epidemiology of rabies in skunks in texas

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Epidemiology of rabies in skunks in Texas Tom J. Sidwa, D.V.M. Zoonosis Control Branch Texas Department of State Health Services

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Epidemiology of rabies in skunks in Texas. Tom J. Sidwa, D.V.M. Zoonosis Control Branch Texas Department of State Health Services. Epidemiologic study. Objective To obtain epidemiologic information on rabies in skunks in Texas Sample Population - PowerPoint PPT Presentation

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Page 1: Epidemiology of rabies in skunks in Texas

Epidemiology of rabies in skunks in Texas

Tom J. Sidwa, D.V.M.Zoonosis Control Branch

Texas Department of State Health Services

Page 2: Epidemiology of rabies in skunks in Texas

Objective To obtain epidemiologic information on

rabies in skunks in Texas Sample Population

Reports of skunks submitted for rabies testing in Texas from 1953 through 2007

Epidemiologic study

Page 3: Epidemiology of rabies in skunks in Texas
Page 4: Epidemiology of rabies in skunks in Texas

Animal Rabies Cases in Texas

Annually >90% of all cases are in wildlife species

skunks and bats usually most affected species skunks most commonly affected

species during 14 of the 20 years from 1988 through 2007

Page 5: Epidemiology of rabies in skunks in Texas

Data Extracted From Reports seasonality of rabies in skunks seasonality of human and domestic animal

exposures to rabid skunks commonly reported clinical signs of rabies in

skunks animals frequently exposed to rabid skunks common routes of exposure of domestic animals to

rabid skunks disposition of domestic animals exposed to rabid

skunks age and gender of humans exposed to rabid skunks usual routes of exposure of humans to rabid skunks

Page 6: Epidemiology of rabies in skunks in Texas

Materials and Methods Testing largely due to exposure of humans or

domestic animals Testing done at one of 5 laboratories in State

direct immunofluorescence microscopic examination of brain tissue impressions

Variant typing performed at DSHS Lab monoclonal antibodies against the viral nucleoprotein to identify

rabies virus variants Nucleoprotein sequencing

Rabies case investigations performed by personnel from

DSHS Regional Zoonosis Control local health departments local rabies control authorities.

Page 7: Epidemiology of rabies in skunks in Texas

Materials and Methods The type and amount of data available for

each year of the study varied earliest years of the study

Data on numbers of rabid skunks were available only from historical copies of yearly summaries of statewide rabies cases

type and amount of information collected during case investigations tended to increase over the years

information on domestic animals and humans exposed to rabid skunks was not entered in the database in full-year increments until 1987

information on rabies virus variants was available only during the later years of the study

Page 8: Epidemiology of rabies in skunks in Texas

RESULTS

Page 9: Epidemiology of rabies in skunks in Texas

Annual variationsnumbers of rabid skunks 1953-2007

0

100

200

300

400

500

600

700

800

900

1953 1955 1957 1959 1961 1963 1965 1967 1969 1971 1973 1975 1977 1979 1981 1983 1985 1987 1989 1991 1993 1995 1997 1999 2001 2003 2005 2007

Year

No

. of

rab

id s

ku

nk

s

Page 10: Epidemiology of rabies in skunks in Texas

Annual variationsnumbers of rabid skunks 1985 - 2007

0

200

400

600

800

1000

1200

1400

1600

1800

2000

1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007

Year

No

. of

Sku

nks

Positive Skunks

Total Skunk Submissions

Page 11: Epidemiology of rabies in skunks in Texas

Distribution of rabid skunks Urban vs. Rural

0

500

1,000

1,500

2,000

2,500

3,000

1985 -1989

1990 -1994

1995 -1999

2000 -2004

2005 -2007

Year

No

. o

f ra

bid

sk

un

ks

White = UrbanBlack = Rural

Page 12: Epidemiology of rabies in skunks in Texas

Monthly variation

numbers of rabid skunks

0

200

400

600

800

1,000

1,200

1,400

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

Month

No

. o

f ra

bid

sku

nks

Page 13: Epidemiology of rabies in skunks in Texas

Striped SkunkMephitis mephitis

Page 14: Epidemiology of rabies in skunks in Texas

Hooded SkunkMephitis macroura

Page 15: Epidemiology of rabies in skunks in Texas

Hog-Nosed SkunkConepatus leuconotus

Page 16: Epidemiology of rabies in skunks in Texas

Western Spotted Skunk Spilogale gracilis

Page 17: Epidemiology of rabies in skunks in Texas

Eastern Spotted Skunk Spilogale putoris

Page 18: Epidemiology of rabies in skunks in Texas

Species of rabid skunks

From 1985 through 2007 68.56% of confirmed rabies positive

skunks were speciated upon receipt at lab

Of these 99.48% were identified as striped skunks

0.37% were identified as hog-nosed skunks 0.12% were identified as spotted skunks 0.02% was identified as a hooded skunk.

Page 19: Epidemiology of rabies in skunks in Texas

Rabies virus variants

Page 20: Epidemiology of rabies in skunks in Texas

Domestic animal exposure to rabid skunks

0

200

400

600

800

1000

1200

1400

1987 1989 1991 1993 1995 1997 1999 2001 2003 2005 2007

Year

Nu

mb

er

Rabid Skunks

Exposed Humans

Exposed Animals

Page 21: Epidemiology of rabies in skunks in Texas

Human Exposure to rabid skunks

0

200

400

600

800

1000

1200

1400

1987 1989 1991 1993 1995 1997 1999 2001 2003 2005 2007

Year

Nu

mb

er

Rabid Skunks

Exposed Humans

Exposed Animals

Page 22: Epidemiology of rabies in skunks in Texas

Human Exposure to rabid skunks

0

2

4

6

8

10

12

14

16

18

0-5 6-10 11-15 16-20 21-25 26-30 31-35 36-40 41-45 46-50 51-55 56-60 61-65 66-70 71-75 76-80 >80

Age range (y)

No

. o

f in

div

idu

als

Males

Females

Page 23: Epidemiology of rabies in skunks in Texas

Mode of Human Exposure1987 through 2007

Other than bite exposures one of the most common methods - person

with a break in the skin petting or cleaning a dog that had been in a fight with a rabid skunk

Bite exposure – anatomical location in order of frequency Feet arms and hands

trying to separate a dog from a rabid skunk Face

most often a sleeping person

Page 24: Epidemiology of rabies in skunks in Texas

Skunk Behavior Associated with Human Exposures

most commonly reported behaviors attacking dogs appearing outside during the day attacking humans entering a dog pen approaching or entering a house acting sick attacking a cat or other animal entering a tent.

Page 25: Epidemiology of rabies in skunks in Texas

Behavior of Laboratory-Confirmed Rabid Skunks

All 362 rabid skunks - 2007 most frequent behaviors

entering a dog pen (148 incidents) appearing outside during the day (140

incidents) attacking pets (64 incidents)(Multiple behaviors could be exhibited by a single rabid

skunk)

Page 26: Epidemiology of rabies in skunks in Texas

Associated Costs confining and observing exposed domestic

animals Post-exposure prophylaxis in exposed humans

and animals 170 lb. human ~ $2,400 for biologicals alone

costs associated with further preventing disease transmission

Domestic animal vaccination Enhanced stray animal control Population reduction Trap Vaccinate Release Ultimately Oral Rabies Vaccination Program

Page 27: Epidemiology of rabies in skunks in Texas

Study Limitations

Failure to consistently submit suspect skunks for testing

Limited nature of data available during early years of study period

Page 28: Epidemiology of rabies in skunks in Texas

ACKNOWLEDGEMENT

Coauthors: Texas Department of State Health

Services Ernest H. Oertli, DVM, PhD, DACVPM Pamela J. Wilson, MEd Patrick R. Hunt, BS

Texas State University, San Marcos, Texas

Rodney E. Rohde, MS

Page 29: Epidemiology of rabies in skunks in Texas

APPRECIATION Technical Assistance

Dena Garrison Bonny Mayes Jesse Blanton Robert Dowler Jerry Dragoo David Schmidly Craig Ramey Keith Clark