Infectious diseases in shelter situations and their management
edt August 15, 2015
The Prevention of infectious diseases in cat shelters guidelines that this article is updating were published in J Feline Med Surg 2013; 15: 546-554; the update has been compiled by Karin Möstl.
In shelter situations, infectious diseases are difficult to prevent and they spread quickly.1 In addition, shelters are unstable biological environments; not only disease outbreaks are frequent, but also new pathogens may emerge or virulence variants of endemic pathogens may occur, as a result of rapid transmission cycles and consequent agent evolution. The virulent systemic feline calicivirus infection is a point in case.2
The ABCD guidelines describe the most important factors to minimise the spread of infectious agents.1 These include housing in individual sections (quarantine pens for incoming cats, isolation facilities for sick or potentially infectious cats, accommodations for healthy, FIV- and FeLV-negative cats, for pregnant and lactating queens and their kittens), testing for infectious agents, hygiene measures and stress reduction.
Stress is reduced above all by allowing for low animal densities, by providing environmental enrichment like beddings, scratch posts, toys and hiding areas. Newly sheltered cats provided with a hiding box during quarantine had significantly lower stress levels compared to cats without this enrichment.3 Animal handling, like stroking anxious cats may have positive effects, as suggested by an increase of S-IgA and reduction of upper respiratory tract disease.4
Synthetic pheromones have been used in shelters with the objective to reduce stress. They are expected to alter the emotional state of the cat via the limbic system and the hypothalamus and have been recommended against anxiety-related behaviours, such as house-soiling.5 Horwitz and Pike6 have published anecdotal observations that synthetic pheromones are useful when introducing new cats into a household. However, these data have not been corroborated by impartial, controlled studies. But, based on reports about their use in the treatment of undesirable stress-related behaviour, they may be considered in addition to other stress-reducing measures.
3 Vinke CM, Godijn LM and Van der Leij WJR. Will a hiding box provide stress reduction for shelter cats? Applied Animal Behaviour Science 2014; 160: 8693.
4 Gourkow N, Hamon SC and Phillips CJC. Effect of gentle stroking and vocalization on behaviour, mucosal immunity and upper respiratory tract disease in anxious shelter cats. Preventive Vet Med 2014; 117: 266-275.
This guideline concerns only rescue shelters, although hygiene aspects will also apply to other situations. ABCD recognises that there is a wide variation in the design and management of shelters, which largely reflects local financial constraints. The guidelines have been written with this diverse audience in mind; they point to the ideal situation, and suggest compromise where this ideal cannot be attained. Furthermore they focus on recommendations with regard to infectious diseases.
Rescue shelter: where cats are kept temporarily until a new guardian is found or euthanasia performed. ABCD emphasises that keeping cats in shelters should be avoided whenever possible. Where other arrangements can be made, cats should not enter rescue shelters. This is a reflection of the inevitable stress and risk of infection associated with movement to this type of accommodation. However where necessary, then good practice should be adopted to minimise these side effects.
Boarding catteries: where cats are put temporarily while their guardians are on vacation or business
Multicat pet households: where intentionally more than one pet cat is kept
Cat sanctuaries: where rescued cats are kept until they die
Breeding catteries: where cats are intentionally bred
Trap, neuter and return cat colonies: where cats roam freely with or without permanent carers
In shelter situations, infectious diseases spread frequently and quickly; they are difficult to prevent for the following reasons:
In many cases, all incoming cats are accepted.
Cats may be persistently / latently infected with infectious agents.
Newly accepted cats reside alongside long-term residents.
Often a no-kill policy is enforced.
Stress, poor nutrition etc. facilitate spread of infectious agents and development of disease.
Shelters are often short of money, resulting in crowding, inadequate hygiene and vaccination, and no testing for infectious diseases.
Persons who work in shelters are highly motivated but usually untrained in hygiene and disease management; the local veterinary surgeon is often responsible for such training.
A preventive management program should be implemented that considers possible routes of infection and keeps the circulation of pathogens as low as possible. Measures include the regulation of housing conditions, quarantine, good husbandry, testing for infectious diseases, vaccination, good hygiene management and stress reduction.
Good building design can aid infectious disease control. Compartmentalisation of the shelter into individual sections can facilitate containment of a disease outbreak, should it occur. In general four separate areas are required:
a quarantine area for incoming cats,
isolation facilities for sick or potentially infectious cats,
accommodation for healthy, FIV and FeLV negative cats,
accommodation for pregnant and lactating queens and their kittens.
In state-of-the-art shelters, all cats are essentially in quarantine. Under less than ideal conditions, cats should be kept in quarantine for a minimum of 3 weeks (considering cats incubating FPV or FCV infections or reactivating latent FHV infections, and while their vaccination becomes effective). Considering the risk of FIV and FeLV infections, where all incoming cats are routinely screened (e.g. in high risk areas), quarantine should not be shorter than 6 weeks (the period for FIV seroconversion and for becoming FeLV antigenemic may be long). Cats showing any signs of infectious disease should be moved immediately to the isolation facilities.
Cats showing signs of infectious disease or testing positive for e.g. FeLV must be isolated. Isolation areas have to be strictly separate from the quarantine area and other residents, preferably in a separate building.
Rooms housing small groups of cats (testing negative for FeLV and FIV infections and vaccinated against FPV and upper respiratory tract disease), potentially with an adjacent outdoor area are ideal (Figure 1). Fencing must ensure that interactions with other animals (including birds) are prevented. Cats must have access to fresh water and shade as well as protection from rain and cold weather. To facilitate adoption, potential new owners should be able to view the cats, but windows for viewing should be of perspex or glass, not wire mesh.
Pregnant and lactating queens and their litters should be housed in a separate area. Each queen needs a separate pen, and no other cat should be allowed to share it. Ideally, these cats should not be housed in a shelter but rather in guest families organised and facilitated by the shelter.
The entrance to each section should have facilities for hand washing and places for clean coveralls. Ideally there should be washrooms where the carers can wash hands (Figure 2. Hand and equipment disinfectants should be easily accessible to use. Overshoes should be provided, or a boot bath of disinfectant should be placed at the entrance/exit of the quarantine area and the isolation facilities. Equipment for cleaning, disinfecting feeding etc. must be available for each area and must be kept strictly there. To facilitate identification, different colours for food and water bowls, litter trays, beds etc. per area should be used.
Corridors should have non-porous surfaces with easily disinfectable, rounded corners. Floors of the indoor facilities and furniture should be easily cleanable (e.g. no carpets allowed).
Each room for cat accommodation must include a sufficient number of litter trays: one tray for each adult cat plus one extra). Litter trays should be placed away from food and water bowls. Also sufficient food and water bowls, beds, scratching posts, toys and hiding areas should be provided.
The use of cages should be restricted to special circumstances, like medical indications (e.g. during quarantine period, after surgery or injuries, in the isolation facilities); regional legislation about the adequate size of cages must be considered.
In all accommodations, attention must be paid to provide a suitable environmental temperature (10-29 °C), good air quality (10-12 exchanges per hour), prevention of noise and other stressful (Hurley, 2005; Geret et al., 2011).
During evolution, cats have assumed a solitary lifestyle. Animal density in rescue shelters should therefore be kept as low as possible, as the prevalence of pathogenic micro-organisms and consequently infectious disease is correlated with population density and size. In ideal shelters, cats are housed individually or only together with cats from the same original household.
Groups should be kept stable, as far as this is achievable with the turnover / adoption of cats by new owners. Kittens should be kept in a special quarantine facility together with only their litter mates, and without contact to adults other than their queens. High animal density does not only increase the risk of infectious diseases, but may also produce stressful situations. No formula for the recommended number of cats per group can be given, as additional elements like environmental enrichment and the quality of care may have a great influence.
With respect to the management of infectious diseases, groups should be kept as small as possible. Coronavirus infections for example occur at significantly higher rates in multicat situations as compared to single cat households. In catteries and shelters with more than 6 cats, this infection is virtually always present (Pedersen, 2009). ABCD recommends to keep groups of ≤3 cats per room (Addie et al., 2009), otherwise the risk of cross infection increases dramatically.
Various pathogens affecting felines are ubiquitous and frequently introduced into shelters. In a rescue shelter in Belgium, Zicola et al. (2009) found prevalence rates for feline herpesvirus and feline calicivirus of 20.1 and 33.1 %, respectively . In the UK, FCV prevalence is approximately 30 % (Radford et al., 2001; Coyne et al., 2007). The pathogens may be shed intermittently or continuously over prolonged periods of time (also subclinically). In the shelter environment rapid and efficient spread may occur already during the first week after introduction of incoming cats (Pedersen et al., 2004).
Careful observation and examination of the health status of cats in a shelter, especially of new arrivals, and testing procedures are essential in order to detect infectious (and other) diseases at an early stage.
Care workers should be instructed about the risk of zoonotic infection (especially rabies; in endemic areas stray cats should always be approached with caution).
Each incoming cat should receive a full health check by a veterinary surgeon (eyes, ears, nose, mouth, teeth, lymph nodes, heart, lungs, abdomen, limbs, claws, tail, skin, temperature, general condition). 'Clipnosis' (Pozza et al., 2008) may aid in the examination of difficult cats.
Cats should be specifically checked for gastrointestinal, respiratory, and dermatological problems, as these are commonly contagious and should be diagnosed and treated immediately.
Incoming cats older than 4 weeks should be dewormed and treated for external parasites. In areas endemic for heart worm, cats should be tested for this infection and be placed on a prevention regime.
Every cat in a shelter should be neutered.
Details of all medical interventions should be recorded and stored.
Arrival in a shelter is always stressful; stress should be minimised to avoid exacerbation (e.g. of latent coronavirus infection leading to FIP) or reactivation (e.g. of a latent FHV-1 infection) of infections.
Cats should not be euthanised, unless in a moribund, terminal condition. If appropriate treatment is unavailable and cats are suffering, euthanasia should be considered for humane reasons. ABCD does not recommend the euthanasia of healthy FIV or FeLV infected cats, unless they cannot be kept separate from the rest of the population.
Standard of care for cats after having passed quarantine
Active efforts should be made to improve the chances of re-homing shelter cats as quickly as possible. Gouveia et al. (2011) showed that lengthy periods spent in a shelter eventually may be associated with decreased activity levels, decreased food uptake and a greater tendency towards antagonistic behaviour. Additionally a shorter turnover time contributes to a reduction of circulating pathogens (Hurley, 2005).
Cats that are not re-homed should receive regular health checks at intervals recommended by their veterinarian. Special attention should be paid to signs of stress, frustration or behavioural changes.
Regular deworming and flea treatment (as well as heart worm prevention in endemic areas) should be performed.
Booster vaccinations should be performed, and a complete record of the medical history should be kept.
Considerations of euthanasia have been mentioned; a long-term stay in a shelter may have implications on the quality of life. The establishment of an Ethics Committee can be helpful.
The decision to test all incoming cats for FeLV antigen and FIV antibodies rests with the individual shelter, but it is essential during the quarantine period in shelters where contact between cats cannot be prevented. Especially in areas with high retrovirus prevalence, cats that are negative at first testing should be retested six weeks later and in the meanwhile kept in quarantine. This time period is necessary to reduce the risk of missing a recently infected cat, since it may take up to six weeks (or even longer) after FIV infection for antibodies to become detectable (Sellon and Hartmann, 2006), and 4 to 6 weeks to become positive for FeLV antigen (Hartmann, 2006). If a cat tests positive for any retrovirus, it should be housed separately until adoption.
A positive FeLV antigen test may indicate a transient infection, but as this is rarely detected by FeLV antigen tests, and cats may remain provirus-positive, retesting is not mandatory in shelter situations, and such cats should be considered infected. However, false-positive results may occur, and retesting should be performed, especially in areas with low FeLV prevalence. Healthy cats with either retrovirus infection should be adopted out as soon as possible, but only to indoor-only, single-cat households. Prospective owners have to be informed about the existing infection and the consequences (potential recurrent illness, shortened life expectancy, responsibility to avoid virus spread to other cats).
Kittens up to 6 months of age might still test positive for FIV due to maternally derived antibodies and may not be infected (Levy et al., 2003). Therefore, kittens should be kept in quarantine or rehomed and retested at 6 months of age.
Both retroviral infections may persist for long periods of time without clinical signs. FeLV is shed in large amounts, especially via the saliva, and may be efficiently transmitted. Testing minimises the risk of FeLV introduction into the shelter. While friendly social interactions suffice for FeLV transmission, FIV is spread mainly by biting. Especially in socially unstable groups under shelter conditions, the risk of FIV transmission is therefore high. FeLV- or FIV-positive cats should not be housed together with retrovirus-negative cats. FIV infected cats can be housed together, and FeLV infected cats can be housed together, but they should not be mixed. Their immunocompromised status must be considered: they are particularly susceptible to infections, and their health status must be monitored. It should be kept in mind that some secondary infections have a zoonotic potential.
Testing for other infectious agents
The ABCD does not recommend testing incoming cats for other infectious agents, including FCoV, FCV, FHV, FPV, lung worms, unless there are specific clinical signs. We also do not recommend testing for intestinal parasites but rather deworming all incoming cats.
After clinical examination, each healthy cat aged 6 weeks or older (with rare exceptions, e.g. if unambiguous documentation of vaccination is provided) should be immediately vaccinated against FPV, FHV and FCV infections. In the face of an outbreak, vaccination starting at 4 weeks may be considered. Modified live vaccines (MLV) for parvovirus should be used because of their rapid onset of immunity (Greene and Addie, 2006). For FCV, inactivated and MLV products are available; because of the high turnover rates in shelters, MLV are preferred, as protection develops more quickly. However, in immunocompromised cats, FIV- or FeLV-positive cats, in cats with chronic disease (if vaccination is indicated at all) as well as in cats with chronic stomatitis and FCV infection MLV should be avoided.
If FPV, FHV-1 and FCV outbreaks occur in a shelter, passive immunisation can be performed using immunoglobulin products, where available.
The vaccination course should be continued (if the cat has not been re-homed in the meantime) at 3-4 weekly intervals until the age of 16 weeks. When disease is seen in this time period, more frequent vaccination (every 2 weeks) should be considered. For cats older than 16 weeks, a single dose of a FPV MLV and two doses of FHV and FCV vaccine, 2-4 weeks apart should be administered.
Adult cats with a complete vaccination history (including the vaccination one year after the kitten vaccination course) should be boostered annually against FHV-1 (Thiry et al., 2009), FCV (Radford et al., 2009) and against FPV at intervals of three years, unless special conditions indicate otherwise (Truyen et al., 2009).
Cats should not be rehomed earlier than 48 hours after vaccination in order for any side effect to be detected before joining the new owner.
For sick or pregnant cats, the decision has to be taken individually, but vaccination is recommended whenever justifiable, and as soon as possible. Pregnant cats should never receive a live FPV vaccine. Passive immunisation with FPV antiserum (or anti-CPV-2 canine globulin) may be considered.
New owners should be informed about the pet's vaccination history and when the next booster will be due. A vaccination certificate should be provided.
Hygiene is the most important aspect of infectious disease prevention. The measures should ensure that contact between shedders of infectious agents and susceptible animals is avoided, if possible. New infectious agents and diseases are emerging continuously and are impossible to predict. Maintaining high levels of hygiene, and having them enforced by a well-trained staff will prevent such diseases from spreading and becoming catastrophic. Lack of hygienic measures may have disastrous consequences; to give an example: outbreaks of virulent feline calicivirus in veterinary surgeries resulted in their closure for days to weeks.
It is essential to continuously train and coach the staff, to re-evaluate the vaccination strategy and to enforce the practice routines with infectious disease. As an example, the resistance of infectious agents in the environment must be considered. Parvovirus, and oocysts of Isospora for example, can survive in the environment for months to years. Indirect transmission is a major risk in any environment with a high turnover of animals. Thus Clay et al. (2006) have shown that FCV can survive for 3 days on telephone buttons and receivers, and 1-2 days on computer mice. – Careful planning needs to go into how to decontaminate these objects, as well as disinfecting hands, the consulting room table and the routine cleaning between consultations in the veterinary surgery.
The spread of infections and disease may be controlled by separate accommodations and quarantine, movement control, hygiene procedures of care workers, barrier nursing, disinfection, vaccination, and reduction of animal density, as detailed below. In addition, chronic or recurrent stress should be minimised to keep animals (and people) healthy.
Movement control has to be considered between the areas described above, in order to prevent the spread of infectious agents to susceptible animals through direct contact or indirectly, via persons or equipment.
During the quarantine period cats should not be moved to the accommodations for healthy, FeLV and FIV negative cats. Cats showing signs of infectious disease, like upper respiratory tract disease, or testing positive for FeLV or/and FIV should be transferred to isolation facilities.
In the quarantine and isolation areas individual pens should be used.
If ever possible interactions between cats should only be possible for healthy cats originating from the same household.
To prevent indirect transmission through persons or fomites, protocols are required that detail the hygiene procedures to be followed by care-workers.
Care workers should not wear street clothes in the facility. Professional clothing should be easily cleanable or disposable (including shoe covers, gloves etc.). In the quarantine and isolation areas, protective clothing (overalls, aprons, gloves, footwear or boots) should always be used and changed (preferably disposable) or at least disinfected between cats. Clothing should never be taken outside the respective area. If overshoes are not used, footbaths should be available. However, poorly maintained footbaths may contribute to the distribution of pathogens - they need to be cleaned and changed at least twice daily. Disposable footwear is always a preferable option.
For the healthy cat accommodation, care workers may use the same apron / overall for one unit.
Each area should be equipped with its own set of food and water bowls, litter trays, bedding, cleaning equipment, rubber gloves, footbaths, overshoes etc. It is helpful to have these in different colors to avoid confusion.
Access to quarantine and isolation areas should be restricted rigorously. Ideally, different persons should take care of different groups of cats. Otherwise barrier nursing processes should be strictly followed.
A disinfectant hand wash should be used between handling individual cats, before and after breaks, and by all visitors.
All cages and pens should be cleaned daily. Cleaning of one cage / pen / area should be completed before moving to the next one. A deep clean and disinfection should be performed when a cat is homed before the cage / pen is used for the next animal.
A routine should be established whereby susceptible 'clean' animals should be fed first, and their litter trays changed first. Older, vaccinated animals should be attended to next, followed by the cats in quarantine, and finally the sick cats. The person tending the cats should not go back to the susceptible cats after dealing with those who are sick. Each cat should be provided with two sets of litter trays and bowls, so that while one is being cleaned and disinfected, the cat may use the other. Larger shelters will have separate attendants for healthy kittens, adult cats and sick cats. The most hygienic shelters will provide an overall, overshoes, boots or a foot bath and rubber gloves for staff to wear when attending each individual pen.
Pens and cages should be thoroughly cleaned with detergent to remove organic matter before disinfection. For disinfection (especially between cats inhabiting pens), an appropriate disinfectant should be used. As in shelters non-enveloped viruses such as parvo- and calicivirus are of particular concern, only disinfectants that are efficacy-tested against these viruses should be used.
Common disinfectants known to inactivate non-enveloped viruses are, among others, based on aldehyds, peracetic acid, monopersulfate (potassium peroxymonosulfate), or hypochlorite. As alcohols do not inactivate parvoviruses they should not be used as a sole measure. It is important to observe the correct dilution and recommended contact time. Where coccidial infections can occur, premises should be regularly steam cleaned, and disinfectants specifically tested against coccidians should be used in addition to the regular disinfectants. Pens should be left empty for as long as possible between occupants.
If foot baths are used at the entrance to or exit of the quarantine area and isolation facilities, they should be cleaned and the disinfectant changed at least twice daily.
On a daily basis, food and water bowls as well as litter trays must be cleaned thoroughly. Whenever needed they should be soaked in disinfectant for the recommended time, rinsed carefully, dried and returned to the same cat(s). Litter trays and dishes must not be cleaned at the same time in the same sink. In pens with runs and cages for healthy cats, “spot cleaning” may be considered, as long as the housing is used by the same cat (Figure 3). “Spot cleaning” means that cleaning measures are performed while the cat remains in the cage instead of moving it. Non-tracking cat litter is preferable, in order to reduce spreading of e.g. parvo- and coronaviruses.
Bedding and soft materials are either disposed of or cleaned from organic material, soaked in disinfectant and then washed in a washing machine at as high a temperature as possible. Furniture, toys and scratch-posts should be removed or cleaned and disinfected if possible.
Information about transmission and shedding of viruses is provided in Table 1, of other infectious diseases in Table 2.
Infection Survival outside host Virus shedding Mode of transmission Prevention of infection
FCV up to 1 month (Radford et al., 2009) continuous direct contact (sneezed droplets) and indirect transmission vaccination; excellent hygiene; sneeze barriers
FHV 12 – 18 hours intermittent, lasts 7-14 days direct contact, sneezed droplets Vaccination reduces the risk of clinical signs, but not infection; stress reduction essential
FeLV minutes continuous direct contact essential -especially via saliva, faeces; transplacental, milk rare Test all cats before mixing them, vaccination may be considered
FIV minutes continuous * direct contact essential – mainly biting; transplacental rare Test all cats before mixing them
FCoV/FIP up to 7 weeks (Scott, 1998) can be intermittent mainly via faecal-oral route; indirect, through cat litter; shared litter trays, poop scoops; not transplacental excellent hygiene, especially faeces
Parvovirus up to 1 year usually only 24-48 hours, but can be up to 6 weeks faecal-oral route, indirect, transplacental Vaccination is highly recommended for all cats; excellent hygiene and disinfection
Rabies minutes continuous for a few days (just before and during period of clinical signs) biting Vaccination is very effective.
* virus load is very low
during the long asymptomatic phase
Infection Survival outside host Shedding Mode of transmission Prevention of infection Chlamydophila felis only a few days at room temperature (Greene and Sykes, 2006) in ocular secretions, usually for about 2 months, but can be much longer mainly direct since organism is fragile; but indirect (e.g. on hands) is possible since elementary body can survive outside host Vaccination may be considered. B.bronchiseptica up to 24 weeks in water and moist environment in oropharyngeal and nasal secretions, up to 19 weeks mainly direct and indirect from coughed aerosol Interspecies transmission between cats and dogs is possible. Vaccination may be considered. Toxoplasma gondii years in rodents or other intermediate host; oocysts highly resistant in the environment 2 weeks in cats’ faeces cats are usually infected by ingestion of oocyst-contaminated food and water not really an issue in most multicat environments and probably not feasible anyway Protozoa (Giardia, Isospora, Tritrichomonas) Oocysts survive months to years in environment in faeces ingestion usually regular steam cleaning of environment; check water and food if suspected sources of infection
Stress reduction is important for overall health especially in a shelter environment. It serves e.g. to lower the risk for development of feline peritonitis from a latent coronavirus infection (Rohrer et al., 1993), or to avoid reactivation of latent feline herpesvirus.
Stress results from various unpleasant stimuli, such as noise, odour, uncomfortable temperature, unfamiliar people, animals and environments, as well as unskilled handling. Even minor changes, such as moving from one cage to another or being placed in a carrier, can be stressful for cats. Stressful events are amplified when unpredictable, or when the animal lacks the opportunity to modulate their effects through behavioural responses (Carlstead et al., 1993; Hurley, 2005). A feline stress-scoring system has been proposed (Beata et al., 2007), which may help to monitor the success of interventions.
In animal shelters, cats housed at high densities or in large groups display more signs of stress than singly-housed cats. If they had not been socialised to other cats, they also experience more housing stress. Stable groups are the best option, because arrival and departure of new animals inevitably creates stress, apart from the disease control challenge (Hurley, 2005). When keeping cats in groups, attention should be paid to social compatibility.
High-sided cardboard boxes or easily disinfectable beds allow timid cats to cover from view (Rochlitz, 1999; Ellis, 2009). In facilities where both dogs and cats are sheltered, cats should be housed separately (not only to avoid contact, but also to reduce stress from barking).
Offering possibilities for hiding, playing and watching outside activities is important for stress reduction and general well-being. However, efforts at environmental enrichment must take a cat’s individuality into account. What is relaxing to one cat may be stressful to another, depending on past experience, genetics, and individual temperament (Hurley, 2005).
Pheromones are chemical messagers that trigger a social response in members of the same species. It has been claimed that their application to a cat's living space may provide environmental enrichment (Pageat and Gaultier, 2003). Westropp and Buffington (2004) reported positive experiences with a synthetic analogue of the naturally occurring feline facial pheromone. However, in a systematic review of the scientific literature, Frank et al. (2010) found insufficient evidence for effectiveness of pheromones for the treatment of undesirable behaviour in cats and dogs.
When considering to build a rescue shelter, it makes sense to consult an authority like International Cat Care (formerly the Feline Advisory Bureau) or the UC Davis Koret Shelter Medicine Program. Advice on e.g. sneeze barriers, pen construction and dimensions to minimise disease spread can be obtained from dedicated specialists. It is also helpful to visit a number of rescue shelters and animal hospitals to see what is available and what the options are.
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