rabies and public health
DESCRIPTION
Rabies and Public Health. History Epidemiology Pathogenesis Response. 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 1 st century AD. History. First documented case in US Virginia, 1753 - PowerPoint PPT PresentationTRANSCRIPT
Rabies and Public Health
History
Epidemiology
Pathogenesis
Response
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
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
Epidemiology
Epidemiology
Cases of Animal Rabies, Virginia, 1999-2003
0
50
100
150
200
250
300
350
400
1999 2000 2001 2002 2003
raccoonsskunkfoxcatbat
Rabies distribution
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
Pathogenesis
Virus enters the body Virus enters NM junctions Travels via peripheral nerves to spinal
cord Then to brain stem and forebrain
Disease in Animals
Two major clinical types in dogs and cats Furious
Restless, irritable, disoriented, seizuresMore common in cats
ParalyticExtremity paralysis, altered bark, salivatingMore common in dogs
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
Rabies Timeline
incubation
exposure virus shed. signs death
dogs 10 d-6 m 0-5d 0-8d
hu 5d-6y 2-14d
Other ? ? ?
Laboratories
Fairfax County HD Norfolk HD DCLS Southwest Micro lab. DCLS Central lab.
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.
Significant exposure
Bite Saliva contact with mucus membrane or
skin break
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.
Principles of DFA
Fluorochrome-labeled Antibody to Rabies Virus
Rabies Virus infected Cell
Labeled Antibody-Rabies Virus
DFA Results
< Positive Brain
Negative Brain >
Public Health Response
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
Public Health Response
Human exposed to livestock Typically 10-14 days observation Possibly testing + Post exposure tx. (PEP)
Public Health Response
Public Health Response
Vaccinated dog, cat or ferret exposed Proof of current immunization Immediate booster 45 days confinement Testing if signs of rabies develop
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
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
Public Health Response
Livestock exposed Vaccinated
Boost and 3 months observation Unvaccinated
Immediate slaughter or6 months observation
Public Health Response
Wildlife exposures No observation time High risk species Low risk species Test when possible or situation warrants
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
Public Health Response
Control/Education Prompt attention to bites Good communication with all parties involved
in follow up Prompt PEP when necessary
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
Rabies Fun Facts
Early treatments for rabies in people included: Total immersion in salt water Lighting gunpowder in wounds Blood letting
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
Interesting situations
Concerning non-bite exposures Bat Raccoon Goat
Concerning low risk exposures Monkey
Post Exposure Potpourri
Peruvian PEP Old PEP PEP reactions
Good Resources
www.vdh.virginia.gov VDH Programs Epidemiology Program Zoonotic and Environmental Epi.
Good Resources
www.cdc.gov/healthypetswww.cdc.gov/ncidod/dvrd/rabieswww.nasphv.org
Questions?