RABIES

1. Rabies and Public Health
History
Epidemiology
Pathogenesis
Response

2. 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

3. 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

7. Epidemiology

8. Epidemiology

9. Cases of Animal Rabies,
Virginia, 1999-2003
0
50
100
150
200
250
300
350
400
1999 2000 2001 2002 2003
raccoons
skunk
fox
cat
bat

10. Rabies distribution

11. 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

12. Pathogenesis
 Virus enters the body
 Virus enters NM junctions
 Travels via peripheral nerves to spinal
cord
 Then to brain stem and forebrain

13. 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

14. 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

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

16. Laboratories
 Fairfax County HD
 Norfolk HD
 DCLS Southwest Micro lab.
 DCLS Central lab.

17. 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.

18. Significant exposure
 Bite
 Saliva contact with mucus membrane or
skin break

19. 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.

20. Principles of DFA
Fluorochrome-labeled
Antibody to Rabies Virus
Rabies Virus
infected Cell
Labeled Antibody-
Rabies Virus

21. DFA Results
< Positive Brain
Negative Brain >

22. Public Health Response

23. 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

24. Public Health Response
 Human exposed to livestock
 Typically 10-14 days observation
 Possibly testing + Post exposure tx. (PEP)

25. Public Health Response

26. Public Health Response
 Vaccinated dog, cat or ferret exposed
 Proof of current immunization
 Immediate booster
 45 days confinement
 Testing if signs of rabies develop

27. 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

28. 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

29. Public Health Response
 Livestock exposed
 Vaccinated
 Boost and 3 months observation
 Unvaccinated
 Immediate slaughter or
 6 months observation

30. Public Health Response
 Wildlife exposures
 No observation time
 High risk species
 Low risk species
 Test when possible or situation warrants

31. 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

32. Public Health Response
 Control/Education
 Prompt attention to bites
 Good communication with all parties involved
in follow up
 Prompt PEP when necessary

33. 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

34. Rabies Fun Facts
 Early treatments for rabies in people
included:
 Total immersion in salt water
 Lighting gunpowder in wounds
 Blood letting

35. 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

36. Interesting situations
 Concerning non-bite exposures
 Bat
 Raccoon
 Goat
 Concerning low risk exposures
 Monkey

37. Post Exposure Potpourri
 Peruvian PEP
 Old PEP
 PEP reactions

38. Good Resources
 www.vdh.virginia.gov
 VDH Programs
 Epidemiology Program
 Zoonotic and Environmental Epi.

39. Good Resources
 www.cdc.gov/healthypets
 www.cdc.gov/ncidod/dvrd/rabies
 www.nasphv.org

40. Questions?