NDWC Chennai 2013 - Infectious Disease Control - Paula boyden

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  • Don’t need to have state of the art facilities to have good disease control. Much of it depends on what we do with them that matters Equally quite often small changes can make a big difference
  • Direct In an ideal world all new animals would be quarantined; realistically won’t work due to the volumes taken in i.e. shaking hands / sniffing bottoms
  • i.e. anything a dog or cat comes into contact with Air: Kennel cough in dogs – infectious aerosol. Can sneeze around 3ft, so need at least 4ft distance between kennels across central walkway People behaviour very important in biosecurity: Staff trained Correct procedures
  • Ideally stop infection getting into shelters. Realistically aiming to minimise the risk of infection Minimise effects of infection i.e. spread within a shelter Incubation e.g. spread of infection at school/one of audience with sore throat. Go thro a period before clin sx Have to accept some admission to shelter will be incubating disease – no clinical signs, therefore cannot detect Excretion Towards end of the incubation period animals will start to shed. Excretion will be millions of organisms per gram of vomit or d+ before think it has an infection i.e. cannot say an individual is healthy, can only say it is clinically well Carriers e.g. Kennel cough, most only shed for few weeks, but can be up to a year for some individuals i.e. Need to be aware of the DISEASES we are dealing with
  • Zoonosis: Disease that can be transmitted from animals to humans All food poisoning organisms: Salmonella, Campylobacter 40% dogs carry Campylobacter, biggest cause of food poisoning in the UK and commonest human zoonosis in Europe. Main source poultry
  • Remove all faeces: organic material and disinfectant = nice smelling shit Clean thoroughly: smooth, impervious surfaces. Will dilute infectious material Pressure hose: useful BUT too often and will destroy material i.e. don’t do every day but as part of routine. NB: Coat oils on floor/walls – if poorly cleaned will remain in situ. Start to look soiled with grease/fat so pressure wash monthly. Disinfect: Need to mix with water to work properly. Follow correct dilution. Look at defra.gov.uk for approved disinfectants. Do not make stronger – not necessarily better. Equally weaker will be ineffective. May find 2 dilution levels – everyday use and in face of infection. If have outbreak often good to change disinfectant e.g. Trigene / Virkon. NB: Commercially made disinfectant have detergents to get into nooks and crannies. Hydrogen peroxide and chloride NOT a good substitute. Leave 20-30 mins to allow to work – won’t be effective if remove as soon as apply DRY: Essential part to complete the process. Most organsims hate drying. E.g. use sqeegee. I.e. bateria/virusesd prefer warm and wet
  • Hand washing
  • Ideally wash hands between each animal. Not practical in sanctuary situation, but should at least be done between blocks
  • Quarantine is ideal i.e. keep separate for 2 weeks after entry, but not practical. Would need facility x2 current size Isolation : Any animal showing sx of disease OUT of centre and INTO isolation. i.e. any animal with any symptom. E.g. mild diarrhoe, isolate until know better Progression : of animals through centre. Less likely to be infected. Keep high risk away from low risk. Therefore at DT: Intake block: ensure no infection Re-homing block: Once been through intake Booked block: least likely infected. NB random stray pups/handovers in Dublin Cleaning starts at booked (low infection) and work towards intake (high infection). Therefore, even if limited manpower, can limit risk of disease Sectioning: If can section block e.g. 2-4 kennels then a door / 2-4 kennels then a door Putting in doors a useful way of controlling infection. i.e. stay open most of the time
  • Walls between kennels need to be solid. Free flow of air means that disease particles not only enter central corridor but can spread from dog to dog via this route
  • Consider fans in central corridor pushing air through the kennels and to the outside i.e. cleanest air in central corridor
  • Definition of an antigen: a substance which the immune system recognises as foreign or non self Definition of an antibody: a glycoprotein which has the capacity to recognise and bind to foreign molecules
  • Immunity: The power to resist infection or the action of certain poisons Inherited / innate immunity e.g. horses don’t get foot and mouth, cats don’t get canine distemper, dogs don’t get FeLV NB: Be aware that immunity not immediate i.e. even if vaccinate on entry to sanctuary, may still succumb to disease
  • Feeding: Well fed  better immunity Pregnancy: decreases immunity. Huge draw on body Stress decreases immunity. Take dog off streets into sanctuary, can’t choose what to do so stress levels ^^^ Drugs e.g. steroids NB: Study done a couple of years ago re stress and cortisol levels. Suggested HAC as so high. Smell other dogs but cannot see and cannot get away.
  • Level of immunity needs to be ABOVE the level of infection i.e. need to keep level of infection BELOW level of immunity. Do this by proper management and proper cleaning
  • If are able to/cannot manage, as level of infection increases, exceeds immunity and disease results This will be a process of progression: incubation period  excretion  clinical signs of disease i.e. trying to avoid levels of infection exceeding levels of immunity. Otherwise potential exponential rise of infection Greater the stress, greater the immune system is suppressed and individuals become more prone to infection. Therefore HOW WE MANAGE ANIMALS IN SHELTERS IS CRITICAL
  • Emphasise importance of management and cleanliness. Higher the level of infection, more rapid the onset of disease. What does this mean? Lower levels means greater time lag before infection happens; may be the difference between being able to vaccinate and stimulate immunity. At least should reduce severity of clinical signs if not prevent altogether
  • Live vaccines are non-harmful strains of a disease that have had their ability to cause disease modified (reduced). They create a quicker immune response and immunity lasts longer. Killed vaccines have been rendered inactive. Immunity generally doesn’t last as long and more frequent boosters are required. Some vaccines would not be safe to have live components so killed vaccines have to be used. Heterologous vaccines: Some vaccines use components similar to the disease but not exactly the same to give cross protection against the diseases e.g. cowpox was used to vaccinate against smallpox in humans (smallpox is now officially eradicated from the world). Early distemper vaccines were actually measles vaccines (the 2 diseases come from the same family). Shope Fibroma virus cross protects against Myxomatosis. Toxoids: As mentioned before: tetanus is a bacterial infection. The bacteria produces toxins (poisons). It is these poisons which cause the clinical signs of tetanus. Therefore the vaccine aims to stimulate the immune system to bind to the poisons to prevent the clinical signs of tetanus. Similarly, in the case of acute injury e.g. a cut, tetanus anti-toxin is administered to bind to any poisons before they can cause the clinical signs of tetanus. Specific Antigen: Some vaccines are genetically engineered and have a specific piece of the virus which stimulates immunity e.g. FeLV. i.e. these are a purified form of vaccine – it is only the part of the virus that stimulates the immune system that is used in the vaccine. Live vaccines: small, non harmful dose of the infectious agent. Will replicate in the body (hence the marked response) but will not cause disease. 4 main differences between live and killed vaccines (as listed): Greater stimulation of immune system: more dramatic response Much more rapid response i.e. rapid mobilisation due to replication of vaccine Generally single dose, but young e.g. puppies/kittens special case Immunity generally lasts longer
  • 4 main differences between live and killed vaccines; reiterate as per diagram Greater stimulation of immune system: more dramatic response Much more rapid response i.e. rapid mobilisation due to replication of vaccine Generally single dose, but young e.g. puppies/kittens special case Immunity generally lasts longer
  • Live vaccines are non-harmful strains of a disease that have had their ability to cause disease modified (reduced). They create a quicker immune response and immunity lasts longer. Killed vaccines have been rendered inactive. Immunity generally doesn’t last as long and more frequent boosters are required. Some vaccines would not be safe to have live components so killed vaccines have to be used. Heterologous vaccines: Some vaccines use components similar to the disease but not exactly the same to give cross protection against the diseases e.g. cowpox was used to vaccinate against smallpox in humans (smallpox is now officially eradicated from the world). Early distemper vaccines were actually measles vaccines (the 2 diseases come from the same family). Shope Fibroma virus cross protects against Myxomatosis. Toxoids: As mentioned before: tetanus is a bacterial infection. The bacteria produces toxins (poisons). It is these poisons which cause the clinical signs of tetanus. Therefore the vaccine aims to stimulate the immune system to bind to the poisons to prevent the clinical signs of tetanus. Similarly, in the case of acute injury e.g. a cut, tetanus anti-toxin is administered to bind to any poisons before they can cause the clinical signs of tetanus. Specific Antigen: Some vaccines are genetically engineered and have a specific piece of the virus which stimulates immunity e.g. FeLV. i.e. these are a purified form of vaccine – it is only the part of the virus that stimulates the immune system that is used in the vaccine.
  • NDWC Chennai 2013 - Infectious Disease Control - Paula boyden

    1. 1. Infectious Disease Control Paula Boyden BVetMed MRCVS Veterinary Director Dogs Trust
    2. 2. How is Disease Spread?
    3. 3. Direct Transmission
    4. 4. Indirect Transmission• Floors/walls• Bowls/blankets• Air• People
    5. 5. What are we trying to achieve? (Biosecurity) • Purpose: – Minimise risk of infection – Minimise effects of an infection • Factors Affecting Spread: – Incubation – Excretion of infection – Carriers
    6. 6. Zoonotic Disease
    7. 7. How can we deal with the threat of disease?
    8. 8. Cleaningwww.disinfectants.defra.gov.uk
    9. 9. CLEANING• Remove all faeces• Clean thoroughly• Pressure hose• Disinfect• Leave 20-30 minutes• Dry
    10. 10. PEOPLE• Personal hygiene – Hand washing – Personal gels – clothing
    11. 11. How to Wash Your Hands
    12. 12. MANAGEMENT• Quarantine• Isolation• Progression• Sectioning
    13. 13. AIR MANAGEMENT
    14. 14. AIR MANAGEMENT
    15. 15. Vaccination
    16. 16. Types of Immunity I m m u n ityI n h e r it e d A c q u i r e d N a t u r a l ly A c q u i r e d A r t i f i c i a l ly
    17. 17. Factors Affecting Immunity• Feeding• Pregnancy• Stress• Drugs
    18. 18. INFECTION & IMMUNITYImmunityInfection
    19. 19. Rising Infection and Immunity Symptoms Immunity Infection Excretion starts Infection
    20. 20. High and Low Levels of Infection Infection Symptoms High infection levels Low infectionImmunity levels Excretion starts Time
    21. 21. Types of Vaccine• Live, attenuated e.g. Parvovirus• Killed (inactivated) e.g. Rabies• Heterologous e.g. smallpox• Toxoids e.g. Tetanus Toxoid• Specific Antigen (Sub unit)
    22. 22. Vaccination 10000Antibody Livetitre Killed 1 0 2 4 6 8 10 12 14 16 18 20 22 24 Age (weeks)
    23. 23. Summary• What we do is critical in disease control – Understanding the diseases – Cleaning protocols – Animal/shelter management – Vaccination• Vaccination is not an excuse for poor husbandry
    24. 24. Thank You

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