Unit 3 - Rabies Virus Flashcards
What is the history of Rabies?
- One of the oldest known diseases
Earliest record of rabies from Babylon (23rd century BC)
Homer likens Hector to a “raging dog” in The Illiad (800-700 BC)
- Rabies derived from the Sanskrit word rabhas (“to do violence”) and the Latin word rabere (“to rave”)
Rabid animals often appear angry or in a rage
- Italian scholar Girolamo Fracastoro was the first to describe the true nature of rabies disease (1546)
350 years before Pasteur and Roux developed the rabies vaccine
Describe rabies in the 19th Century
- Rabies was termed hydrophobia (fear of water)
- Canine or street rabies was everywhere, especially Europe.
- The fear of rabies was almost irrational, due to the significant number of vectors and lack of any efficacious treatment
- “Mad” dog symbolized the human fear of rabies for centuries
- Suspected victims often killed themselves or were killed (shot, poisoned, suffocated) or condemned to die
- France passed law in 1810 making it illegal to murder individuals suffering from rabies, hydrophobia or any disease causing fits, convulsions, or madness
Describe the history of rabies when the vaccine was discovered.
- Louis Pasteur and Emile Roux, pioneers of rabies vaccine
Dried strips of spinal cords removed from rabid animals
Pasteur’s first vaccine tested on dogs (50/50 survived)
1886: first human subject injected with Pasteur’s vaccine; 9-yr old boy
- Pasteur’s success made him a hero
Pasteur Institute founded in 1887 to treat rabies victims
Institute widely respected for its research in microbial diseases
What is rabies in animals?
Disease in mammals:
- primarily wildlife (wild dogs, raccoons, skunks, bats, etc.)
- Less frequent in domesticated animals (cats, dogs, livestock)
What are the worldwide important Animal Rabies Reservoirs?
- Asia, Africa, South America, Mexico: wild dogs (threatening over 3 billion people)
- Europe, Canada, Alaska, former Soviet Union: foxes
- Siberia, Japan, Northern India, Europe: raccoon dogs
- Thailand: wild dogs (95% of cases)
- Caribbean Islands: mongooses
- Mexico and South America: vampire bats
What are the U.S. Rabies Management Programs?
- Vaccination programs to control rabies in animals bean in the U.S. during the 1940s and 1950s.
- Wildlife Services Program, part of the USDA distributes vaccines via hand distribution and plane distribution
- Over 10 million oral rabies vaccine baits distributed in the U.S. and Canada in 2003
What are the Oral Rabies Vaccine for wildlife?
- Raboral V-RG vaccine by Merial, Inc.
- In use in the US since 1990
- Recombinant vaccine
Attenuated vaccinia virus
Gene encoding rabies glycoprotein G
What is Human Rabies?
- 15 million post-exposure vaccinations
most common in children aged under 15
90% of human cases in the US were associated with bat bites.
- 55,000 rabies - related human deaths yearly:
dogs source of 99% human rabies death
What is involved between rabies and organ transplantation?
- Infections by corneal transplant have been reported in Thailand, India, Iran, the US, and France.
- June 2004: three organ recipients in US died from rabies transmitted in the transplanted kidneys and liver
- Donor died of brain hemorrhage/unidentified brain disorder
- February 2012: Maryland man died of rabies; received a kidney from an infected donor in 2011
How are U.S. soldiers affected by rabies?
- In August 2011 a U.S. soldier stationed at a military base in New York became ill with symptoms compatible with rabies.
- three months following active deployment in Afghanistan
- variant associated with Afghani dogs
- Soldiers returning from active duty abroad may have unreported animal exposures
What is World Rabies Day?
- Occurs each year on September 28, the anniversary of the death of Louis Pasteur
- Aims to raise awareness about the impact of rabies on humans and animals
promoting government involvement in rabies prevention and control programs
increasing the vaccination coverage of pets and community dogs
improving the educational awareness
What are the clinical signs and symptoms of rabies?
Two forms of Human Rabies
- Furious (encephalitic)
- Paralytic (or dumb)
With either form, incubation period varies
- 4 days to 6 years (rare)
- Average 18-21 days post-exposure
With either form, course of diesase 2-14 days before coma supervenes
- Death occurs on average of 18 days after onset of symptoms
What are the symptoms of rabies during the prodromal period?
(the time of onset specific symptoms)
Heachache
Malaise
Fever
Anorexia
Nausea
Vomiting
What are teh secondary symptoms of Furious Rabies?
- Hydrophobia (fear of water)
- Difficulty swallowing
- Agitation
- Anxiety
- Hallucinations
- Hypersalvation
- Bizarre behavior
- Biting
- Jerky and violent contractions of the diaphragm
What are the Secondary symptoms of Paralytic rabies?
- Lack of hydrophobia
- Lack of hyperactivity
- Lack of seizures
- weakness and ascending paralysis
- These symptoms also apply to animals:
- Animals that are predators show signs of furiuos rabies.
- Nonpredators display paralytic or dumb rabies symptoms
What is U.S. rabies testing in animals?
- Gold Standard is direct fluorescent antibody test (dFA)
Post-mortem test
done on animals behaving abnormally or show consistent rabies signs if human or other animal exposure have occured
- Rabies is present in nervous tissue
Brain is the ideal test tissue: 2 or 3 samples tested
- Brain stem (medulla)
- Cerebellum
- Hippocampus
What is Direct Fluorescent Antibody Test (dFA)?
- Ideal tissue to test for rabies antigen is brain.
- Fluorescently labeled antibodies directed against the viral nucleoprotein.
- dFA test is rapid (30 minutes to 4 hours)
What are the sequential steps of rabies transmission?
