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?