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Epidemiology of Rabies
John R. Dunn, DVM, PhD
Communicable and Environmental Diseases
Tennessee Department of Health
Centers for Disease Control and Prevention
Overview
• Rabies virus
• Rabies epidemiology in the US and Tennessee– Skunk rabies– Raccoon rabies and ORV
• Guidance documents– ACIP: Pre-exposure vaccination– Compendium
Rabies virus- Lyssavirus
• Rhabdoviridae- “bullet” shaped RNA virus
• Neurotropic, fatal encephalitis
• Variants- host adapted
Transmission
• Transmission: BITE of a RABID animal
– Virus-laden saliva contacts nerves
• Saliva in fresh cut or abrasion, mucous membranes (scratch?-- no)
• Person to person: theoretical risk, never documented in health care worker
Rabies Epidemiology in the United States
• Human rabies in US: 2 – 5 cases / year– Tennessee case 2002
• PEP: 100% effective– ~ 40,000 treatments/ year
• $2000 – 6,000 / treatment
– ~ 75% unnecessary based on rabies risk
• Animal rabies: 7,000 – 8,000 cases / year (wildlife)– 4 variants: raccoon, skunk, bat, fox– Canine variant no longer enzootic in US
Terrestrial
Wildlife
Rabies
Bat Rabies
Bat-associated Rabies
U.S.- majority of human rabies caused by bats• From 1980-2000, 26/35 (74%) cases • Silver-haired/Eastern pipistrelle bat
Minor wound from bat bite • Difficult to detect • Persons may not recognize exposure
Most human rabies diagnosed post-mortem• Not on differential• Healthcare workers exposed
Rabies Epidemiology in Tennessee
Rabies Testing by the Tennessee Department of Health (TDH)
• Three testing centers– Nashville– Knoxville– Jackson
• Rabies Diagnosis: Direct Fluorescent Antibody testing (DFA) of brain tissue
• Testing performed free of charge
• Not much attention paid to number and characteristics of negative results
Results from 2005
• Review of laboratory slips from 3 testing centers in 2005
• 2017 animal submissions – 2010 submitted to testing centers in TN
• 92 (96%) of 95 counties• 362 different localities• 18 out-of-state
– 7 additional specimens from USDA-WS surveillance program (submitted to CDC)
Most Common Animals Submitted for Rabies Testing to the TDH in 2005
1 0 0
576
695
182023242833
109
184
254
4 0003123160
100
200
300
400
500
600
700
Animal Species
Nu
mb
er
of
Su
bm
issio
ns
TOTAL
POSITIVE
Positive and Negative Submissions for Rabies Testing, TDH, 2005
0
100
200
300
400
500
600
700
Dog Cat Raccoon Bat Skunk
Species
Num
ber
0
2
4
6
8
10
12
14
16
18
20Negative
Positive
Rabies positive animals in Tennessee by year, 1999-2005
0
10
20
30
40
50
60
70
80
90
1999 2000 2001 2002 2003 2004 2005
Year
Nu
mb
er
Skunk
Bat
Raccoon
Dog
Fox
Horse
Other *
*N=4: Cat 2001 (1), 2003 (1); Cow 2002 (1); Opossum 2004 (1)
Unico
i F
– 1
R-1
LakeObion
Dyer
Lauderdale
Tipton
Shelby B - 2 Fayette
Haywood
Crockett
Gibson
Weakley
Carroll
Henry
Madison
Hardeman McNairy
Chester
Henderson
HardinWayne Lawrence
GilesS - 1
Lincoln S - 2
Franklin Marion B - 1
HamiltonB– 2S - 1
Bradley Polk
Perry
LewisF - 1
Dec
atu
r
Hickman
MauryB - 1
Marshall
Bedford S - 2
Moore
CoffeeS-1
Grundy
Seq
uatch
ie
BledsoeRhea
Mei
gs
McMinnMonroe B - 1
Loudon Blount
RoaneSevier
KnoxB – 4F-1
Morgan
ScottCampbell B - 1
Claiborne
Grainger
Union
Hamblen
Jefferson
Cocke S - 2
Stewart
Houston
Humphreys
Montgomery
Dickson
Williamson S - 4
Davidson B - 2
Che
atha
m
Robertson Sumner S - 1
Macon
Trousdale
Wilson S - 1
Rutherford S – 5 H - 1
ClayPickett
JacksonOverton
Fentress
Smith
Dekalb
Canno
n
Warren B -
1V
an
Bur
en
White
Putnam B - 1
Cumberland
Hancock
Hawkins
GreeneS – 1 D - 1
Was
hing
ton
R-1
, S-1
Sullivan
Carter R - 2
Joh
nso
n S
- 1
Benton
TN Rabies Positives (n=48) by County, 2005
Bat - - - - - - - 16 Horse---- 1
Skunk - - - - - 23 Fox - - - - 3
Raccoon - - - -4 Dog - - - - 1
Unico
i C
– 1
LakeObion
Dyer
Lauderdale
Tipton
ShelbyFayette
Haywood
Crockett
Gibson
Weakley
Carroll
Henry
Madison
Hardeman McNairy
Chester
Henderson
HardinWayne Lawrence
Giles
Lincoln S - 1
Franklin Marion
Hamilton
BradleyF-1
Polk
Perry
Lewis
Dec
atu
r
Hickman
Maury
Marshall
Bedford D - 1
MooreS-3
Coffee
Grundy
Seq
uatch
ie
BledsoeRhea
Mei
gs
McMinnMonroe
Loudon Blount
RoaneSevier
Knox
Morgan
ScottCampbell
Claiborne
Grainger
Union
Hamblen
JeffersonS-1
Cocke
Stewart
Houston
Humphreys
Montgomery
Dickson
Williamson S - 4
Davidson S - 2
Che
atha
m
Robertson Sumner Macon
Trousdale
Wilson
Rutherford S – 10
ClayPickett
JacksonOverton
Fentress
Smith
Dekalb
Canno
n
WarrenS-1
Van
B
uren
White
Putnam
Cumberland
Hancock
Hawkins
Greene
Was
hing
ton
Sullivan
Carter
Joh
nso
n
Benton
TN Rabies Positives (n=26) by County, 15 April 2006
Skunk - - 23 Fox - - 1 (Racc Var)
Cat ------- 1 (Racc Var) Dog - 1 (Sk Var)
Skunk, Bat, and Raccoon Rabies in TN, 1999-2005
1 48
4
0102030405060708090
1999 2000 2001 2002 2003 2004 2005
Year
Num
ber
Skunk
Bat
Raccoon
Raccoon variant
Unic
oi
Marion
Hamilton Bradley Polk
Grundy
Sequatchie
Bledsoe
Rhea
Mei
gs
McMinnMonroe
Loudon Blount
RoaneSevier
Knox
Morgan Anderson
Scott
Campbell
Claiborne
GraingerUnion
Hamblen
Jefferson
Cocke
Pickett
Overton
Fentress
Dekalb
Warren
Van
Bure
n
White
Putnam
Cumberland
Hancock
Hawkins
Greene
Was
hing
ton
Sullivan
Carter
John
son
East TN counties with raccoon variant rabies, 2002-Apr 15, 2006
Why is raccoon rabies problematic?
• Raccoons thrive in suburban settings• Aggressive and swift
– Increase in dog and cat (2X) rabies– Increase in other rabid species (foxes,
groundhogs, livestock, etc.)
• Increase in human exposures and need for PEP risk assessment
• Increased animal control calls & anxiety
Tennessee response to raccoon rabies
• Education– Reducing risk– Protecting pets through vaccination
• Increase surveillance– USDA-Wildlife Services (> 20 East TN counties)
• Oral rabies vaccination (ORV) campaign– Appalachian Ridge baiting– GAT baiting
Anticipated ORV Barrier Zone for Raccoon Rabies in the United States
ORV barrier zones forraccoon rabies
2004 cases Proposed ORV
ORV in Tennessee, 2005
GAT
Appalachain Ridge
Guidance documents
http://www.cdc.gov/mmwr/PDF/rr/rr4801.pdf
Imovax® (Sanofi Pasteur)
• Previously used off-label, 0.1ml intradermal for pre-exposure vaccination
• TDH no longer advocating use of Imovax off-label consistent with new ACIP recommendations
• Important for state, regional and local HD to promote rabies vaccination for at-risk persons
http://s94745432.onlinehome.us/RabiesCompendium.pdf
Questions?
John DunnTennessee Department of HealthCommunicable and Environmental Diseases4th Floor, Cordell Hull Building425 5th Avenue NorthNashville, TN 3724615.741.7247