Rabies and Public Health

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Rabies and Public Health

• History
• Epidemiology
• Pathogenesis
• Response

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History

• A recognized disease as early as 2300 BC
• Aristotle wrote about rabies in 322 BC
• Saliva of rabid dogs was recognized as venomous
  in the 1st century AD

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History

• First documented case in US
• Virginia, 1753
• Colonial times-1950s
• Dogs highest vector risk
• 1960s-today
• Wildlife greatest reservoir

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• Raccoon rabies
• Noticed in FL in mid 50s
• Spread to VA in 1970s
• Seen everywhere but sw VA
• Skunk rabies
• Present in low levels in sw VA since 1960s

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Epidemiology
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Epidemiology
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Cases of Animal Rabies, Virginia, 1999-2003
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Rabies distribution
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Disease Transmission

• Almost always a bite
• Virus cannot enter intact skin
• Virus can cross mucus membranes
• Less efficient
• Breaks in skin are a risk only if wet saliva gets
  in wound

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Pathogenesis

• Virus enters the body
• Virus enters NM junctions
• Travels via peripheral nerves to spinal cord
• Then to brain stem and forebrain

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Disease in Animals

• Two major clinical types in dogs and cats
• Furious
• Restless, irritable, disoriented, seizures
• More common in cats
• Paralytic
• Extremity paralysis, altered bark, salivating
• More common in dogs

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The Disease in Man

• Initial clinical symptoms include anxiety,
  headache, mild fever, irritation at bite site
• Progresses to muscle spasms, difficulty
  swallowing, hydrophobia
• Clinical course is typically short

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Rabies Timeline

• incubation
• exposure virus shed. signs death
• dogs 10 d-6 m 0-5d 0-8d
• hu 5d-6y 2-14d
• Other ? ? ?

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Laboratories

• Fairfax County HD
• Norfolk HD
• DCLS Southwest Micro lab.
• DCLS Central lab.

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Testing

• An animal involved in significant human exposure.
• An animal involved in significant domestic animal
  exposure.
• A bat when significant human exposure can not
  reasonably be determined.

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Significant exposure

• Bite
• Saliva contact with mucus membrane or skin break

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Testing

• Direct Fluorescent Antibody (DFA)
• May be used on fresh or decomposed tissue.
• Produces sensitive and rapid results.
• Considered the most reliable of all available
  technologies.
• Daily quality control steps assure accuracy.

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Principles of DFA
Fluorochrome-labeled Antibody to Rabies Virus
Rabies Virus infected Cell
Labeled Antibody-Rabies Virus
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DFA Results
lt Positive Brain
Negative Brain gt
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Public Health Response
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Public Health Response

• Human exposed to dog, cat or ferret
• Observe animal for 10 days
• Test if illness or death w/in observation period
• Should be discussed with health director
• IS NOT DEPENDENT ON VACCINATION STATUS

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Public Health Response

• Human exposed to livestock
• Typically 10-14 days observation
• Possibly testing Post exposure tx. (PEP)

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Public Health Response
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Public Health Response

• Vaccinated dog, cat or ferret exposed
• Proof of current immunization
• Immediate booster
• 45 days confinement
• Testing if signs of rabies develop

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Public Health Response

• Unvaccinated dog, cat, ferret exposed
• Euthanize or 6 months isolation
• Vaccinate one month prior to release
• Test if signs of rabies develop

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Public Health Response

• Expired vaccination
• Euthanize or 6 month isolation
• Vaccinate immediately and one month prior to
  release
• Depending on the circumstances, some of these
  animals can be considered as currently vaccinated

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Public Health Response

• Livestock exposed
• Vaccinated
• Boost and 3 months observation
• Unvaccinated
• Immediate slaughter or
• 6 months observation

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Public Health Response

• Wildlife exposures
• No observation time
• High risk species
• Low risk species
• Test when possible or situation warrants

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Public Health Response

• Control/Education
• Vaccinate dogs and cats
• Wildlife vaccination initiatives
• Animal control
• Avoid direct contact with wildlife
• Pre-exp. vaccination for high risk professions

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Public Health Response

• Control/Education
• Prompt attention to bites
• Good communication with all parties involved in
  follow up
• Prompt PEP when necessary

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Recent cases in Virginia

• 1998-unknown exposure, silver haired bat variant,
  prison in work program
• 2003-raccoon variant, no history of exposure,
  diagnosed 3 months after death

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Rabies Fun Facts

• Early treatments for rabies in people included
• Total immersion in salt water
• Lighting gunpowder in wounds
• Blood letting

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Rabies Fun Facts

• Famous bite victims
• Emily Bronte
• Cardinal Crescence, 1532
• Rabies was eradicated from the Scandinavian
  countries as early as 1832
• Some MDs used to advise that if a dog drank after
  biting, the dog could not be rabid

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Interesting situations

• Concerning non-bite exposures
• Bat
• Raccoon
• Goat
• Concerning low risk exposures
• Monkey

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Post Exposure Potpourri

• Peruvian PEP
• Old PEP
• PEP reactions

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Good Resources

• www.vdh.virginia.gov
• VDH Programs
• Epidemiology Program
• Zoonotic and Environmental Epi.

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Good Resources

• www.cdc.gov/healthypets
• www.cdc.gov/ncidod/dvrd/rabies
• www.nasphv.org

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Questions?