1. Biology and Epidemiology of the Rabies Virus
Rachel Radcliffe, DVM, MPH
CDC Career Epidemiology Field Officer
Division of Infectious Disease Epidemiology

2. Objectives Describe epidemiology of rabies virus
Describe transmission and pathogenesis of rabies virus
Outline management of animals potentially exposed to rabies
Outline management of animals that potentially expose humans to rabies

3. The Rabies Virus Lyssavirus of the Rhabdoviridae family
Bullet-shaped, RNA virus
Infects only mammals
Various strains of rabies virus exist

4. Rabies Epidemiology — World
>55,000 deaths worldwide
Mainly Africa and Asia
60–70% of human cases are children 5–15 years of age
~98% of human cases caused by dog bites

5. Rabies Epidemiology — United States
Human rabies deaths relatively rare
4 deaths in 2009
>90% of animal rabies cases occur in wildlife
6,690 animal rabies cases in 2009
92% wildlife animals
8% domestic animals
Rabies annual prevention costs ~$300 million

6. Map of terrestrial rabies reservoirs in the United States during 2009
Map of terrestrial rabies reservoirs in the United States during Raccoon rabies virus variant is present in the eastern United States, Skunk rabies in the Central United States and California, Fox rabies in Texas, Arizona, and Alaska, and Mongoose rabies in Puerto Rico.

7. Rabies Epidemiology — West Virginia
Most animal rabies cases occur in wildlife
Cat most common domestic animal to be rabies-positive
Raccoon-strain rabies endemic to eastern portion of state
Bat strain found throughout state
Most cases occur during warm-weather months

8. Counties with Confirmed Cases of Raccoon Strain Rabies In West Virginia, 2001–2010
HANCOCK
BROOKE
OHIO
MARSHALL
WETZEL
TYLER
PLEASANTS
WOOD
JACK-
SON
RITCHIE
WIRT
ROANE
CAL-
HOUN
MONONGALIA
MARION
TAYLOR 2
DODD-
RIDGE
LEWIS
GILMER
PRESTON
BARBOUR
TUCKER
UP-
SHUR
RANDOLPH
HARRISON
MORGAN
BERKELEY
JEFFERSON
MINERAL
HAMPSHIRE
GRANT
HARDY
PENDLETON
BRAXTON
WEBSTER
POCAHONTAS
NICHOLAS
GREENBRIER
FAYETTE
CLAY
PUTNAM
KANAWHA
BOONE
MASON
CABELL
WAYNE
LINCOLN
MINGO
LOGAN
McDOWELL
WYOMING
RALEIGH
MERCER
SUM-
MERS
MONROE
Counties with Raccoon-Strain Rabies

13. Rabies Transmission Saliva from bite of infected animal Scratch
Theoretical risk
Saliva or neural tissue contact with mucous membrane (mouth, nose)
Saliva or neural tissue introduced into fresh, open wound*
The top of this slide lists the transmission routes that should be considered exposures. Rabies is spread through saliva or CNS tissue from an infected animal and is most commonly transmitted through bite exposures. Scratches are another potential exposure. Also, if infectious saliva or CNS tissue has contact with mucous membranes or a fresh, open wound this would also be considered an exposure. A fresh, open wound which is a wound that has bled in the past 24 hours.
Other possible but rare transmission routes include aerosol transmission and corneal and organ transplantation from an infected donor.
* Fresh, open wound is defined as wound that has bled in past 24 hours

14. Rabies Pathogenesis
Virus introduced through bite wound, open skin wound, or mucous membrane
Travels along nerves from site of bite to brain
Virus multiplies in brain leading to inflammation
Virus moves from brain to salivary glands and saliva where virus is shed

15. Rabies Pathogenesis
Virus introduced through bite wound, open skin wound, or mucous membrane
Travels along nerves from site of bite to brain
Virus multiplies in brain leading to inflammation
Virus moves from brain to salivary glands and saliva where virus is shed

16. Rabies Incubation Period
Time between bite and appearance of symptoms
Weeks to months
No risk of rabies transmission from infected animal during incubation period
Used to establish confinement periods for animals exposed to potentially rabid animals

17. Rabies Diagnosis Animal diagnosis Post-mortem testing
Direct Fluorescent Antibody (DFA) test
Antigen of virus in brain tissue
Human diagnosis
Several tests required for ante-mortem diagnosis
Saliva, serum, cerebrospinal fluid, hair follicle from nape of neck

18. Rabies Treatment and Prevention in Humans
No effective treatment once clinical signs appear
Rabies post-exposure prophylaxis (PEP) given before onset of symptoms is nearly 100% effective
Rabies PEP
Wound cleansing
Rabies Immunoglobulin (RIG)
Rabies Vaccination
No time limit to give PEP

19. Rabies PEP — Wound Cleansing
Should occur as quickly as possible after wound received
Soap and water or povidone-iodine

20. Rabies PEP — RIG Given only once with first vaccine dose
If not given with first vaccine dose, can be given up to 7 days after first vaccine dose received
If person has previously received PEP or pre-exposure prophylaxis, RIG should not be given

21. Rabies PEP — Vaccination
Previously unvaccinated persons get 4 doses
Days 0, 3, 7, and 14
5th dose dropped from vaccine schedule last year
Intramuscular injections
Previously vaccinated persons get 2 doses
Days 0 and 3
No RIG given

22. Rabies Pre-exposure Prophylaxis
Recommended for certain high-risk groups
Veterinarians, wildlife biologists, animal control personnel
3 vaccine doses
Days 0, 7, and 21 or 28
Does not eliminate need for medical care after an exposure

23. Rabies Treatment and Prevention in Animals
No treatment for animal rabies
No post-exposure prophylaxis for animals
Routine vaccination is the only way to prevent animal rabies
Vaccination schedule for dogs and cats
First vaccine at 3 months of age
Booster vaccine 1 year later
Vaccinate every 3 years after this

24. Management of Animals Potentially Exposed to Rabies
Vaccinated cats, dogs, ferrets
Rabies booster immediately
45 day observation
Under owner’s control
Any sign of illness should be reported and animal evaluated by a veterinarian

25. Management of Animals Potentially Exposed to Rabies
Unvaccinated dogs, cats, ferrets
Euthanasia
Strict isolation for 6 months
Confinement in an enclosure that precludes direct contact with people or other animals
Rabies vaccine upon entry or 1 month prior to release
Any sign of illness should be reported and animal evaluated by a veterinarian

26. Management of Animals Potentially Exposed to Rabies
Expired vaccinations in dogs, cats, ferrets
Evaluated on a case-by-case basis
Information to consider
Severity of exposure
Time lapsed between vaccinations
Number of previous vaccinations
Current health status
Rabies epidemiology

27. Management of Animals Potentially Exposed to Rabies
Vaccinated livestock
Rabies booster vaccine immediately
45 day observation
Multiple rabid animals in a single herd is unusual
Restriction of entire herd usually not necessary
Coordinate with WV Dept. of Agriculture

28. Management of Animals Potentially Exposed to Rabies
Unvaccinated livestock
Euthanasia
Confined under close observation for 6 months
Any signs of illness should be reported and animal euthanized and tested for rabies
Vaccination during confinement can be done
Coordinate with WV Dept. of Agriculture

29. Management of Animals Potentially Exposed to Rabies
Other animals
Consider on case by case basis
Euthanasia generally recommended

30. Management of Animals that Potentially Expose Humans
Dogs, Cats, Ferrets
Owned animals should be observed for 10 days
Rabies vaccination not recommended during this time
Strays should be euthanized and tested
10 day quarantine can be done if resources allow
If not available for testing, PEP should be considered based on rabies epidemiology of area, bite circumstances, etc.

31. Management of Animals that Potentially Expose Humans
Exotic mammalian pets
No established rabies observation period for animals except dogs, cats, ferrets
Consider on case-by-case basis
Information to consider
Type of animal
Rabies epidemiology of area
Bite circumstances

32. Management of Animals that Potentially Expose Humans
Livestock
Not high risk for transmitting rabies
Healthy and available animals can be observed for 14 days
Unknown shedding period of rabies virus in saliva
Euthanasia and testing is other option
Coordinate with WV Dept of Agriculture

33. Management of Animals that Potentially Expose Humans
Wildlife
If available, euthanize and test immediately
If unavailable, PEP should be considered based on
Type of animal
Rabies epidemiology of area
Bite circumstances

34. Management of Animals that Potentially Expose Humans
Small mammals are considered low risk for rabies
Not been found to cause human rabies in US
PEP not usually recommended for these exposures unless animal was sick and rabies activity is high in the area
Groundhogs/woodchucks may pose greater risk
Special consideration for bats

35. Rabies Resources www.cdc.gov/rabies ACIP recommendations
Compendium of Animal Rabies Prevention and Control, 2008
WV Rabies Surveillance, Management, and Control Manual (DC-4)

36. Rabies Summary Human rabies rare in US and WV
Most rabies cases occur in wildlife in US and WV
Transmission occurs through introduction of infectious saliva or neural tissue into the body
Human prevention based on rabies PEP
Animal prevention based on rabies vaccination

37. Animal Management Summary
Management of animals potentially exposed to rabies depends on vaccination status and type of animal exposed
Management of animals that expose humans to rabies depends on type of animal, ownership status of animal, and other factors