Quarantine and Disinfection
By Abrahm Simons
Zoos and hobbyists interested in providing the best care they can for their animals must use quarantine procedures when adding new animals to their collections or caring for sick animals. Not having the resources that a zoo does, the hobbyist must make do with the tools at their disposal. All new amphibians brought into the home, as well as ill animals and certain food items such as live fish, should be quarantined.
Why should I quarantine?
When new amphibians are brought into a home with established amphibians, both new and old animals may be at risk. If purchased, even the most reputable seller may unwittingly sell animals that are carrying a possibly fatal disease. This concern, however, applies to any animals new to the collection obtained from any source. Quarantine allows the hobbyist to observe the animal(s) prior to introduction into an established collection. Some things to observe for include: Does it show any signs of illness? Does the skin appear free of external parasites? Does it act and move normally? Is it acclimating and eating?
There is also a secondary benefit of quarantine: the newly acquired amphibians are able to acclimate to their new environment without other sources of stress. Limiting stress is essential in that stress can lower an animal's immune response: a lowered immune response decreases an animal's ability to naturally fight disease. Amphibians from different geographical regions may carry different sets of bacteria, parasites, viruses or fungus that they carry without symptoms, but which may cause disease to an amphibian from a different area. Quarantine allows newly acquired (and probably stressed) animals to not be exposed to these pathogens and vice versa. Even if the animals are from the same species, quarantine allows newly acquired animals to recover (shipping is especially stressful) by avoiding the stress of other animals.
Animals that become ill should also be quarantined. This will limit the spread of the disease among other animals in the collection. Quarantine should also provide a low stress environment that makes treating the amphibian simple and painless while allowing the caretaker to carefully observe the animal.
How do I quarantine my new caudates?
Animals in quarantine should ideally be kept in a separate room from other animals. If this isn't possible, the quarantined animals should be kept as far as possible from others. The air in the room can transfer pathogens. Aquatic diseases can be spread by tiny droplets of water formed by the bubbling of splashing of filters. Having the animals in the same physical location also increases the risk of mistakes being made as splashes, or the chance that clothing or misplaced supplies can transfer disease causing organisms. The quarantine area should have low traffic with minimal lighting and limited exposure to loud noises and other threatening stimuli.
When completing normal maintenance, work with healthy or resident animals before treating the quarantined. This way if any germs are transferred, they will be moving from the known healthy animals to the suspect animals. The use of alcohol based hand washes or a thorough soap and water cleaning on the hands will help minimize disease spread between the two groups. Not all pathogens will be killed with this treatment. Disposable vinyl or nitrile gloves, available at most pharmacies and home improvement stores, will also help control disease if changed between working with animals. Combining disposable gloves with hand washing between animal groups will be very effective. Gloves are known to cause problems in amphibians, so they should be rinsed thoroughly before use, and contact with animals should be minimized. Gloves are most useful in this situation as a way to minimize transfer of pathogens and so should be removed without skin contamination and disposed of after working with any group of animals.
When quarantining animals, it often best to use minimalistic enclosures. Plastic shoe boxes and sweater boxes make excellent quarantine facilities. They are easy to disinfect after use and can be disposed of if necessary. If possible tubs made out of food grade plastic would be best as they are unlikely to leach any toxic compounds into the water or substrate. If at all possible house all quarantined animals in separate enclosures to limit conspecific aggression and other stresses. Substrate should be simple unbleached paper towels that have been moistened. Hides should be made of nonporous material that can be easily sterilized after the quarantine period, or can be discarded after use. Schedule 40 PVC pipe pieces make excellent hides. This combination of simple substrate, furnishings, and enclosure make monitoring of feeding, defecation and other behaviors easy. Care should still be taken to provide the amphibian with an enriching enclosure that will make the animal feel secure.
Separate supplies should be used for care of animals in quarantine. Nets, siphons or other supplies may become contaminated by contact with water, substrate or quarantined animals. The fungus that causes chytridiomycosis, Batrachochytrium dendrobatidis, remains infectious in distilled water for up to four weeks. Bacteria species can form hardy spores and survive extremely harsh conditions. Best practice would involve having two sets of materials or disinfecting all materials after use. Please see notes on disinfection below.
Great care should also be taken with feeder animals. If at all possible do not use feeder insects that may easily escape or enclosures that are not designed to prevent their escape. Insects or other highly mobile feeder animals may transfer pathogens from enclosure to another or between the quarantine room and the normal collection. Ventilation should be blocked off by meshes appropriate to the size of feeder insect used and periodically checked for damage. Crickets are well known for destroying meshes and escaping.
How long should I quarantine?
To be effective, the quarantine should last enough time for any infections to progress to a disease state where they can be identified and treated. In general the longer the quarantine that can be provided, the more effective it will be in preventing spread of infection. A bare minimum of 30 days is usually recommended with 90 days being even better. When in doubt, hold the animals in quarantine for a longer period of time.
If possible, fecal examinations and chytridiomycosis testing could be used as criteria for ending quarantine. At least 30 days should still be taken to reduce the risk of bacterial, viral or fungal infections with long incubation times.
Disinfection, Sterilization and Cleaning
Cleaning is distinctly different from disinfection or sterilization. What the average person thinks of as cleaning is not sufficient when working with pathogens. Typical household cleaners such as dish or hand soap are not disinfectants and will leave many disease causing organisms behind.
Disinfection is the reduction of microbes generally to a low level where organism load is insufficient to produce disease. Sterilization is the complete killing of all organisms. Sterilization will be nearly impossible in the home, but disinfection is well within reach.
- Bleach - The most common household disinfectant is bleach. The active ingredient of bleach is sodium hypochlorite. Bleach dilutions should be prepared immediately before use, as the chlorine will dissipate, and it will be only half as effective after sitting for two hours. Bleach solutions should be 1:10 (0.5% active ingredient) dilutions from the concentrated stock that is purchased at stores. It should be noted that organic material rapidly inactivates bleach, so excess dirt, blood, leaves, and other similar matter should be removed before disinfecting, or the bleach will not be effective. Bleach should be left in contact with the surface to be disinfected for at least 15 minutes but exposures of up to 30 minutes should be used for supplies known to be contaminated. Bleach should only be used to treat non-porous items and everything should be rinsed thoroughly after treatment. The use of a dechlorinating agent (as used for tap water) is highly recommended in conjunction with rinsing to aid in removal of residual chlorine. The use of bleach around occupied enclosures should be minimized to prevent the poisoning of animals by accidental splashes and gases produced by the bleach.
- Acetic Acid/Hydrogen Peroxide Mix - Another useful and important disinfectant system is composed of two separate components: 3% hydrogen peroxide and 5% acetic acid. The hydrogen peroxide used is the typical over the counter product found at pharmacies. Acetic acid at 5% is the composition of common white vinegar. The two chemicals are placed into two different spray bottles and applied to the surface simultaneously and allowed to sit 10-15 minutes before wiping dry. Hydrogen peroxide is light and air sensitive. It should be stored in an opaque, air tight bottle when not in use. Hydrogen peroxide left in the spray bottle will become inactive.
- Alcohols - Alcohols also make fine disinfectants for surfaces. Of the many alcohols, the two most commonly used are ethanol and isopropanol. Ethanol, or ethyl alcohol, that is to be used as a cleaning agent should be of drinking grade and at least 70% alcohol by volume. Ethanol for topical use in humans is denatured, meaning it has small quantities of toxic compounds, such as methyl ethyl ketone, added to prevent oral consumption; it should be avoided. Isopropanol, also known as isopropyl alcohol, 2-propanol and rubbing alcohol, is easily obtained at drug stores and is a suitable surface disinfectant. Drinking ethanols are usually a corn ethanol in the US. Alcohols that are used for disinfectant purposes should be 70% by volume. Lesser or greater concentrations are less effective and should be avoided. Spray liberally over the surface to be disinfected and allow to evaporate. Contact time should be 15 minutes, and reapplication may be necessary. Alcohols are best used as surface disinfectants, to clean non-porous surfaces such as countertops. It should be noted that ethanol may have an adverse affect on adhesives and may cause cracking, hardening or misshaping of some rubbers. Alcohols dry out the skin and compatible gloves would be advised for their use.
- Ammonia - Household ammonia that is purchased without deodorants, colorants or detergents will also work well as a disinfectant. Concentrations of 5% to 10% of the bottled solution should be used. As with bleach, the surfaces should be exposed for at least 15 to 30 minutes for those that are known to be contaminated. Ammonia should also not be used around inhabited enclosures because of the danger posed by fumes and accidental exposure. Ammonia based products and bleach based products should never be mixed, as they can quickly evolve large quantities of deadly gases.
Natural substrates such as earth, loam, potting soil, leaf litter and coconut coir (Bed-A-Beast, etc) can be disinfected by heating. Place in an oven that is at least 160°F (70°C) for 20 minutes or longer. Other natural decorations and hides may also be treated by heating to 160°F for at least 20 minutes but it should be noted that larger pieces such as branches may take longer to reach an internal temperature of 160°F.
Rocks, gravel, pots, bricks and other similar materials can be disinfected by boiling. It should be noted that materials should be heated from room temperature to a boil. Adding rocks to hot water can be very dangerous.
Brown, Robert K., et al. Facility Design and Associated Services for the Study of Amphibians. Institute for Laboratory Animal Research.
Brock, Brent, et al. Amphibian Steward Network: Procedures and Guidelines. Treewalkers International.
Cashins, et al. The Lethal Effect of Latex, Nitrile and Vinyl Gloves on Tadpoles. Herpetological Review 39(3):298 September 2008. Available from ResearchGate.
Crawford, Lauren, et al. A Comparison of Commonly Used Surface Disinfectants Alcohol-, Phenol-, Chlorine-, and Quaternary Amine-Based Disinfectants. Infection Control Today [serial online], November 2000. http://www.infectioncontroltoday.com/articles/2000/11/a-comparison-of-commonly-used-surface-disinfectan.aspx [no longer available online].
Johnson, M.L. and Speare, R. Survival of Batrachochytrium dendrobatidis in Water: Quarantine and Disease Control Implications. Emerging Infectious Diseases [serial online], August 2003. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3020615/
Pasmans, F., et al. Introducing Reptiles into the Captive Collection: The Role of the Veterinarian. The Veterinarian Journal.
Stouffer, Judy. 1999. Vinegar and Hydrogen Peroxide as Disinfectants. Online article, accessed July 2010.
© 2010 Abrahm Simons