Rabies

1. Rabies
PREM (2015A5PS862H)
BITS PILANI HYDERABAD CAMPUS

2. Introduction
Rabies is caused by a virus , which infects cell of
nervous system and is excreted later in the saliva
Zoonotic disease ( diseases that are transmitted to
humans by animals).
Any mammal can get rabies (including human)
Cats, cattle, and dogs
bats and foxes

3. Mode of transmission
• Most common modes
rabies virus is found in saliva, transmission to humans or
animals occurs as a result of a bite from a rabid animal
any contact of saliva with mucous membranes(eyes, nose,
mouth) or a wound
• Can also be transmitted by
drinking raw milk from rabies infected animals
organ transplant (human to human)
kidney transfer , cornea

4. Morphology of rabies virus
• Size is 180 nm * 75 nm, bullet shaped , ss RNA virus
• N proteins + RNA = nucleoprotein complex

5. Function of proteins
N protein: tight packaging of RNA, prevent from degradation
L protein: Viral RNA dependent RNA polymerase i.e make new
RNA for new formed virus
P protein: regulate L protein activity
M protein: packaging RNP in to new virus, virus envelope
G protein: bind with receptor of host cell
nicotinic acetylcholine receptor
low affinity NGF receptor

6. Pathogenesis:

7. Dysfunction of brain
1) Rabies virus alters the level of proteins involved in ion
haemostasis ( H+ ATPase and Na+/K+ ATPase
upregulated, Ca+2 ATPase downregulated )
2) Downregulation of proteins involved in docking and fusion
of synaptic vesicles to presynaptic membrane
3) Cell death by either apoptosis or necrosis

9. How rabies goes from bite site to brain ?
• p75NTR receptor, a protein found on the tips of
peripheral neurons( NGF)
• rabies virus behaves very similar to NGF
• It binds to p75NTR where it absorb in to neuron
• Transport independent of p75NTR is also more erratic,
with a larger proportion of viruses moving in the wrong
direction
• rabies virus is transported with p75NTR, it moves at
about 8 cm (a bit more than three inches) per day

10. Symptoms:
The period between the bite and the onset of symptoms is called
the incubation period.
 4 to 12 weeks
 can also range from a few days to six years.
 The initial onset of rabies begins with flu-like symptoms,
including:
fever
muscle weakness
tingling
feel burning at the bite site

11. Contd…
As rabies progresses, there are two different types of the
disease that can develop
 Furious Rabies
- exhibit signs of hyperactivity
excited behaviour
hydrophobia (fear of water)
insomnia
anxiety
confusion
agitation
hallucinations
excess salivation

12. Contd…
 Paralytic Rabies
Infected people slowly become paralyzed, will
eventually slip into a coma, and die.
take longer course than the furious form.
30 percent of rabies cases are paralytic.

14. Thanks

15. Diagnosis
Tests that can be used to confirm a diagnosis of rabies in people who
are experiencing symptoms associated with rabies include:
skin biopsy - A sample of skin is taken (usually from the neck) and
examined under a microscope (skin biopsy) to determine whether the
virus is present. Samples of saliva are also examined to check for the
virus
saliva test – saliva can be tasted by virus isolation or traverse
transcription followed by polymerase chain reaction(RT PCR)
blood tests - your blood is checked for the rabies antibodies
Negri bodies- found in the cytoplasm of certain nerve
cells containing the virus of rabies

16. Treatment
Treatment after exposure can prevent the disease if
administered promptly, generally within 10 days of infection
Includes:
Management of animal bite wound(s)
administration of rabies immunoglobulin and immediate
vaccination

17. Management of animal bite wound(s)
 washing the wound as soon as possible with soap and
water for approximately five minutes is effective in
reducing the number of viral particles
 Povidone-iodine or alcohol is then recommended to
reduce the virus
 leave the wound open - do not try to stitch it because
this could expose your nerve endings to the rabies
virus

18. rabies immunoglobulin and vaccination
• Consist of 1 dose of immunoglobulin (20 IU/kg) and 5 doses of
rabies vaccine over 28 days (days 0,3,7,14 and 28)
• immunoglobulin works by stimulating the production of
antibodies that can stop the virus from spreading.
• If you have never been vaccinated, you should receive five
doses of the vaccine
• if you have previously been vaccinated, you should receive two
doses of the vaccine (start, second one three days later)
• The doses are given by injection into the shoulder muscle