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  Colonial times-1950s Dogs highest vector risk  1960s-today Wildlife greatest reservoir

Historyzzzzzzzzzzzzzzzzzzzzzz zzzzzzzzzzzzzzzzzzzzz  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

Cases of Animal Rabies, Virginia,

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, seizures More common in cats Paralytic Extremity paralysis, altered bark, salivating More 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 exposurevirus shed.signsdeath dogs10 d-6 m0-5d0-8d hu5d-6y2-14d 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

 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 days observation Possibly testing + Post exposure tx. (PEP)

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 or 6 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  VDH Programs Epidemiology Program Zoonotic and Environmental Epi.

Good Resources   

Questions?