Please enable JavaScript.

Coggle requires JavaScript to display documents.

Toxoplasmosis in the domestic cat: Risk factors, prevention and…

- - - - UK provides advice regarding dietary and environmental health risks, but does not screen pregnant women for toxoplasmosis (Nash et al., 2005).
        
        Flatt and Shetty (2013) argue that the UK's current policy of education to reduce risk factors is an effective alternative to preventing congenital toxoplasmosis (#9018e7) REDUCING COSTS
      - Prenatal screening
        
        Higher-prevalence countries, such as France and Austria conduct screening (Hill and Dubey, 2015).
        
        Carried out on a monthly or three-monthly basis to detect seroconversion. IgG or IgM positive women are tested further (Gilbert and Peckham, 2002; Lange et al., 2016).
  - - - Tissue cysts not detectable in meat inspection due to the size of the cysts (Limon et al., 2016).
    - - Heating meat to a temperature of 66C REF
      - Avoidance of infected meat estimated to bring about between 30% and 63% reduction in infection risk for pregnant individuals (Cook et al., 2000).
    - - Dietary customs. # #
        
        Ethiopia has a custom of eating raw beef, therefore tissue cysts are attributed to its high seroprevalance
        
        Raw liver believed to be nutritionally valuable in Korea (Tenter et al., 2000).
      - Type of residence i.e. mud houses are of higher infection risk than brick or concrete houses (Nazir et al., (2017).
      - Urbanisation and movement of individuals from rural ro urban areas can alter the distribution of potential intermediate hosts throughloss of habitat (Yan et al., 2016). Influences numbers of
      - Skinning of fur animals also implicated (Tenter et al., 2000).
    - - Thorough washing of fruits and vegetables before consumption (Tenter, 2009). #
  - - - :check:80% of pregnant women in Northern Europe (UK, Norway, Sweden) are susceptible to toxoplasmosis (Gilbert and Peckham, 2002). However, a low seroprevalence in the UK (9.1%) has been documented (Flatt and Shetty, 2013).
      - :check:Over 95% of children born with congenital toxoplasmosis are developmentally normal, with only a small proportion (2%) becoming neurologically impaired (Gilbert and Peckham, 2002).
      - :!:Doubts as to the reliability of prenatal testing, timing of infection not always pinpointed and if women have acquired the infection prior to conception, they are not at risk of foetal infection (Gilbert and Peckham, 2002).
      - False positive test results
        
        :!:False positive results can also lead to ethical issues such as unnecessary termination of pregnancies (Flatt and Shetty, 2013) and high start up costs (Gilbert and Peckham, 2002) .
        
        :!:Duplicate testing of the same samples would reduce this, but labour intensiveness and cost factors would question the feasibility of this on a wider scale (Flatt and Shetty, 2013)
    - - :!:As few as one tissue cyst is present per 100g of meat, therefore difficult to pinpoint infection (Dubey, 2010).
      - :!:Cultural differences may be hard to change i.e. dietary customs
      - :check: Single market weight animal can yield a large number of individual servings , therefore adequate processing of meat can avoid a large number of potential human infections (Hill et al., 2010).
      - Meat decontamination:
        :!:High cost i.e. gamma-irradiation
        May also increase labour intensiveness at slaughterhouses and alter consumer perception (Opsteegh et al., 2014) and render it feasible only in industrialised countries (Tenter et al., 2000).
    - - :check:Most modern water treatmant systems are effective at eradicating oocysts, (Krueger et al., 2014).
      - :!: Dumètre et al. (2013) note that chlorine-based chemicals for water treatment may not be sufficient to eradicate oocysts.
      - :!: Treated water is often not available to parts of the developing world (Singh, 2016).
- - - - Neutering
        
        :check: population of unwanted cats in rescue centres and strays which could potentially transmit disease. therefore vets should educate owners on responsible pet ownership (Dabritz and Conrad, 2010.)
      - Effective hygiene Effective hygiene measures
        
        Removal of cat faeces
        
        Daily changing of litter (Hartmann et al, 2013; Opsteegh et al., 2015).
        
        Direct contact with cat faeces should not result in infection, as oocysts shed are unsporulated and not infective (Tenter et al., 2000), as a 24 hour period is required for sporulation (Brescianiet al., 2013)
        
        Pregnant women
        
        Case control study by Cook et al. (2000) did not find cat contact to be a risk factor, but based on interview only of pregnant women.
        
        Correct PPE i.e. gloves if someone else cannot empty litter box (CDC, 2016).
        
        Disposal of cat faeces in normal household waste in a sealed plastic bag(Hartmannet al., 2013)
        
        Removal of faeces regularly from areas where children, especially, could come into contact with oocysts, for example the garden (Stull et al., 2013).
        
        Regular brushing/bathing of other pets in the household (Tenter et al., 2000).
        
        Dogs can carry oocysts on their fur from rolling in cat faeces or soil contaminated with oocysts (Tenter et al., 2000; Oi et al., 2015).
        
        Oocysts do not sporulate on the fur of dogs or cats (Hartmann et al., 2013).
        
        Cleaning of areas contaminated by cat faeces i.e. litter boxes with hot water heated to at least 70C and an appropriate detergent (Tenter et al., 2000).
        
        COST-BENEFIT ANALYSIS OF HYGIENE PRECAUTIONS
        :check: Limited testing for environmental contamination, therefore effective hygiene and faeces disposal from owners is a way of controlling environmental spread REF
        :check:Less risk of domestic cats tracking sporulated oocysts from the litter tray indoors/outdoors (Dubey et al., 2015).
        :check: Subsequent effective heat treatment when dispose of cat faeces in landfill, less contamination of water/soil (Opsteegh et al., 2015)
        :!: Possible difficulty for owners locating and collecting cat faeces if defecating outdoors or away from the property (Nutter et al., 2004).
        :!: Changing attitudes of the public to adopt more strict hygiene measures (REF)
      - Cat feeding regimes
        
        Feeding commercial dried/tinned food rather than raw diet (Elmore et al., 2010; Hartmann et al., 2013).
        
        COST-BENEFIT ANALYSIS OF FEEDING A COMMERCIAL DIET
        :!: Changing attitudes of owners to reduce feeding raw diets i.e. some may believe it is a more "natural" diet (Freeman et al., 2013).
        :check: A raw diet is a prominent risk factor for development of T. gondii infections in cats.
        Finnish study showed a seroprevalence of 54% in cats fed raw meat from a sample of 490. (Jokelainen et al., 2012).
        :check: Avoids the potential public health risk of feeding a raw diet to cats REF
        
        If a raw diet is fed, freezing meat at a temperature below -12C should be sufficient to kill oocysts whilst avoiding reduction in meat quality (Hartmann et al., 2013).
    - - Prey i.e. rodents and birds, form natural component of feline diet (Freeman et al., 2013), .
      - Equip cat with a bell to reduce hunting whilst still allowing outdoor access (Opsteegh et al., 2012).
      - COST-BENEFIT OF KEEPING CAT INDOORS:
        Psychological wellbeing of animals compromised if not allowed outside, impacts ability to express normal behaviour
  - - - :!:A vaccine for T gondii is currently not available, but it would be difficult, in a practical sense, to vaccinate all stray cats. The cost of setting up a national programme for the capture and vaccination of stray cats must be considered (Opsteegh et al., 2015).
      - :!:Difficult to quantify the number of stray cats in a geographical area, as such cats can fluctuate between being 'stray' and 'owned' as new owners adopt and feed them (Dabritz and Conrad, 2010).
        
        A study by Nutter et al. (2004) showed that 55% of cats presented by owners were former strays, with 13% and 8% having been obtained from a neighbour or a shelter, respectively,
      - :check:Major source of infection, particuarly in urban areas as a result of hunting habits being increased as oposed to domestic cats fed on commercial food (Dorny et al.,2002).
      - Population control of feral cats
        
        :!:Animal rights groups may object to certain methods of population control i.e. euthanasia of stray cats, on a moral level (Opsteegh et al., 2015).
        
        :check:Feral cats are a major reservoir of T.gondii, significantly higher seroprevalence than in domestic (pet) cats (Nutter *et al., 2004;
  - - - COST -BENEFIT OF VACCINATION:
        :check: Toxoplasma vaccine costs £3 per ewe and provides lifelong immunity, equating to 50/60p per pregnancy. Abortion can cost around £85 per ewe (NADIS, note dated).
  - - - Daily cleaning of catteries with appropriate cleaning products, ensuring all faecal matter is removed will minimise the ability of oocysts to sporulate and become infective.
      - T. gondii oocysts are resistant to chlorine and other types of disinfectants due to its resilience to chemical degradation (Dumètre et al., 2013). But can be inactivated by ammonia, formalin and iodine (CFSPH, 2005).
      - COST-BENEFIT ANALYSIS OF GOOD BIOSECURITY MEASURES
        :!: Potential harm to cats or owners where disinfectants are used at high concentrations in order to kill oocysts (Dubey et al., 2014).
        :check: Staff/owner education on the correct ratios of disinfection will help effectively kill oocysts in the environment REF.
    - - Correct storage of feed to minimise risk of contamination by roaming cats (Hartmannet al., 2013; Torrey and Yolken, 2013; Schlüter et al., 2014)
      - Ensure any aborted material from sheep is disposed of promptly and in a suitable manner (Wright, 2016).
        Biocontainment of ewes which have aborted or have given birth to stillborn or weak lambs.
        Fostered ewe lambs should not be retained for breding (NADIS, Not dated)
      - Correct disposal of animal carcasses, as may be a source of infection for intermediate hosts and cats (Opsteegh et al., 2016) .
      - Buying in replacement stock from areas of low T. gondii seropositivity (Opsteegh et al., (2016). Check vaccination history and health status of all new stock (NADIS, not dated).
      - Housing:
        Slatted floors allow easier cleaning and less chance of contamination (Opsteegh et al., 2016).
      - Rodent/cat control
        
        Alternatives to cats to control rodents on farms i.e. traps, baits and poisons
        
        Control the number of cats present on a farm: Minimise the potential for feed and water contamination (Hartmannet al., 2013; Torrey and Yolken, 2013; Schlüter et al., 2014).
        
        Wallander et al (2016) argue that this may not be the best option due to the role what water contamination in soil can play in dispersing infection to wide areas, therefore the problem may not be with farm cats specifically.
      - Use of separate overalls/boots when entering a potentially T.gondii infected areas (Hill et al., 2010).
  - - - Quarantine: Ideally for 3 weeks minimum to allow shedding of any oocysts and for antibodies to develop. Separate quarantine for kittens, as at higher risk of increased seroprevalence (Frymus et al., 2013).
        Give new arrivals a hiding box in order to minimise stress during quarantine (Mostl et al., 2015). Stress may increase cortisol levels, leading to an increased risk of contracting infectious diseases (Vinke et al., 2014).
      - Isolation: Limitation of this with T. gondii as difficult to know when to isolate due to the asymptomatic nature of the infection.
      - Normal housing area: Must have sufficient fencing to prevent contact with other animals i.e. rodents, birds . Perspex or glass preferable to wire mesh (Frymus et al., 2013).
  - - - Vaccine development ongoing, which aims to prevent oocyst shedding (Elmore et al., 2010).
      - COST-BENEFIT OF POTENTIAL VACCINATION OF CATS:
        :!: Vaccine currently being developed is live and therefore there is a potential of infection for humans handling the vaccine (Verma and Khanna, 2013).
        :check: Would stop cat shedding oocysts by inhibiting complete development of oocysts (Verma and Khanna, 2013).
        :!: Owner compliance may be an issue in order to widely implement any potential vaccine (REF)
        # #
  - - - Education
        
        Neutering
        
        :check: population of unwanted cats in rescue centres and strays which could potentially transmit disease. therefore vets should educate owners on responsible pet ownership (Dabritz and Conrad, 2010.)
        
        Effective hygiene Effective hygiene measures
        
        Removal of cat faeces
        
        Daily changing of litter (Hartmann et al, 2013; Opsteegh et al., 2015).
        
        Direct contact with cat faeces should not result in infection, as oocysts shed are unsporulated and not infective (Tenter et al., 2000), as a 24 hour period is required for sporulation (Brescianiet al., 2013)
        
        Pregnant women
        
        Case control study by Cook et al. (2000) did not find cat contact to be a risk factor, but based on interview only of pregnant women.
        
        Correct PPE i.e. gloves if someone else cannot empty litter box (CDC, 2016).
        
        Disposal of cat faeces in normal household waste in a sealed plastic bag(Hartmannet al., 2013)
        
        Removal of faeces regularly from areas where children, especially, could come into contact with oocysts, for example the garden (Stull et al., 2013).
        
        Regular brushing/bathing of other pets in the household (Tenter et al., 2000).
        
        Dogs can carry oocysts on their fur from rolling in cat faeces or soil contaminated with oocysts (Tenter et al., 2000; Oi et al., 2015).
        
        Oocysts do not sporulate on the fur of dogs or cats (Hartmann et al., 2013).
        
        Cleaning of areas contaminated by cat faeces i.e. litter boxes with hot water heated to at least 70C and an appropriate detergent (Tenter et al., 2000).
        
        COST-BENEFIT ANALYSIS OF HYGIENE PRECAUTIONS
        :check: Limited testing for environmental contamination, therefore effective hygiene and faeces disposal from owners is a way of controlling environmental spread REF
        :check:Less risk of domestic cats tracking sporulated oocysts from the litter tray indoors/outdoors (Dubey et al., 2015).
        :check: Subsequent effective heat treatment when dispose of cat faeces in landfill, less contamination of water/soil (Opsteegh et al., 2015)
        :!: Possible difficulty for owners locating and collecting cat faeces if defecating outdoors or away from the property (Nutter et al., 2004).
        :!: Changing attitudes of the public to adopt more strict hygiene measures (REF)
        
        Cat feeding regimes
        
        Feeding commercial dried/tinned food rather than raw diet (Elmore et al., 2010; Hartmann et al., 2013).
        
        COST-BENEFIT ANALYSIS OF FEEDING A COMMERCIAL DIET
        :!: Changing attitudes of owners to reduce feeding raw diets i.e. some may believe it is a more "natural" diet (Freeman et al., 2013).
        :check: A raw diet is a prominent risk factor for development of T. gondii infections in cats.
        Finnish study showed a seroprevalence of 54% in cats fed raw meat from a sample of 490. (Jokelainen et al., 2012).
        :check: Avoids the potential public health risk of feeding a raw diet to cats REF
        
        If a raw diet is fed, freezing meat at a temperature below -12C should be sufficient to kill oocysts whilst avoiding reduction in meat quality (Hartmann et al., 2013).
      - Prevent cat from hunting by keeping domestic cats indoors:
        Prevents contact with potentially infected rodents (Tenter et al., 2000). Impacts welfare of cat
        
        Prey i.e. rodents and birds, form natural component of feline diet (Freeman et al., 2013), .
        
        Equip cat with a bell to reduce hunting whilst still allowing outdoor access (Opsteegh et al., 2012).
        
        COST-BENEFIT OF KEEPING CAT INDOORS:
        Psychological wellbeing of animals compromised if not allowed outside, impacts ability to express normal behaviour
    - - TNR schemes (Gerhold and Jessop, 2013). LINKS TO
      - Minimise feeding of stray cats to discourage them from entering residential areas and schools, as they may serve as reservoirs of infection for humans (Nutter et al., 2004).
      - COST BENEFIT ANALYSIS OF STRAY/FERAL CAT CONTROL
        
        :!:A vaccine for T gondii is currently not available, but it would be difficult, in a practical sense, to vaccinate all stray cats. The cost of setting up a national programme for the capture and vaccination of stray cats must be considered (Opsteegh et al., 2015).
        
        :!:Difficult to quantify the number of stray cats in a geographical area, as such cats can fluctuate between being 'stray' and 'owned' as new owners adopt and feed them (Dabritz and Conrad, 2010).
        
        A study by Nutter et al. (2004) showed that 55% of cats presented by owners were former strays, with 13% and 8% having been obtained from a neighbour or a shelter, respectively,
        
        :check:Major source of infection, particuarly in urban areas as a result of hunting habits being increased as oposed to domestic cats fed on commercial food (Dorny et al.,2002).
        
        Population control of feral cats
        
        :!:Animal rights groups may object to certain methods of population control i.e. euthanasia of stray cats, on a moral level (Opsteegh et al., 2015).
        
        :check:Feral cats are a major reservoir of T.gondii, significantly higher seroprevalence than in domestic (pet) cats (Nutter *et al., 2004;
    - - Keeping meat producing animal indoors throughout their lifetime (Tenter, 2009). WELFARE IMPACT
      - Heat all feed to be administered to 70C (Kijlstra and Jongert, 2008).
      - Vaccination:
        Sheep can be vaccinated against toxoplasmosis (Buxton et al., 2007).
        
        COST -BENEFIT OF VACCINATION:
        :check: Toxoplasma vaccine costs £3 per ewe and provides lifelong immunity, equating to 50/60p per pregnancy. Abortion can cost around £85 per ewe (NADIS, note dated).
      - COST-BENEFIT ANALYSIS OF FARM CONTROL
        :!: Consumer demands for improved animal welfare may question the feasibility of keeping animals indoors permanently (Van der Giessen et al., 2007; Meerburg and Kijlstra, 2009; Hill et al., 2010).
        :!:Heat-treating food is uneconomical and often facilities are insufficient to do so.
        :!:May not have capacity to keep all animals indoors for their lifetime. Ethical issue also posed.
        :check: In intensive production systems, pigs fed on concentrate food and housed on concrete bedding, whereas organically farmed pigs kept on straw bedding and are more likely to contact infected rodents (Van der Giessen et al., 2007).
        :check:Greater attention to detail can be given to cleaning if animals not continuously housed, therefore may be protective in the case of i.e. pig farms where an all-in-all-out system is used (Opsteegh et al., (2016).
        :check:Easy to implement on-farm cat control measures as part of the current biosecurity protocol, wider benefits for food safety and the reduction in infection of animals reared more extensively (Opsteegh et al., 2015).
        :check:Rodent control alternatives shown to decrease T.gondii seropositivity by 63% (Hill et al., 2010).
    - - Disinfection
        
        Daily cleaning of catteries with appropriate cleaning products, ensuring all faecal matter is removed will minimise the ability of oocysts to sporulate and become infective.
        
        T. gondii oocysts are resistant to chlorine and other types of disinfectants due to its resilience to chemical degradation (Dumètre et al., 2013). But can be inactivated by ammonia, formalin and iodine (CFSPH, 2005).
        
        COST-BENEFIT ANALYSIS OF GOOD BIOSECURITY MEASURES
        :!: Potential harm to cats or owners where disinfectants are used at high concentrations in order to kill oocysts (Dubey et al., 2014).
        :check: Staff/owner education on the correct ratios of disinfection will help effectively kill oocysts in the environment REF.
      - Farm
        
        Correct storage of feed to minimise risk of contamination by roaming cats (Hartmannet al., 2013; Torrey and Yolken, 2013; Schlüter et al., 2014)
        
        Ensure any aborted material from sheep is disposed of promptly and in a suitable manner (Wright, 2016).
        Biocontainment of ewes which have aborted or have given birth to stillborn or weak lambs.
        Fostered ewe lambs should not be retained for breding (NADIS, Not dated)
        
        Correct disposal of animal carcasses, as may be a source of infection for intermediate hosts and cats (Opsteegh et al., 2016) .
        
        Buying in replacement stock from areas of low T. gondii seropositivity (Opsteegh et al., (2016). Check vaccination history and health status of all new stock (NADIS, not dated).
        
        Housing:
        Slatted floors allow easier cleaning and less chance of contamination (Opsteegh et al., 2016).
        
        Rodent/cat control
        
        Alternatives to cats to control rodents on farms i.e. traps, baits and poisons
        
        Control the number of cats present on a farm: Minimise the potential for feed and water contamination (Hartmannet al., 2013; Torrey and Yolken, 2013; Schlüter et al., 2014).
        
        Wallander et al (2016) argue that this may not be the best option due to the role what water contamination in soil can play in dispersing infection to wide areas, therefore the problem may not be with farm cats specifically.
        
        Use of separate overalls/boots when entering a potentially T.gondii infected areas (Hill et al., 2010).
    - - Use of synthetic pheromones to help manage stress among cats and reduce the occurrence of shedding (Mostl et al., 2015).
      - Compartmentalisation of units LINKS TO
        
        Quarantine: Ideally for 3 weeks minimum to allow shedding of any oocysts and for antibodies to develop. Separate quarantine for kittens, as at higher risk of increased seroprevalence (Frymus et al., 2013).
        Give new arrivals a hiding box in order to minimise stress during quarantine (Mostl et al., 2015). Stress may increase cortisol levels, leading to an increased risk of contracting infectious diseases (Vinke et al., 2014).
        
        Isolation: Limitation of this with T. gondii as difficult to know when to isolate due to the asymptomatic nature of the infection.
        
        Normal housing area: Must have sufficient fencing to prevent contact with other animals i.e. rodents, birds . Perspex or glass preferable to wire mesh (Frymus et al., 2013).
      - Antibody testing of cats entering the shelter/cattery Economic inviability in some cases
      - COST-BENEFIT ANALYSIS
        :!:Shelters often do not have the money to implement ideal measures for disease prevention
        :!: New buildings may be required for isolation and quarantine to ensure COST OF NEW BUILDINGS/FACILITIES
    - - Vaccination of cats
        
        Vaccine development ongoing, which aims to prevent oocyst shedding (Elmore et al., 2010).
        
        COST-BENEFIT OF POTENTIAL VACCINATION OF CATS:
        :!: Vaccine currently being developed is live and therefore there is a potential of infection for humans handling the vaccine (Verma and Khanna, 2013).
        :check: Would stop cat shedding oocysts by inhibiting complete development of oocysts (Verma and Khanna, 2013).
        :!: Owner compliance may be an issue in order to widely implement any potential vaccine (REF)
        # #