There are many disinfectants to choose from but they basically fall into a few categories based on their active ingredients and abilities to kill different micro-organisms. Many parent compounds have been made more effective, stable, and less irritating by the addition of other chemical groups. Therefore it is not appropriate to generalise the activity of a parent compound, such as iodine or phenol, upon the commercial derivatives available. Each commercial formulation is tested using standard procedures and it is the result of these tests that should form the basis of selection.
The concept of developing a policy for the selection and application of chemical disinfectants was first introduced for hospitals (Gardner and Peel, 1986). The selection of a type or brand of disinfectant should be based on the type of organism we wish to control, the surface/object involved, risk or harm to the user or animal and finally cost-effectiveness if two products appear to be similar in other respects.
Based on the pathogenic micro-organisms found in a psittacine breeding operation the brand of disinfectant for baby brooders and feeding syringes should be a safe bactericide product with some fungicide and viricide properties as well. The disinfectant for cage wire, walls and floors should be an effective viricide which is least affected by the presence of organic matter.
Chlorine compounds are traditionally popular disinfectants because of their rapid killing ability against many microorganisms and low cost (Gangle, 1988). They are among the most potent sporicides and are also lethal to both lipophilic and hydrophilic viruses.
Common house-hold bleach is the traditional form of chlorine. For even large indoor areas the vapors produced as bleach dries can be quite irritating especially for birds with their efficient respiratory system. Other negatives are its corrosive nature, especially on cage wire and its decrease in activity by even small amounts of organic matter.
A new form of sodium chlorite is reported to have a wide microbicidal activity and low toxicity to man and animals (Alcide, Alcide Corp) but it is expensive and not readily available. Alcide is a two-component sodium chlorite base:organic acid activator compound which are sold separately and once mixed together with water is active for about 14 days. This solution when applied as a spray or vapour was found to have a sporicidal effect after 15-30 minutes where-as a mixture of glutaraldehyde and formaldehyde were only sporistatic when applied this way (Wallace et al., 1988).
Free iodine has rapid lethal effects against bacteria and fungi but can be an irritant, tends to be toxic and is sparingly soluble in water (Russell and Hugo, 1987). However iodophores are compounds in which the iodine is “tamed” and are probably the safest of all disinfectants to use. They retain the germicidal action, but not the undesirable properties of iodine.
Iodophores are effective against a broad range of bacteria and fungi and their spores. They are also a good viricide but only after prolonged exposure. They remain active in the presence of organic matter provided that the pH does not rise above 4 (Russell and Hugo, 1987).
Chlorhexidines have some limitations which makes their routine use questionable. Although less toxic than phenol and aldehyde disinfectants it is not effective against several types of bacteria. In an outbreak of herpes virus some recommend the addition of chlorhexidine (20ml per gallon) to the drinking water to slow the spread of the disease (Clubb, 1989). This assumes that spread is by ingestion however breathing in the organism may also occur.
When we used a chlorhexidine brand as a soak for our hand-feeding syringes we had an outbreak of pseudomonas infection in our babies. We actually cultured the bacteria from the soak water, the surface of the syringes and from our brooder water. Pseudomonas grows well in standing water and chlorhexidine is ineffective against it. This contra-indicates the use of chlorhexidines in circumstances where moist conditions occur such as brooders and incubators. We now add salt to our brooder water (1/4 cup per gallon) and have found this to be very effective in reducing the growth of organisms.
Some breeders report adding chlorhexidine to their hand-feeding food to prevent or control Candida infections (Clipsham, 1988). Sour crop is usually related to a poor food formulation or a systemic infection which has resulted in a slow down in gut transit. Diets that either contain too many simple sugars or have poor water holding qualities may contribute to the problem by providing food for the Candida and further slowing down gut passage. It would be more logical to switch foods than continuously expose babies to chlorhexidine, a possible carcinogen.
Quaternary Ammonium (Quats)
Quats are cationic surfactants with strong bactericidal but poor sporicidal properties (Russell and Hugo, 1987). They are questionable fungicides and their germicidal activity is suppressed in the presence of organic matter.
Quaternary ammonium compounds make good general cleaners and do provide some preliminary destruction of disease-causing organisms. They are not widely used on farm sites because of the large amount of organic debris.
Phenolics are considered some of the strongest disinfectants and are acceptable for use in USDA supervised quarantine stations. They kill fairly quickly, within 10 minutes, and retain their effectiveness in the presence of organic matter better than most other disinfectants.
Phenolic derivatives, such as ortho-phenylphenol, are more effective as disinfectants. Common substitutions to the phenolic group are chlorine para- (4) and benzyl ortho- (2) . These derivatives increase the bactericidal and viricidal activity of phenol (Russell and Hugo, 1987).
Synthetic detergents have also been added to formulations of phenolics, increasing detergency (Prindle, 1983). This allows some brands to be used in a single application, cleaning and disinfecting at the same time.
Phenolics are potent bactericides, killing a broad range of disease-causing bacteria including Pseudomonas and Salmonella. Bacterial spores seem to be resistant to phenols. They are very effective against lipophilic or enveloped viruses but may have some limitations against other viruses. However the most commonly encountered parrot viruses, herpes and pox, plus another the paramyxoviruses, are enveloped viruses.
Phenolics are especially useful for cage wire and floor disinfection, and in footbaths. When used in foot baths or heavily soiled areas the diluted solution strength can be increased 3 to 4 fold.
Some products available are a combination of two or more compounds that are compatible and cooperative in action. They have been developed to broaden the spectrum of activity, increase residual action or add detergency.
One such product is LysofumeTM (Winthrop) which contains both a formaldehyde and quaternary ammonium compound.
Many compounds are incompatible and only premixed products should be used.
Aldehydes are some of the most effective biological killing agents with good resistance to organic matter inactivation. They are effective against most types of bacteria, bacterial spores, fungi, and viruses. They also provide residual activity on surfaces where they are allowed to dry.
One unique product, LysofumeTM (Winthrop), is a vapour-phase surface disinfecting fumigant which slowly decomposes yielding formaldehyde. In LysofumeTM the formaldehyde is trapped in solution thus significantly reducing the toxicity associated with formaldehyde gas. When applied to surfaces a level of 6-8% formaldehyde activity around the film coating is created until the active ingredient is fully decomposed. The rate of decomposition increases with an increase in temperature thus cold water should only be used.
The sporicidal activity of these compounds appears to be confined to situations where the object to be treated can be soaked in the solution (Wallace et al., 1988).
Glutaraldehyde is significantly more expensive than other disinfectants and is usually supplied already diluted at the use concentration of 2%. It may only be required when non-enveloped viruses or bacterial spores are of concern. These viruses include parvovirus, papillomavirus and reovirus. Glutaraldehyde is often used as a cold sterilization solution for utensils and endoscopes.
Safety and Toxicity
The recommended diluting instructions for each product must always be followed. Products should not be mixed as chemical incompatibilities may cause an increase in toxicity and/or decrease in effectivness. Some products when mixed together produce reactions that release toxic fumes. Chlorine gas from bleach is especially dangerous.
Some manufacturers make claims such as “non-toxic, non-injurious, non-irritating, non-corrosive and 100 % biodegradable”, for their water diluted products. These claims are based on tests with diluted solutions at the recommended use levels, usually 1:128 or 1:256. An American Veterinarian seems to go along with this for one of the strongest disinfectants a glutaraldehyde product (Cilpsham, 1988).
However when you read the fine print under the “Danger” and “Precaution” headings on the concentrate of these products it usually states “harmful if swallowed, avoid skin contact, wear rubber gloves and shield eyes with goggles or face shield, probable mucosal damage may result, corrosive”. Perhaps this contradiction is justified with the belief that dilution eliminates the toxicity. However its advisable to follow the precautionary statements made for the concentrate even when using the diluted disinfectant, as some labels recommend. This is especially important for the phenolics and aldehydes which are particularly irritating to skin.
There may be adverse effects with these chemicals after long term use, for both the person applying the agent and the animals. Also of concern are the environmental consequences of these chemicals entering the water table due to improper waste water removal although many of these products are biodegradable.
Mandl et al. (1987) studied the efficacy of various disinfectants on broiler breeder eggs contaminated with salmonella. No adverse effects on hatchability were obtained when hatching eggs were soaked in 2 % solutions of aldehydes, phenols or quaternary ammonium compounds for five minutes. Hatchability was significantly reduced by a 5 % solution of an iodophor compound. The most effective treatment of hatching eggs contaminated with Salmonella was submersion in hot water (600C) for one minute followed by five minutes in an aldehyde/phenol disinfectant (Mandel et al., 1987).
The use of good sanitation and isolation practices can be the best insurance in preventing infectious diseases in aviaries. Its unfortunate that vaccines are not yet available for most of the viruses which parrots are susceptible to. But even when they are, a thorough sanitation program will still be an important part of disease control.
General cleanliness and professional management is the first step in minimizing a viral outbreak in our aviaries. Excreta must be removed from indoor facilities as often as necessary to prevent disease of the birds from cross-contamination.
For routine germicidal cleaning of incubator, brooder, feeding and watering equipment less irritating products such as iodophores and quats can be used. When cage disinfecting or if viruses are thought to be present the use of a phenolic or aldehyde based product provides the greatest assurance that thorough, if not complete, disinfection is achieved.
A good working relationship is needed between the aviculturist, an experienced avian veterinarian and a post-mortem laboratory. This aids in establishing a disease prevention program geared towards the particular circumstances of each facility with quicker responses to disease problems.
Part 3: Refernces/ Appendix 1 & 2
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