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Public Health Aspects of Rabies Control

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Control of Rabies (see Compendium of Animal Rabies Vaccines ) In domestic animals, rabies control is based upon vaccination, quarantine, ... – PowerPoint PPT presentation

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Title: Public Health Aspects of Rabies Control


1
Public Health Aspects of Rabies Control
  • Lecture 8
  • Dr. Paul Bartlett, MPH., DVM., Ph.D.

2
Source of Rabies Information
  • CDC Web site Very comprehensive!
  • http//www.cdc.gov/ncidod/dvrd/rabies/Professional
    /professi.htm

3
Human Rabies Biologics(Rabies vaccines for
people)
  • Duck embryo vaccine
  • No longer available as of December, 1981
  • Post exposure required 23 SQ injections
  • Local reactions including pain, erythema, and
    induration at the injection site were very common
  • Systemic reactions such as fever, malaise, and
    myalgia occurred in about 33 of recipients.
  • When use as prescribed and used in conjunction
    with HRIG, about 15 of recipients never achieved
    a protective titer.
  • Neuroparalytic reactions were rare.

4
Human Rabies Biologics(Rabies vaccines for
people)
  • Human diploid cell vaccine (HDCV)
  • Rate of allergic reaction usually, limited to
    hives, is approximately 1 in 625
  • Guillaune-Barre-like peripheral neuropathy .3
  • Another report says 30 risk of severe Arthrus
    reaction
  • HDCV is administrated IM due to low rate of
    reaction.

5
Human Rabies Biologics(Rabies vaccines for
people)
  • RabAvert Rabies Vaccine
  • Produced by the Chiron Corporation
  • Purified chick embryo cell vaccine.
  • Licensed in the US in 1997
  • 14 million doses have been used worldwide

6
Immuloglobins
  • Equine antirabies serum (ARS)
  • Still available but not the drug of choice
    because it produces serum sickness in 40 of
    adult recipients.
  • Human rabies globulin (HRIG)
  • Serum from hyperimmunized persons provides
    immediate passive protection against rabies.
  • Adverse reactions rare - drug of choice.
  • In a fresh bite wound, located in a fleshy part
    of the body, all of the HRIG can be injected
    around the wound. If that is not possible then
    the remainder can be injected in the buttocks far
    from the site of the rabies vaccinations. Due to
    the large volume of HRIG involved, injection at
    several sites is recommended.

7
Rational for Rabies ImmunizationPre-exposure
  • Pre-exposure immunization is recommended for
    persons whose vocational or avocational
    activities increase their exposure to animals
    which may be rabid.
  • Veterinarians (RR 312), veterinary technicians,
    animal wardens, hunters and trappers.
  • Pre-exposure immunization protects against
    unknown exposures.
  • Pre-exposure immunization allows for a rapid
    anamnestic rise in rabies titer if followed by
    vaccination or exposure.

8
Rational for Rabies ImmunizationPost-exposure
  • Long incubation period of rabies allows us to
    immunize exposed individuals before the brain is
    affected, but it is most effective when begun
    early after exposure.
  • Use of HRIG provides immediate passive
    immunization for 7 to 10 days, until the vaccine
    can induce active immunity.
  • Local infiltration of HRIG is intended to prevent
    tissue fixation of the virus, but it is only
    effective immediately after a biting incident.

9
Recommended HDCV and HRIG Treatment Schedules -
Pre-exposure
  • Three doses total - on days 0, 7,and 21 or 28.
  • No HRIG is given.
  • Persons wishing to maintain a protective titer
    should have their titer determined and, if their
    titer is low, they should receive a booster dose.
  • Most veterinarians with only infrequent exposure
    do not need to have their boosters or titers
    checked after the primary pre-exposure course.

10
Recommended HDCV and HRIG Treatment Schedules -
Post-exposure
  • 5 doses total - on days 0,3,7,14, 28.
  • HRIG should also be received on day 0.
  • If the person has ever had a protective titer, or
    has ever had the recommended three-dose
    pre-exposure regimen, only two doses of vaccine
    recommended on days 0, 3 and no HRIG is needed.

11
Rational for TreatmentTen-day Observation Period
  • Dogs, cats, and ferrets (as of November 1997)
    which live without clinical signs of rabies for
    10 days following inflicting a bite can be safely
    assumed to have no rabies virus in their saliva
    at the time of the bite.
  • Most states have a law mandating a ten day
    observation period be observed for dogs, cats,
    and ferrets after they bite a human.
  • Under the observation of a vet (in some states)
  • Post-exposure vaccination for humans can be
    delayed when the capture of the correct animal is
    imminent.

12
Rational for TreatmentTen-day Observation Period
  • The ten day observation period is only
    recommended for dogs, cats, and ferrets. All
    other biting animals should be immediately
    euthanized and sent to the laboratory for rabies
    testing. (but there are exceptions)

13
Rational for TreatmentLocal Rabies Prevalence
  • Information regarding the prevalence of rabies in
    your area is available from your local or state
    health department.
  • Some major metropolitan areas of the USA have
    been free from rabies in terrestrial mammals for
    many years.
  • Chicago and New York City are among these.
  • Animal bites occurring in these areas may not
    require post-exposure immunization.
  • This does not include bites inflicted by bats.

14
Rational for TreatmentSpecies of Biting Animal
  • Bites from non-mammals never pose a rabies
    threat.
  • Bites from rodents, lagomorphs, and opossums in
    the USA generally do not necessitate rabies
    prophylaxis.
  • Recently however there have been considerably
    more instances of rodents and rabbits being found
    with rabies.
  • Animals species in different regions of the
    country represent differing degrees of rabies
    exposure potential.
  • Skunks in the Midwest.
  • Raccoons in the southeastern and eastern USA.

15
Rational for TreatmentNature of Bite
  • Deep bites to the head are more likely to
    transmit rabies.
  • Bites to the head are more likely to induce
    rabies and are more likely to result in a shorter
    incubation period.
  • Approximately 15 of bites from known rabid
    animals will result in transmission of rabies if
    the person is not treated (Winkler, CDC).

16
Rational for TreatmentAnimal Tissue Contacted
  • Central nervous system tissue, spinal fluid, and
    saliva are the tissues of major public health
    importance.
  • Other tissues such as muscles, skin, musk (skunk
    spray), and fat have negligible amounts of virus.
  • Contact with blood, urine, or feces does not
    constitute an exposure

17
Disposition of Exposed Animals
  • Each state has different regulations regarding
    handling of animals exposed to rabies (or suspect
    rabid animals).
  • The CDC recommends that exposed dogs, cats, and
    ferrets which are currently vaccinated be
    euthanized, or revaccinated then observed in
    confinement for 45 days.
  • Exposed dogs, cats, and ferrets whose
    vaccination status is not current should be
    euthanized or confined for 6 months with
    vaccination 1 month prior to their release.

18
Animal Bite Trauma
  • Confinement is frequently defined differently in
    various states.
  • Most states specify confinement under the
    supervision of a veterinarian.
  • Regardless of the treat of rabies, animal bites
    in themselves can represent a serious public
    health hazard.
  • 18 to 20 people, usually children, die each year
    from wounds inflicted by dogs. So
  • It should be the responsibly of all veterinarians
    to encourage the euthanasia of vicious dogs from
    the canine population to remove this public
    health hazard.

19
Veterinary Care of Wild Animals
  • Wild animals, most notably skunks and raccoons,
    can create a considerable health hazard when
    people attempt to domesticate them.
  • The exposure potential for rabies for humans is
    greater than for dogs or cats because
  • Wild animals frequently bite and scratch their
    owners.

20
Veterinary Care of Wild Animals
  • The American Veterinary Medical Association, CDC,
    National Association of State and Public Health
    Veterinarians, and the US Animal Health
    Association strongly discourage the vaccination
    or de-scenting of wild animals.
  • Killed rabies vaccine has not been proven
    effective in these animals, and may give the
    owner a false sense of security.
  • De-scenting skunks make them a better pet and
    thereby encouraging ownership.

21
Veterinary Care of Wild Animals
  • In Michigan and most other states, permits must
    be obtained to keep most species of wild animals
    in captivity.
  • In Michigan and other Midwestern states, permits
    are never issued to the general public for owning
    skunks, and rarely issued for raccoons.
  • Veterinarians should not treat wild animals such
    as skunks or raccoons without first making sure
    that the owner has the proper documentation for
    ownership of these animals.

22
Clinical Course
  • Incubation periods vary with virus strain, dosage
    on inoculum and host species.
  • Man - 3 to 66 weeks on average, but maybe up to a
    year
  • Dogs - 3 to 8 weeks average, but maybe up to 6
    months
  • Cats - 9 to 51 days
  • Skunks - 22 to 177 days
  • Foxes - 12 to 153 days
  • Bats - 6 to 145 days
  • Bovines - 20 to 165 days
  • Typical syndrome disposition change, irritably,
    dysphasia, incoordination progressing to either
    the furious or dumb form followed by paralysis,
    coma and death.

23
Control of Rabies (see Compendium of Animal
Rabies Vaccines)
  • In domestic animals, rabies control is based upon
    vaccination, quarantine, stray control and
    education.
  • For several years, there have been more rabid
    cats reported in the US than rabid dogs, yet most
    states do not have cat vaccination laws.
  • Rabies vaccine must be evaluated for safety.
  • MLV are no longer approved by the USDA.

24
Veterinarians Responsibility in Rabies Control
And Finally
  • Actively assist in planning and executing local
    rabies control programs including health
    education.
  • Examine the biting dog or cat initially and take
    the following actions
  • Observe and record any clinical symptoms of the
    animal.
  • Notify the health department of the examination
    results.
  • Advise the owner on the best means of confinement
    and observation.

25
Veterinarians Responsibility in Rabies Control
  • Re-examine the dog, cat, or ferret during the ten
    day observation period
  • Notify the health department as soon as possible
    if a diagnosis of rabies is possible.
  • Confirmation of the diagnosis of rabies is NOT
    needed.
  • If the dog, cat, or ferret exhibits no symptoms
    of rabies at the end of the 10 day observation
    period, report to the health department that the
    animal was not capable of transmitting rabies at
    the time of the bite and recommend that it be
    released from confinement.

26
Veterinarians Responsibility in Rabies Control
  • Remember that in the 10 day observation period
    you are not trying to confirm a diagnosis before
    you call the health department. You are looking
    for any signs which may in any way be compatible
    with rabies.
  • Do NOT wait for an animal to die or exhibit signs
    more definite signs.
  • Do NOT wait until you can confirm some other
    diagnosis.

27
Veterinarians Responsibility in Rabies Control
  • Educate clients on the advantages of dog, cat and
    ferret immunization and dangers of allowing pets
    to run loose.
  • Encouraging rabies immunization is not only
    ethical, but actually the responsibility of the
    veterinarian.
  • Notify the health department of all animal bites
    and suspected rabies cases.
  • Inform clients of the possibility of rabies when
    treating bite wounds on their animals.

28
Veterinarians Responsibility in Rabies Control
  • Remember that the 10 day observation period is
    only possible for dogs, cats, and ferrets.
  • In other species, rabies virus may be shed over a
    more variable period of time.
  • Other species should be sacrificed and sent to
    the laboratory for examination as soon as
    possible.
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