Transmissible Diseases Handbk VIII. GUIDELINES FOR CLEANING AND DISINFECTION IN ZOOLOGICAL GARDENS Matti Kiupel, Rbin Mecklem, Birgit Hunsinger and Rachel E. Marschang Diagnstic Center fr Ppulatin and Animal Health (MK) and Office f Radilgical, Chemical and Bilgical Safety (RM), Michigan State University, Michigan, USA Institut für Umwelt- und Tierhygiene (REM, BH), Hhenheim University, Garbenstr. 30, 70599 Stuttgart, Germany Intrductin Hygienic measures are a majr cmpnent fr preventin f infectius diseases in zlgical exhibitins. A clean envirnment is nt nly a key feature in disease cntrl, but als attractive t the public. Preventive health care cnsists f multiple cmpnents f equal imprtance including fd strage, preparatin and handling, insect and vermin cntrl and cleaning and disinfectin (Fwler, 1978). The purpse f this chapter is t prvide guidelines fr cleaning and disinfectin t the range f peple wh wuld be invlved in managing a disease emergency invlving a z, zlgical garden, game park, circus r any ther facility keeping extic animals. Fr the infrmatin in this chapter t be effective, it is imprtant that the described cleaning and disinfectin methds are incrprated int the rutine husbandry and emergency prcedures. The gal is t prvide individual zs with infrmatin that can be used t develp their wn specific cleaning and disinfectin prtcls. Each f the fact sheets in the Transmissible Disease Handbk cntains disease specific infrmatin abut preventin and cntrl f diseases in zs and suggested disinfectants fr animal husing. Therefre, the purpse f this chapter is nt t prvide detailed infrmatin n specific disinfectants fr the diseases listed in this handbk, but rather t prvide an verview f the guiding principles f cleaning and disinfectin in zlgical gardens and t review the varius classes f chemical disinfectants. Defining Disinfectin The term disinfectant is defined as an agent that frees frm infectin, usually a chemical agent but smetimes a physical ne, such as x-rays r ultravilet light, that destrys diseases r ther harmful micrrganisms but may nt kill bacterial spres (Blck, 2000). Disinfectants are used n inanimate surfaces and are assumed t act rapidly and efficiently t kill r inhibit grwth f micrrganisms. In the veterinary care envirnment, disinfectin is mst effective fr diseases that are nt vectr-brne, but are acquired by direct cntact with cntaminated fluids r animal prducts (Quinn, 2000). Therefre it is imprtant t recgnize that disinfectants play a critical, yet limited rle in infectin cntrl. Insect and vermin cntrl are equally imprtant in preventing infectius diseases, especially fr the cntrl f insect-
brne diseases that present particular challenges in zs. Techniques available t minimize insect-brne disease spread include the use f anthelmintics and insecticides thrugh direct applicatin n at-risk species r thrugh the spraying f husing f susceptible animals. The assistance f epidemilgists and entmlgists shuld be sught t establish insect traps within the z fr insect identificatin and t identify ptential areas f a high-risk expsure. Fr situatins where resistant micrrganisms are present, r animals may be susceptible t infectin due t their health status r the invasiveness f the prcedure t be perfrmed, a sterilizatin methd shuld be used fr treatment f cntaminated items r surfaces. Sterilizatin is achieved when all living micrrganisms and bacterial endspres have been destryed. Cmmn methds f sterilizatin include, dry heat, mist heat, and expsure t specific chemical cmpunds. Fr dry heat sterilizatin, surfaces must be expsed t 160 C t 170 C fr perids f 2 t 4 hurs (Heinshn et al., 1995). Sterilizatin by steam may be accmplished by expsing cntaminated surfaces t mist heat at 121 C fr at least 15 minutes (Quinn, 2000) This will nt be sufficient fr certain heat resistant rganisms such as sme thermphilic spres and prins. Chemical sterilizatin may be suitable in situatins where items t be sterilized cannt withstand the temperatures and physical cnditins required fr dry heat r steam sterilizatin. Chemical sterilants may be used in the frm f a vapr r gas, such as frmaldehyde r ethylene xide, r as an immersin liquid such as glutaraldehyde. These chemical cmpunds and the requirements fr their prper use will be discussed in a later sectin f this chapter. The efficacy f a certain disinfectin r sterilizatin prtcl will depend n a number f factrs. The nature f the surface that is t be disinfected plays an imprtant rle. An uneven surface will be mre difficult t disinfect than an even ne. Dirt will interfere with the disinfectin. Anther imprtant factr are the pathgens present. Sme pathgens are mre difficult t inactivate than thers. The mst difficult t inactivate are bacterial spres and prins. Fr disinfectin, nn-envelped viruses can als be a challenge. Rle f Cleaning and Disinfectin in Infectin Cntrl Having an effective cleaning and disinfectin plan is a crucial step in every bisecurity prgram. Such a prgram shuld be instituted fr every new building and facility and shuld be revised after the ccurrence f an infectius disease and prir t the intrductin f new animals. The main purpse f a cleaning and disinfectin prgram is t reduce the number f pathgens (disease-causing agents) in the envirnment and thereby t reduce the ptential fr diseases t ccur. The first step in an effective disease cntrl plan is an exact identificatin f the rutes hw infectius agents may enter zlgical gardens (inputs), and hw they may spread thrughut the z t ther facilities and utside the z t becme a threat t farming peratins r pssibly humans. Inputs int and utputs frm zlgical institutins may vary depending n the type f the facility. Animal inputs may include: animals intrduced frm ther facilities within the same institutin, animals frm institutins, either frm within Eurpe, r imprted frm anther cntinent, animals cnfiscated by custms/quarantine fficers, sick r injured animals brught in by members f the public, free-ranging animals, which may be either native (rats, mice, birds), r feral (including cats and dgs), and animals imprted frm farming
peratins. Feed inputs include dry prcessed preparatin (cncentrates, hay, pellets, seed etc.) and wet feed, including fresh fruit, fish, meat, vegetables and pasture silage. Bilgical specimens cnfiscated by custms and quarantine fficers are smetimes brught t zs fr identificatin. Semen and embrys may be imprted fr breeding purpses. Varius vehicles mve int the facility and may be cntaminated. Other materials entering the facility include materials used during the imprtatin f the animals (hay, sawdust, crates etc.). Persnnel entering the premises fr nrmal wrk purpses may have cntact with ther animals (pets/farm animals) utside f wrk hurs. Lcal and internatinal visitrs pass thrugh the premises n a daily basis and may intrduce disease. Animals may leave the facilities fr a number f reasns including: exchange and sale f animals, relcatin f animals t ther facilities within and utside the institutin, use f animals in public relatins exercises, i.e. animals taken t shws, shpping centers, schls and televisin statins, animals taken hme by staff fr hand rearing, free-ranging f native and feral animals, including cats and dgs that may have had cntact with animals/animal waste. Waste materials that have t be remved frm the premises may include hay and cmpsted feces, effluent, sme f which has secndary treatment, and a small prtin with tertiary treatment, waste-water. Bilgical specimens and feces are sent t labratries fr testing and bilgical specimens are smetimes als sent t museums, veterinary schls etc. In sme institutins, ffal and carcasses are taken ff the prperty fr dispsal r may be sent t veterinary schls fr necrpsy. Vehicles, crates and packing material used in the transprtatin f animals are all regularly mved ff the premises. Pssible utputs related t peple include persnnel wh have been in cntact with animals and waste prducts (cntaminated clthing and ftwear), and visitrs wh may have been in cntact with animals. Due t the public rle f zlgical gardens, it will be impssible t clean and disinfect all inputs and utputs. In particular, visitrs and the media wuld nt except the impsitin f cleaning and disinfectin prgrams nt them. Therefre a strict cleaning and disinfectin prgram f the animal premises incrprated int daily rutines becmes even mre imprtant. In additin, it is useful t identify premises accrding t their expsure t infectius agents t select the prper cleaning and disinfectin regimes and t pssibly limit the access t such premises. Areas (culd be all r part f a facility) in which an infectius disease exists, is believed t exist, r which may harbr the infective disease agent shuld be classified as an infected premise (IP). Dangerus cntact premises (DCP) are premises cntaining animals with n clinical signs that were expsed t an infectius disease and therefre will be subjected t disease cntrl measures. Suspect premises (SP) are areas cntaining animals that shw n clinical signs, but may have been expsed t an infectius disease thrugh pssible cntact with infected animals r facilities, peple, equipment, semen r embrys, r animals with evident disease symptms, but n cnfirmed diagnsis. Using this classificatin in cmbinatin with specific cleaning and disinfectin prgrams and ther measures, such as insect and vermin cntrl, as well as treatment, vaccinatin and quarantine f infected and expsed animals r animals at high-risk fr infectins, will help t cntrl and t eliminate an infectius disease after an utbreak has ccurred. In sme cases, it may als be necessary t cnsider culling certain animals that have been expsed t disease. Dispsal f animal carcasses in the case f a disease utbreak shuld als be incrprated int these plans.
Cleaning befre Disinfectin The first step in any cleaning and disinfectin prgram is cleaning. Cleaning is the remval f rganic material (i.e., feces, urine, bld, bedding, fd, dust etc.). Disease agents are ften prtected by such materials and can survive the disinfectin prcess. Therefre, thrugh cleaning f a building prir t the disinfectin is required. The cleaning prcess can include a dry cleaning and a wet cleaning step. Dry cleaning physically remves the rganic material befre the actual wet cleaning. Wet cleaning, as the name implies, invlves the use f water. There are 4 basic steps in the wet cleaning prcess: saking, washing, rinsing, and drying. The use f detergents will ften benefit the wet cleaning prcess. Hwever, it is mre imprtant t have pressure washers with the prper pressure (500-800 psi) t ensure that all rganic materials are remved frm the facilities. The final step fr ensuring prper cleaning is t dry the wet areas f the building quickly. If the building is nt dried prperly, the excess misture can result in bacteria multiplying t higher levels than prir t cleaning. It is vital t make sure the cleaning prcedure is dne prperly, as an imprper cleaning can actually increase the lad f infectius agents! If dne prperly, a gd cleaning can remve 90% f all pathgens (Ftheringham, 1995). Special care must be taken when cleaning facilities that are cntaminated with suspected zntic r highly cntagius animal pathgens. All persnnel shuld wear prtective clthing, ftwear and if necessary face masks, gggles, and headwear. After the cleaning f facilities, prper care must be taken f the prtective clthing and equipment that has been used fr cleaning and dispsable prducts shuld be dispsed as bihazards. Organic material remved during cleaning may als cntain pathgens and shuld be treated accrdingly. The last step in a cleaning and disinfectin prgram is the actual disinfectin prcess that will further reduce pathgens in the facilities. Disinfectin is especially useful in reducing infectin risks in yung animal nursery facilities, and in rutine cleaning peratins f animal quarters and feeding utensils. T maximize the effectiveness f a cleaning and disinfectin prgram, it is crucial t mdify such a prgram based n the suspected pathgens that shuld be eliminated r reduced. In additin, specific disinfectants may be selected fr certain knwn micrbial cntaminants fllwing an infectius disease utbreak. It is als imprtant t remember that many disinfectants can be txic t the animals, r may be caustic r crrsive. Animals must usually be excluded frm facilities being disinfected. After a suitable envirnmental expsure time t such disinfectants premises shuld be rinsed thrughly, befre animals are allwed t return. Levels f Disinfectin Disinfectants are tested fr their bactericidal, tuberculcidal, spricidal, fungicidal, virucidal (against envelped and nn-envelped viruses), and antiparasitic (against eggs and cccidia) effects. They can generally be categrized int 3 grups based n their ability t inactivate certain micrrganisms. High-level disinfectants are effective against bacterial endspres under specific cnditins. Intermediate-level disinfectants include thse prducts that can inactive tubercle bacilli, but d nt kill bacterial spres. Such prducts are cmmnly marketed by manufacturers as tuberculcidal. Finally, nrmal ( lw-level ) disinfectants include prducts that kill vegetative bacteria and fungi but are nt reliable fr the destructin f bacterial endspres, tubercle bacilli r small nn-envelped viruses within a practical perid f time (Bthe, 2000).
When selecting a disinfectant fr use n items that will cme in cntact with patients during animal care prcedures, the invasiveness f the prcedure and cmpsitin f the medical device must be cnsidered. A system fr classifying such devices was develped by Spaulding in the 1970s. This system has been recgnized and referenced since that time by many human healthcare rganizatins like the Assciatin fr Prfessinal in Infectin Cntrl and Epidemilgy (Rutala, 1996). Althugh this system was develped fr human healthcare, there are ntable similarities t prcedures and devices used in veterinary care envirnments. These principles may be adapted fr disinfectant selectin purpses in zlgical gardens and ther extic animal cntainments. The Spaulding system categrizes devices int 3 grups based n the risk f infectin invlved with their use: critical, semicritical and nncritical. Critical devices are thse that bear a substantial risk f acquiring infectin if cntaminated with micrrganisms at the time f use. Devices that are intrduced directly int the bdy such as needles, scalpels, catheters and implants fall int this categry. These items must be sterilized in between animal use (Faver and Bnd, 2000). When chsing a sterilizatin methd, cnsideratin must be given t the impact f the sterilizatin prcess n the integrity f the device. Semicritical devices are thse items that cme in cntact with mucus membranes but d nt nrmally penetrate the skin. Examples f these devices include endscpes, brnchscpes, and urinary catheters. Sterilizatin f semicritical devices is desirable, but high-level disinfectin is a minimum requirement (Faver and Bnd, 2000). High-level disinfectants may als act as cld liquid sterilants under specific cnditins f use. Therefre, sme prducts may be apprpriate fr bth critical and semicritical devices. Prduct versatility shuld be ne f the cnsideratins fr disinfectant selectin. Nn-critical devices are items that nly cme in cntact with an animal s intact skin, and therefre bear the lwest relative risk f disease transmissin. Stethscpes, tscpes, electrdes, and cmmn animal restraining tls are a few examples f nn-critical devices. Prper treatment f this categry f devices in between animals will depend n the nature and degree f cntaminatin sustained during use. Where cntaminatin is minimal, simple scrubbing with detergent and warm water may be acceptable t assure safety. Hwever, the use f lw- r intermediate-level disinfectants may be apprpriate t assure that disinfectin has been accmplished (Faver and Bnd, 2000). Factrs that Impact Efficacy f Disinfectin Effective disinfectin can nly be achieved if the fllwing interrelated factrs are taken int accunt: Nature f the item r surface t be disinfected Items with smth, nn-prus surfaces are the easiest t disinfect because they can be effectively cleaned f rganic debris and this will allw fr ample surface cntact with the disinfectant applied. As a rule f thumb, the rugher the surface (i.e. crevices, damaged finish), the mre difficult cleaning and subsequent disinfectin will be. T accunt fr this, increased cntact time f the disinfectant r a higher disinfectant cncentratin n these surfaces may be beneficial (careful with increased cncentratins: txicity and crrsive r caustic effects may als be increased).
Cntact time and ther factrs The surface cntact time is the minimum required duratin f expsure f the cntaminated surface t the disinfecting agent in rder t achieve the level f disinfectin that is claimed by the manufacturer. Therefre, careful cnsideratin shuld be given t the manufacturer s recmmendatins and cnditins f use. These recmmendatins will als address ther factrs that may impact efficacy such as ph, water hardness, perfrmance in the presence f rganic debris and ptimal temperatures fr prduct use. Presence f rganic material The presence f rganic material n surfaces t be disinfected will generally cmprmise disinfectin. Any type f cntaminatin will reduce the surface cntact time f the applied disinfectant and therefre its effectiveness. Bld, bld prducts, bdy fluids and feces cntain prteins that will bind and inactivate sme disinfectins r slw their actin. This reinfrces the imprtance f cleaning surfaces prir t disinfectin whenever pssible. If rganic debris cannt be remved, an increased cncentratin f the disinfectant r cntact time may be warranted. Furthermre there are als prducts available that will be effective in the presence f rganic debris. Number and type f micrrganisms present In general, items that have a higher level f micrbial cntaminatin will require a lnger expsure t chemical prducts t achieve disinfectin. Level and type f micrbial cntaminatin may be presumed by the nature f a prcedure that a device was used fr, the health status f the animal, r ther epidemilgical factrs assciated with the veterinary care envirnment. Resistance f micrrganisms Micrrganisms vary in their susceptibility t disinfectants. In general, bligate intracellular bacteria, such as Mycplasma, are the mst susceptible t disinfectin. Gram-psitive and Gram-negative bacteria, envelped viruses and fungal spres are less susceptible, but are nt cnsidered t be resistant t disinfectin. Highly resistant micrrganisms include nnenvelped viruses and mycbacteria. Althugh these rganisms are hearty, they are nt as resistant as bacterial endspres r prtzal cysts and even mre prins, which are resistant t mst disinfectants (Quinn and Markey, 2000). The level f disinfectin shuld be based n the mst resistant micrrganism psing a risk in a given situatin. Type and cncentratin f disinfectant As previusly nted, micrrganisms vary in their verall resistance t disinfectin. Hwever, resistance will als depend n the type f disinfectant used. Each class f chemical prducts acts differently n the cells. It is imprtant t assure that the mde f actin fr the disinfectant is cmpatible fr the type f cells t be destryed. General mdes f actin fr cmmnly used disinfectant classes are addressed in a later sectin f this chapter. Regarding cncentratin, with all ther variables cnstant, the higher the cncentratin, the greater the effectiveness f the disinfectin and the shrter the cntact time (Faver and Bnd, 2000). Hwever, there are exceptins t this rule including alchl and idphrs that have an ptimal range f cncentratin. While the cncept f using cncentrated
disinfectants t achieve faster, mre effective disinfectin may seem like an attractive timesaver, cautin shuld be exercised. Chemical disinfectants are ften hazardus t human and animal health and an increased cncentratin is likely t equate t increased chemical expsure hazard t persnnel, animals and the visiting puplic. Factrs fr Selecting a Disinfectant Because all disinfectants are unique in their chemical actin and prperties, it is unlikely that ne disinfectant will fit all needs. Hwever, fr veterinary care purpses, there are a number f desirable qualities that have been identified and shuld be cnsidered fr prduct selectin. These include (Quinn and Markey, 2000): Wide antimicrbial range Absence f chemical hazards (i.e. txicity, teratgenicity, carcingenicity) Cmpatible with a wide range f chemicals Nn-crrsive Active in the presence f rganic debris Stable at ambient temperatures Lng shelf-life Effective ver wide range f temperatures Inexpensive and readily available Nnplluting and bidegradable In Eurpe, there are a number f rganizatins that test disinfectants fr use in animal husbandry. In Germany, the German Veterinary Medical Sciety (DVG) prvides guidelines fr testing disinfectants and publishes a list f disinfectants that have been tested fr use in animal husbandry. The list als cntains infrmatin n effectivity f the prducts against different categries f pathgens, and suggested cncentratins and incubatin times. Prducts in this list have als been tested under cnditins meant t simulate real life utside the labratry, and include effectivity in a prtein-cntaminated envirnment and n rugher prus surfaces. The Eurpean Cmmittee fr Standardizatin (CEN) is currently establishing Eurpean guidelines fr disinfectant testing in the veterinary field. Overview f Categries f Chemical Disinfectants There are a number f cmpunds that have specific use as disinfectants in the veterinary care envirnment. An verview f the main classes f chemical disinfectants is given in this sectin but peridic cnsultatin t current literature is required as new prducts are cnstantly under investigatin and emerging infectius diseases cntinue t rise. Fr lists f tested disinfectants see e.g. the DVG (German Veterinary Medical Sciety) fr prducts used fr veterinary medicine r in the fd industry r the DGHM (German Sciety fr Hygiene and Micrbilgy) fr disinfectin in human medicine and hspitals. At this time, n general Eurpean lists are available. Alchls Alchls are inexpensive, relatively nntxic, and clrless, and ethyl and isprpyl alchl are mst widely used. They are cnsidered t be intermediate level disinfectants that inactivate rganisms by denaturing prteins. While they are effective fr destructin f envelped viruses and tubercle bacilli, they are less effective against nn-envelped viruses
(particularly isprpyl alchl) and are nt sprcidal (Maillard and Russell, 1997). A cncentratin f 70% f ethyl alchl is mst effective. When used as a surface disinfectant, rapid evapratin f these cmpunds makes sufficient cntact time difficult t achieve. Additinally, alchls tend t harden and swell plastic tubing when used ver time, and may be absrbed by rubber prducts that can lead t irritatin f the skin and mucus membranes (Faver and Bnd, 2000). Aldehydes Frmaldehyde (available in an aqueus 37% slutin) and glutaraldehyde are tw cmmn examples f this class. Frmalin in slutins f 3% - 8% is effective fr intermediate t high level disinfectin. It is less effective than glutaraldehyde in the presence f rganic matter. Despite discussins n ptential carcingenicity, skin irritatin, and irritating fumes, aldehydes are cmmn cmpunds in disinfectant preparatins used in the veterinary field (i.e. breeding, husbandry, transprt and dispsal f all animals). Glutaraldehyde, which inactivates micrrganisms by alkylatin, is als an intermediate t high level disinfectant. At 2% active ingredient, glutaraldehyde slutins are effective against bacterial endspres. Althugh minimally affected by rganic matter, prduct effectiveness is influenced by a number f factrs such as ph and temperature. Glutaraldehyde slutins are mst effective at alkaline ph and effectiveness increases with temperature (Quinn and Markey, 2000). Glutaraldehyde slutins are nncrrsive and are typically used in immersin baths fr high level disinfectin f semi-critical devices (i.e. endscpes) that cannt withstand steam r heat sterilizatin. Due t the txic nature f this cmpund, special cnsideratins must be made fr prper handling and strage f slutins. Immersin baths shuld have tight-fitting lids and be placed in an exhaust hd t minimize persnnel expsure t vaprs. Additinally, t eliminate skin and mucus membrane expsure, splash gggles and apprpriate chemical resistant glves shuld be wrn. Aldehyds shuld nt be used at temperatures belw 10 C. Alkalis Sdium hydrxide (NaOH), r lye is a caustic alkali that has a wide virucidal spectrum when used at a 2 percent cncentratin (prepare by mixing 1/3 cup f NaOH pellets per galln f water careful! ht). This is effective against mst bacteria, and envelped and nnenvelped viruses, althugh smewhat higher cncentratins may be necessary fr sme viruses. This cncentratin is effective against virusesincluding the causes f Avian Influenza, Rinderpest and Pest f Small Ruminants, Newcastle Disease, Malignant Catarrhal Fever, Lumpy Skin Disease and Sheep and Gat Px, African Hrsesickness and Bluetngue, Ft-and-Muth Disease, and Swine Vesicular Disease. Sdium hydrxide shuld nt be used n wd. Sdium hydrxide is als ne f the few cmpunds that can be used fr the inactivatin f prins (in much higher cncentratins) (Taylr, 2000). An verview n deactivatin f prins is given belw. A ph abve 12 is required t fr the inactivatin f bacilli such as Mycbacterium bvis. Chemical expsure risks t persnnel and animals as well as surface incmpatibility are factrs fr the limited use f such prducts. Ammnium hydrxide, a weak base, has a strng activity against cccidial cytes (Williams, 1997). The high ph f even lw aqueus slutins and intense fumes require prtective clthing when using this alkali.
Sdium carbnate, cntaining 0.1% sdium silicate, has significant virucidal activity and is cmmnly used fr the decntaminatin f aircrafts. Biguanides Biguanides are a grup f catinic cmpunds cmmnly used fr hand washing and skin preparatin. Chlrhexidine, a lw-level disinfectant that is incmpatible with aninic cmpunds, is the mst cmmnly used cmpund in this grup. Its activity is ph dependent and it is inactivated by rganic debris (McDnnell and Russell, 1999). It is mre active against grampsitive than gram-negative bacteria and Pseudmnas spec. and Prteus spec. are resistant against chlrhexidine (Widmer and Frei, 1999). Althugh it is active against envelped viruses, it can nt be used against nn-envelped viruses, mycbacteria and mst fungal species, such as dermatphytes, i.e. Micrsprum canis, are resistant (DeBer et al., 1995) Because chlrhexidine has a lnger residual activity n teat skin than mst ther disinfectants, it is widely used fr mastitis cntrl (Quinn and Markey, 2000). Halgens Chlrine Cmpunds Chlrine and chlrine releasing cmpunds, such as hypchlrite, chlrine dixide, sdium dichlriscyanurate, and chlramine-t, are used in sme cuntries fr disinfectin f surfaces, equipment, buildings and vehicles as well as disinfectin f milking installatins and in the fd industry. Sdium hypchlrite (NaOCL r husehld bleach) slutin is an intermediate-level disinfectant when prperly diluted. The mde f actin fr this slutin is dependent n the frmatin f undissciated hypchlrus acid that will xidize peptide links and denature prteins (Maris, 1995). Slutins diuted t final cncentratin must be prepared directly befre use and shuld nt be stred fr mre than 1 day. At a cncentratin f 0.1%, this cmpund is effective against micrbial agents f diseases, including envelped viruses and Ft-and-Muth Disease virus. It can be prepared at the time f use by adding apprximately 30 cc (ml) f husehld bleach t a galln f water (r 1 galln f bleach plus 50 gallns f water). As ph decreases micrbicidal activity (as well as crrsivity) increases. In cncentrated frm chlrine-based disinfectants are usually unstable, and affected by light and heat. They can lse 50% f their cncentratin in a mnth when left in an pen cntainer (Widmer and Frei, 1999). Additinally, the crrsivity f active slutins can be damaging t surfaces and equipment and irritating t the skin and eyes. Bleach slutins are readily inactivated by rganic debris, limiting their effectiveness t situatins where devices r surfaces have been thrughly cleaned prir t disinfectin. In areas heavily cntaminated with secretins, excretins, and sil, there is a cnsiderable rganic demand fr available chlrine and disinfectin shuld be repeated at least nce. Under such circumstances a 3% slutin f sdium hypchlrite shuld prbably be used (3 liters f bleach t 2 liters f water). This cncentratin is effective against a variety f agents f viral diseases including Avian Influenza, Rinderpest and Pest f Small Ruminants, Malignant Catarrhal Fever, Lumpy Skin Disease and Sheep and Gat Px, and African Hrsesickness and Bluetngue as well as ther nn-envelped viruses. At cncentratins used fr water
treatment it is nt effective against Cryptspridium parvum (Fayer, 1995). Halgens rapidly lse efficacy n rugh surfaces such as cncrete. Idine Cmpunds Idine cmpund disinfectants are mre effective in the presence f rganic matter than chlrine cmpunds, and less chemically reactive. Inrganic idine and idphrs, cmpunds in which idine has been cmplexed with plymers t sustain the release f free idine and t increase water slubility, have bth been used fr disinfectin. Hwever, the instability f inrganic idine in the envirnment, skin irritatins, hypersensitivity reactins, and intense staining f cntaminated surface limit its use. At apprpriate dilutins, idphrs are bactericidal, mycbactericidal, spricidal, fungicidal, and virucidal. They are als widely used as teat dips (Saran, 1995). Because the activity f idphrs is greater at a lw ph, the cmpund shuld nt be used in alkaline cnditins r mixed with ther cmpunds. Certain acidified idphr cmpunds that cntain a generic frmulatin f plyethxysubstituted plyprpxy-ethane cmplex are extremely effective disinfectant cmpunds with strng virucidal activity (Maillard and Russell, 1997). The active ingredient must prvide a minimum use cncentratin f 0.02% titratable idine. Organic and Anrganic Acids Acids inhibit the grwth f micrrganisms and a number f cmpunds are cmmnly used as preservatives in the fd industry. Acetic acid has been used fr the treatment f wunds infected with Pseudmnas spec. (Lemarie and hsgd, 1995). The use f acids may be warranted under certain circumstances in the animal care envirnment. Frmic acid is the mst effective f these substances and shuld be used at a cncentratin f 4%. Citric acid, frmic acid, and strng mineral acids, such as phsphric acid, are effective fr inactivating the Ft-and-Muth Disease virus (Quinn and Markey, 2000). Tw mineral acids, hydrchlric acid and sulfuric acid, are smetimes used fr cleaning and disinfectin f animal husing. A 2.5% cncentratin f hydrchlric acid can be used t inactivate endspres f Bacillus anthracis n the skin and is als effective against Rtaviruses and Vesicular Stmatitis virus (Maillard and Russell, 1997). Hwever, the activity f these cmpunds is highly ph dependent and these cmpunds are crrsive and hazardus t wrkers and animals. T minimize chemical expsure risk t persnnel, citric acid shuld be used when pssible. Perxygen Cmpunds Strng xidizing agents such as hydrgen perxide and peracetic acid, have a brad antimicrbial spectrum. Hydrgen perxide is fast acting, nnplluting, and decmpses t xygen and water. Because it is unstable in slutin, stabilizers are usually added. It is bactericidal, fungicidal and virucidal, but shuld nt be used against Mycbacteria (Maillard and Russel, 1997). It is quickly inactivated by prtein cntaminatin f treated surfaces. Peracetic acid is a strng xidizing agent and an even strnger disinfectant that has algicidal, bactericidal, fungicidal, virucidal and spricidal activity. Unfrtunately it can crrde mst metals, rubber and has been suspected t act as a ccarcingen (Sattar and Springthrpe, 1999). Oxidising agents rapidly lse efficacy n rugh surfaces such as cncrete.
Phenlic Cmpunds Phenl is cited in the literature as being the riginal standard against which ther disinfectants were cmpared (Quinn and Markey, 2000). Due t its txicity and unpleasant dr, the use f phenl fr disinfectin purpses has been largely replaced by the use f synthesized phenlic cmpunds. Examples include rth-phenylphenl and rth-benzylpara-chlrphenl. These cmpunds are a cmplex grup f chemicals ften fund in varius cmbinatins and cncentratins in disinfectant prducts. The effectivity f phenlic cmpunds increases with the length f the alkyl chains and number f halgen atms in the mlecule, but this als increases the sensitivity f the cmpunds t rganic material, lwers their water slubility and increases their txicity, s that these cmpunds are nt frequently fund in disinfectants fr veterinary medical use. These prducts are cnsidered t be intermediate t lw level disinfectants. Fr veterinary care purpses, it is imprtant t nte that these cmpunds generally leave a residue n surfaces that may increase chemical expsure fr persnnel and animals. Additinally, pigs and cats are susceptible t the txic effects f these cmpunds (Quinn and Markey, 2000). Als available are substituted phenlic cmpund, that have ptent virucidal activity when prepared as a 1% slutin f stck disinfectant. These types f cmpunds are effective against Eimeria tenella (Williams, 1997) and the viruses f African Swine Fever, Avian Influenza, Hg Chlera, and Velgenic Newcastle Disease, but nt effective against the viruses f Ft-and-Muth Disease and Swine Vesicular Disease (Widmer and Frei, 1999). Quaternary Ammnium Cmpunds (QACs) Quaternary ammnium cmpunds (QACs) are catinic detergents that may be used fr lw level disinfectin, especially surface disinfectin. Benzalknium chlride and ddecyl dimethyl ammnium chlride are cmmn examples f this grup. QACs are relatively nntxic making them apprpriate fr general cleaning purpses. Hwever, QACs are inactivated by rganic debris, metal salts in water (i.e. hard water) and aninic detergents (Heinshn et al., 1995). Even sme gram-negative bacteria, such as Pseudmnas spec., can survive disinfectin with QAC and may grw in QAC slutins. Such limitatins must be cnsidered when develping prcedures fr the use f the prducts in the animal care envirnment. QACS are fund in many disinfectant frmulatins used in the fd industry. Inactivatin f prins Because f the plitical impact transmissible spngifrm encephalpathies have had in the past few years and the public perceptin f these diseases, this paragraph has been included. Prins are characterized by extreme resistance t cnventinal inactivatin prcedures including irradiatin, biling, dry heat, and chemicals (frmalin, betaprpilactne, alchls). While prin infectivity in purified samples is diminished by prlnged digestin with prteases, results frm biling in sdium ddecyl sulfate and urea are variable. Sterilizatin f rdent brain extracts with high titers f prins requires autclaving at 134 C at 3 bar fr 1 h. Denaturing rganic slvents such as phenl r chatrpic reagents such as guanidine isthicyanate r alkali such as NaOH can als be used fr sterilizatin. Prins are inactivated by 1 N NaOH (>1 h), 4.0 M guanidinium hydrchlride r iscyanate, 2,5 % sdium hypchlrite (2% free chlrine cncentratin; >1 h), fllwed by heating in an autclave at 134 C at 3 bar fr >1 h (Annymus, 2003). It is recmmended that dry waste be autclaved at 134 C at 3 bar fr at least 1 hur (depends n the thickness f the material) r incinerated. Large vlumes f infectius liquid waste
cntaining high titers f prins can be treated with 1 N NaOH (final cncentratin) befre autclaving at 134 C at 3 bar fr 1 hur. Dispsable plasticware, which can be discarded as a dry waste, is highly recmmended. Because the parafrmaldehyde vaprizatin prcedure des nt diminish prin titers, bisafety cabinets must be decntaminated with 1 N NaOH, fllwed by 1 N HCl, and rinsed with water. Althugh there is n evidence t suggest that aersl transmissin ccurs in the natural disease, it is prudent t avid the generatin f aersls r drplets during the manipulatin f tissues r fluids and during the necrpsy f experimental animals. It is further strngly recmmended that glves be wrn fr activities that prvide the pprtunity fr skin cntact with infectius tissues and fluids. Frmaldehydefixed and paraffin-embedded tissues, especially f the brain, remain infectius. Cnsideratins fr Disinfectant Use Disinfectant prducts, as well as range f applicatins vary widely. Hwever, careful cnsideratin f manufacturer s prduct infrmatin in cnjunctin with a basic understanding f limitatins t the disinfectin prcess will g a lng way in assuring that disinfectin is an effective part f an infectin cntrl prgram. As previusly addressed, selecting the prper disinfectant fr specific needs is essential. Befre purchasing a prduct, request and review infrmatin frm the manufacturer. Many manufacturers have prduct sheets that will g int mre detail than the infrmatin n the prduct label and may even include efficacy studies that culd impact the decisin-making prcess. Review the material safety data sheet (MSDS) fr the prduct t determine the nature f hazards assciated with prduct use and specific prduct dispsal requirements. Remember that disinfectants are designed t destry living cells. Therefre, all disinfectants are likely t be hazardus in ne way r anther t persnnel and t client animals if the prduct has residual prperties r is imprperly used. Befre disinfecting surfaces r devices, it is essential t clean the surface first if at all pssible. Organic debris can inactivate many disinfectants. Additinally, feces and ther bdy excretins can shield pathgens frm cntact with the disinfectant thus hindering disinfectin. When using a disinfectant, it is essential that the prduct be used in accrdance with the manufacturer s instructins. Nte that the manufacturer s efficacy claims are based n its prescribed dilutin rati, methd f preparatin, methd f applicatin, surface cntact time and shelf-life. T clarify, cntact time is the minimal amunt f time that a prduct must be in cntact with the surface t be disinfected in rder t achieve the level f disinfectin claimed by the manufacturer. Shelf-life is the amunt f time that a diluted prduct is actively effective fr use nce prepared frm a cncentrated prduct. There are a number f rganizatins in Eurpe that prvide lists f disinfectants fr use in animal husbandry, human medicine, and the fd industry. Examples are the German Veterinary Medical Sciety (DVG), and the Germany Sciety fr Hygiene and Micrbily (DGHM). These lists can be cnsulted fr cmmercial disinfectant preparatins that can be used in certain situatins and against different types f pathgens. Under circumstances where it is critical t assure that disinfectin practices are efficacius, (i.e. infectius disease utbreaks, immunsuppressed animal husing), it may be beneficial t perfrm a surface cntaminatin test. There are several techniques described in the
literature that may be used fr surface testing (Tamasi, 1995). The flr may be the surface f chice fr such a test because it is likely t receive the mst cntaminatin f the envirnmental surfaces, and this surface ften has irregularities that will make disinfectin a challenge. In cases f disease utbreaks, disinfectin prcedures may be dictated by law and clse cperatin with veterinary authrities may be necessary. Summary Cleaning and disinfectin are a majr cmpnent f disease preventin and eradicatin in every zlgical exhibitin. Despite the develpment f antimicrbial drugs and effective vaccines, infectius diseases remain a majr threat t animals kept in captivity as well as ur wildlife ppulatin. The prper selectin and prper use f disinfectants requires extensive knwledge nt nly abut the effectiveness f specific disinfectant cmpunds, but als abut the infectius agent, the cnditins under which the disinfectant will be used and the side effects f each cmpund, including txic, caustic and crrsive prperties. Hwever, disinfectin is nly ne aspect f an effective infectius disease cntrl prgram in any animal r human health envirnment. As described in this chapter prper sanitatin cnsists f multiple cmpnents in additin t cleaning and disinfectin. Insect and vermin cntrl, and prper fd strage, handling, preparatin and distributin are equally imprtant fr a healthy z envirnment. Furthermre, sanitatin shuld be part f a preventive veterinary medicine prgram that wuld further include training f persnnel, prper nutritin and feeding, rutine surveillance and prphylactic medicine including vaccinatin, quarantine f new and sick animals, prper hlding facilities, crrect dispsal f waste prducts and dead animals. This chapter can nly prvide a brief verview f the guidelines f cleaning and disinfectin. Befre using a disinfectant, the manufacturer s label shuld always be studied. When dealing with a specific disease prblem, further infrmatin regarding disinfectin can be fund in the disease specific fact sheets. Additinally, the listed references will prvide mre detailed infrmatin.
References Annymus 2003. Beschluss 603 des Ausschusses für Bilgische Arbeitsstffe: Schutzmaßnahmen bei Tätigkeiten mit Transmissibler Spngifrmer Enzephalpathie (TSE) assziierten Agenzien in TSE Labratrien. BarbBl. 2003-3. Pp. 55 Deutsche Veterinärmedizinische Gesellschaft (DVG). Frankfurter Str. 89, 35392 Giessen, Germany. www.dvg.net. Deutsche Gesellschaft für Hygiene und Mikrbilgie (DGHM). Institut für Hygiene und Mikrbilgie, Univeristät Würzburg, Jsef-Schneider-Str. 2, 97080 Würzburg, Germany. www.dghm.rg. Blck, S. 2000. Definitin f terms. In: Blck, S. (ed). Disinfectin, sterilizatin and preservatin. 5 th ed. Lippinctt Williams & Wilkins, Philadelphia. Pp. 19-28. Bthe, H. W. 1998. Antiseptics and disinfectants. Vet. Clin. Nrth Amer.: Small Anim. Pract. 28: 233-248. DeBer, D. J., K. A. Mriell, and R. Cairns. 1995. Clinical update n feline dermatphytsis: part II. Cmp. Cnt. Edu. Prac. Vet. 17: 1471 1480. Bruins, G., and J. A. Dyer. 1995. Envirnmental cnsideratins f disinfectants used in agriculture. Rev. Sci. Tech. 14: 81-94. Faver, M., and W. Bnd. 2000. Chemical disinfectin f medical and surgical materials. In: Blck, S. (ed). Disinfectin, sterilizatin and preservatin. 5 th ed. Lippinctt Williams & Wilkins, Philadelphia. Pp. 881-917. Fayer, R. 1995. Effect f sdium hypchlrite expsure n infectivity f Cryptspridium parvum cysts fr nenatal BALB/c mice. Appl. Envirn. Micrbil. 61: 844 846. Ftheringham, V. J. C. 1995. Disinfectin f livestck prductin premises. Rev. Sci. Tech. 14: 191 205. Fwler, M. E. 1978. Sanitatin and Disinfectin. In: Fwler, M. E. (ed). Z and Wild Animal Medicine. W. B. Saundres, Philadelphia. Pp. 21-30. Heinshn, P., R. Jacbs, and B. Cncby. 1995. (eds) Bisafety Reference Manual, 2 nd ed. Fairfax: American Industrial Hygiene Assciatin. 101-110. Heuschele WP. 1995. Use f disinfectants in zs and game parks. Rev. Sci. Tech. 14: 447-454. Jarrll, E. L. 1999. Sensitivity f prtza t disinfectants: intestinal prtza. In: Russell, A. D., W. B. Hug, G. A. J. Ayliffe (eds). Principles and practice f disinfectin, preservatin, and sterilizatin, 3 rd ed. Blackwell Scientific Publisher, Oxfrd. Pp. 251-257. Jeffrey, D. J. 1995. Chemicals used as disinfectants: active ingredients and enhancing additives. Rev. Sci. Tech. 14: 57-74.
Lemarie, R. J., and G. Hsgd. 1995. Antiseptics and disinfectants in small animal practice. Cmp. Cnt. Edu. Prac. Vet. 17: 1339 1350. Maillard, J. Y., and A. D. Russell. 1997. Viricidal actin and mechanisms f actin f bicides. Sci. Prg. 80: 287 315. Maris, P. 1995. Mdes f actin f disinfectants. Rev. Sci. Tech. 14: 47-55. McDnnell, G., and A. D. Russell. 1999. Antiseptics and disinfectants: activity actin and resistance. Clin. Micrbil. Rev. 12: 147 179. Quinn, P., and B. Markey. 1999. Viricidal activity f bicides. activity against veterinary viruses. In: Russell, A. D., W. B. Hug, G. A. J. Ayliffe (eds). Principles and practice f disinfectin, preservatin, and sterilizatin, 3 rd ed. Blackwell Scientific Publisher, Oxfrd. Pp. 187 196. Quinn, P., and B. Markey. 2000. Disinfectin and disease preventin in veterinary medicine. In: Blck, S. (ed). Disinfectin, sterilizatin and preservatin. 5 th ed. Lippinctt Williams & Wilkins, Philadelphia. Pp.:1069-1103. Ruan, M. 2001. Efficacy cmparisns f disinfectants used by the cmmercial pultry industry. Avian Dis. 45:972-977. Russell, A. D., 1996. Activity f bicides against mycbacteria. J. Appl. Bact. 81: 87S - 101S. Russell, A. D., 1998. Micrbial susceptibility and resistance t chemical and physical agents. In: Cllier, L., A. Balw, M. Sussman (eds). Tpley and Wilsn s micrbilgy and micrbial diseases, 9 th ed. Arnld, Lndn. Pp. 149-184. Russell, A. D., 1999. Antifungal activity f bicides. In: Russell, A. D., W. B. Hug, G. A. J. Ayliffe (eds). Principles and practice f disinfectin, preservatin, and sterilizatin, 3 rd ed. Blackwell Scientific Publisher, Oxfrd. Pp. 149-167. Russell, A. D., V. S. Yarnych, and A. V. Kulikvskii (eds). 1984. Guidelines n Disinfectin in Animal Husbandry fr Preventin and Cntrl f Zntic Diseases. Wrld Health Organizatin (Veterinary Public Health Unit), Geneva, Switzerland. Rutala, W. 1996. APIC guidelines fr selectin and use f disinfectants. Am. J. Inf. Cntr. 24: 313-342. Saran, A. 1995. Disinfectin in the dairy parlur. Re. Sci. Tech. 14: 207 224. Sattar, S. A., and S. Springthrpe. 1999. Viricidal activity f bicides: activity against human viruses. In: Russell, A. D., W. B. Hug, G. A. J. Ayliffe (eds). Principles and practice f disinfectin, preservatin, and sterilizatin, 3 rd ed. Blackwell Scientific Publisher, Oxfrd. Pp. 168 186. Seymre S. Blck. 2001. Disinfectin, Sterilizatin, and Preservatin. 5th Ed. Lippinctt, Williams, & Williams, Philadelphia, Pa.
Springthrpe, S., and S. A. Sattar. 1990. Chemical disinfectin f virus-cntaminated surfaces. In: Straub, C. P. (ed). Critical reviews in envirnmental cntrl. Vl. 20. CRC Press, Bca Ratn, Flrida. Pp. 169-229. Stellmacher, W. 1966. The Testing f Heavy-Duty Disinfectants Against Bacteria. Natinal Veterinary Medicine Testing Institute, Berlin, Pp. 547-575. Stne, S.S., and W.R. Hess. 1972. Effects f sme disinfectants n African swine fever virus. Appl. Micrbil., 24: 115-122. Tamasi, G. 1995. Testing disinfectants fr efficacy. Rev. Sci. Tech. 14: 75-79. Taylr, D. M. 2000. Inactivatin f transmissible degenerative encephalpathy agents: a review. Vet. J. 159: 10-17. WHO/CDS/CSR/APH/2000.3, 1999. Reprt f a WHO cnsultatin: WHO Infectin Cntrl Guidelines fr Transmissible Spngifrm Encephalpathies, Geneva, Switzerland, March 23-26, Annex III. Widmer, A. F. and R. Frei. 1999. Decntaminatin, disinfectin and sterilizatin. In: Murray, P. R., E. J. Barrn, and M. A. Pfaller (eds). Manual f clinical micrbilgy. ASM Press, Washingtn, DC. Pp. 138 164. Williams, R. B. 1997. Labratry tests f phenlic disinfectants as cysticides against the chicken cccidium Eimeria tenella. Vet. Rec. 141: 447 448.
Table 1: Effectiveness f classes f disinfectants against varius pathgens Class f Disinfectant Alchls Aldehydes Alkalis Biguanides Halgens Organic and Anrganic Acids Perxygen Cmpunds Phenls QAC Infectius Agent Chlrine Cmpunds Idine Cmpunds bligat intracellular gram-psitive Bacteria gram-negative bacilli endspres Fungi including spres Viruses envelped nn-envelped Prtza including zysts Prins highly effective effective limited effectiveness nt effective This table prvides nly a general verview f the effectiveness f varius classes f disinfectants. The effectiveness f a specific cmpund in each f these classes may vary. Fr mre detailed infrmatin please review the infrmatin prvided in the text. Always cnsult the manufacturers label fr crrect use and cncentratin f each cmpund. The table is based n the fllwing surces: Bthe, 1998; Bruins and Dyer, 1995; Jarll, 1999; Jeffrey, 1995, Lemarie and Hsgd, 1995; Maillard and Russell, 1997; McDnnell and Russell, 1999; Quinn and Markey, 1999 and 2000; Russell, 1996, 1998 and 1999; Sattar and Springthrpe, 1999; Sringthrpe and Sattar, 1990; Taylr, 2000; Widmer and Frei, 1999; Williams, 1997.