Rabies

Question 1

Rabies Virus

Answer 1

• Rabies Virus genus of the Rhabdoviridae family
• ( - ) ss RNA helical enveloped bullet shaped

Question 2

Rabies Virus Sructure

Answer 2

Question 3

Rabies Replication

Answer 3

Question 4

Rabies Epidemiology

Answer 4

• Rabies exists in two epizoologic forms
• Urban form: Associated with unimmunized dogs and cats
• Sylvatic form: Occurs in wild skunks, foxes, wolves, raccoons, mongooses and bats.
• 55,000 cases per year worldwide with highest in southeast Asia and Indian Subcontinent
• Fewer cases in the United States
• Most of the cases are from wild animals

Question 5

Rabies Pathogenesis

Answer 5

• Introduction of rabies virus through epidermis.
• Replicates in muscles at the site of inoculation
• Enters peripheral nervous system at the neuromuscular junctions
• Spread up the nerves to the CNS
• Replicates exclusively within the gray matter.
• Passes centrifugally along autonomic nerves to reach other tissues, including salivary glands, adrenal medulla, kidney and lungs
• Passage into the salivary glands in animals facilitates further transmission

Question 6

Rabies Incubation

Answer 6

• 10 days to a year
• Depends upon:
• Amount of virus introduced ¥Amount of tissue involved
• Host immune system
• Virus replicates in muscle at the site of bite, asymptomatic

Question 7

Rabies Prodrome (early symptom)

Answer 7

• (2–10 days)
• non–specific symptoms, malaise, headache, fever, nausea, vomiting, upper respiratory distress (sore throat), subtle-mental changes (insomnia), pain, itching, tingling at site of bite

Question 8

Rabies Acute Neurological Phase

Answer 8

• 2-7 days
• “Furious” or “dumb” presentation
• “furious”…. hyperactivity, excitement, disorientation, hallucination, bizarre behavior, hydrophobia, convulsions, aggressive
• “dumb” or paralytic phase…. lethargy, paralysis (respiratory)

Question 9

Rabies goes from acute phase to…

Answer 9

• Coma
• Death (rare exceptions) major cause of deathrespiratory paralysis

Question 10

Rabies Reservoir

Answer 10

• Urban: dogs, cats
• sylvatic: skunks, fox, coyote, wolves, raccoon, bat, mongoose, vampire bat

Question 11

Rabies Diagnosis

Answer 11

Question 12

Rabies Treatment

Answer 12

• Wash wound, instill hyperimmune globulin around wound site
• Immunize with inactivated viral vaccine on days 0, 3, 7, and 14 to induce active immunity
• Immune Globulin (half life-21 days) administered 1- 7 days, not effective after that specifically for pediatric patients

Question 13

Rabies Prevention

Answer 13

•Preexposure prophylaxis:

-Recommended for individuals at high risk of contact with rabies virus, such as veterinarians, spelunkers, laboratory workers and animal handlers

• Vaccine currently used in United States is attenuated rabies virus inactivated with beta propiolactone
• Post exposure prophylaxis: Depends on the condition of exposure