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