                                 orthophenyl|
|                                                                 phenate    |
1.  S.A. - Some Activity.
2.  Unless hard water is alkaline.
3.  Reduces speed of kill.
4.  Formaldehyde gas works best at 80-140\(deF.
5.  Use at less than 110\(deF, active principal driven off by heat.
6.  No, except slow-release formulas.
7.  Hypochlorites: No, chloramines: Yes.
8.  Glutaraldehyde is less irritating and is superior to  
    formaldehyde as a germicide.
9.  Strong odor with coal and wood tar distillates.
10. 3.3% Chlorox inactivates parvovirus on clean surfaces.
    Chloramines variable.
12. Products listed are intended as examples, not  
    endorsement; many suitable products are not listed.

Table 2. Definitions.
|Anti-             a prefix meaning against; to prevent.            |
|Antiseptic        an antimicrobial agent sufficiently free of toxic|
|                  effects that may be used on body surfaces, e.g.  |
|                  alcohol, iodine.                                 |
|Antisepsis        the prevention of infection(s) or the result of  |
|                  infection(s).                                    |
|Caustic           corrosive or destructive to living tissues       |
|-cidal            suffix meaning "to kill".                        |
|Detergent         an agent that aids in cleansing; may be used in a|
|                  solution with disinfectants.                     |
|Disease           the result of any condition that allows or       |
|buildup           permits the number of disease producing organisms|
|                  to increase.                                     |
|Disinfectant      an antimicrobial agent that is too toxic,        |
|                  irritating or corrosive to be used on body       |
|                  surfaces but is suitable for use on equipment,   |
|                  floors or environmental areas.                   |
|Fumigation        exposure of an area or object to disinfecting    |
|                  fumes.                                           |
|Germicide         an agent (substance) that kills germs.           |
|Germicidal        the relative ability of an agent (substance) to  |
|activity          kill germs.                                      |
|Germ(s)           disease producing microorganisms.                |
|Hardness          amount of calcium, magnesium, or other minerals  |
|of water          dissolved in water that may interfere with       |
|                  cleansing ability.                               |
|Hypersensitivity  an exaggerated reaction of the body or tissues to|
|reaction          contact with a substance or foreign agent;       |
|                  allergic reaction.                               |
|Micro-            a prefix meaning small; not seen with the naked, |
|                  unaided eye.                                     |
|Microorganism     small, living organisms usually seen only with   |
|                  the use of a microscope.                         |
|Organic Matter    material that comes from living organisms or     |
|                  tissue, e.g., blood, manure, dirt, urine,        |
|                  afterbirth, mucus.                               |
|pH                the symbol used to express whether a solution is |
|                  acidic or basic (alkaline). pH 7 is neutral,     |
|                  below 7 is acid, and above 7 is alkaline.        |
|Proportioner      a device that meters (adds) one substance        |
|                  (solution) to another; as a liquid proportioner. |
|Sepsis            the presence of disease producing organisms      |
|                  (germs) or their toxins in blood or other        |
|                  tissues; putrefaction; decay.                    |
|-static           suffix meaning "to stop".                        |


Cooperative Extension Work in  Agriculture  and  Home  Economics,
State  of Indiana, Purdue University and U.S. Department of Agri-
culture Cooperating. H.A. Wadsworth,  Director,  West  Lafayette,
IN. Issued in furtherance of the Acts of May 8 and June 30, 1914.
It is the policy of the Cooperative Extension Service  of  Purdue
University  that  all  persons  shall  have equal opportunity and
             access to our programs and facilities.