25. RABIES Flashcards

You may prefer our related Brainscape-certified flashcards:
1
Q

What is Rabies?

A

Rapidly progressive, acute infectious diseases of the central nervous system (CNS) in humans and animals

Rabies virus, transmitter through animal vectors

ENCEPHALITIC + PARALYTIC forms —> DEATH

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Etiologic Agent of Rabies

A

Rabies virus is a member of the family Rhabdoviridae
It is specifically a lyssavirus. Most human rabies is transmitted from dogs in countries with endemic canine rabies and dog-to-dog transmission

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Incubation period

A

20 to 90 days

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Pathogenesis

A

Through the wound, the virus infects the nicotonic acetylcholine receptors first at the post synaptic membranes of the NMJ and spreads centripetally along peripheral nerves —> CNS through retrograde axonal transport —> spinal cord/brainstem

Once in the CNS —> rapidly disseminates to other regions via fast axonal transport along neuroanatomic connections

NEURONS ang affected

Once CNS infection is established, CENTRIFUGAL spread along SENSORY and Autonomic Nerves to other tissues including Salivary Glands, Heart, Adrenal Glands and Skin

Acinar glands in salivary glands is where it reciprocates.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Rabies usually present as _____ encephalitis with relative preservation of _______

A

Rabies may be difficult to recognize late in the clinical course when progression to coma has occurred

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

CLINICAL STAGES of RABIES (goes hand in hand with CLINICAL MANIFESTATIONS)

A

Incubation Period
Prodrome
Acute Neurologic Disease (Encephalitic, Paralytic)
Coma Death

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What are the prodromal features of rabies?

Earliest specific neurologic manifestation? 3 Ps

A

(+) fever, malaise, headache, n/v, anxiety, agitation

Paresthesis, Pain, Pruritus near the site of exposure (wound has healed at this point) but syptoms probably reflect infection with associated inflammatory changesin Local Dorsal Root Ganglion or Cranial Sensory Ganglia

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Cardinal Features of ENCEPHALITIC RABIES

What causes these?

A

Hyperexcitability, Hydrophobia, Aerophobia

classic features d/t dysfunction of infected
brainstem neurons= exaggerated defense reflexes

  1. Hydrophobia - involuntary, painful contraction of the DIAPHRAGM and accessory respiratory, laryngeal and pharyngeal muscles in response to swallowing liquids
  2. Aerophobia - same features caused by stimulation from a draft of air.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What causes foaming at the mouth?

A

Hypersalivation (ANS dysfunction) + Pharyngeal Dysfunction (foaming at the mouth)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What about Paralytic Rabies?

A

In paralytic rabies, muscle weakness predominates and cardinal features of encephalitic rabies (hyperexcitability, hydrophobia, and aerophobia) are lacking

Patients with paralytic rabies generally survive a few days longer (2-10 days) than those with encephalitic rabies (2-7 days), but multiple organ failure nevertheless ensues.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Diagnostics for Rabies

A

Currently, there is no diagnostic tool available which is economically suitable in our country to confirm rabies and only supportive care is given once acute neurologic disease has ensued.

In an ideal setting, RT PCR Amplification is highly sensitive and specific test to detect rabies virus RNA in fresh saliva samples, CSF and brain tissue

Direct Fluorescent Antibody Test - GOLD STANDARD **

Also a highly sensitive and specific test employing the use of rabies virus antibodies conjugated to fluorescent dyes

It is used to detect rabies antigen in skin biopsies and brain tissue. The utility of these diagnostic tests in patients with obvious signs and symptoms of rabies is generally low considering the outcome of the disease

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

How to manage rabies?

A

A palliative approach is typically pursued in patients who are unlikely to survive or who would not accept survival with severe neurologic sequelae.

  1. QUIET ROOM
  2. BENZOS > Physical Restraints
  3. IV MORPHINE - analgesia
  4. SCOPOMAINE - salivation
  5. ANTIPYRRECTICS - fever
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What do other countries do for a more aggressive approach?

A

MILWAUKEE PROTOCOL or WISCONSIN PROTOCOL which starts by putting the patient into chemically-induced coma using high-dose anesthetic agents as well as use of multiple intrathecal anti-viral drugs.

Cases of survival, however with moderate to severe neurologic sequelae.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

PREVENTION of RABIES

A
  1. Wound must be vigorously washed and flushed with soap and water for at least 10 minutes (betadine can also be used but soap and water pinakaeffective)
  2. frankly infected open wounds, ANTIBIOTICS may be started. CO-AMOXICLAV or CEFUROXIME
  3. Tetanus Toxoid also
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Things to consider in Post Exposure Prophylaxis

A

Effective ONLY during the Incubation period (20-90 days)
→ Given when the virus is still localized in the muscle. If given during the prodromal period and beyond, you can no longer save the patient.
→ If immunization status is unrecalled, consider unimmunized.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

rabies wound categorization is categorize I, II, III

A

Category I - lick/nibbling of intact skin
Category II - minor non-bleeding
Category III - sponatenous bleeding, licks through eyes or mucous membranes

17
Q

Rabies Vaccine PEP Schedule and Dose

A

Day 0,3,7,14 - ID or IM
Purified VeroCell: 0.1 mL
Purified Chick-Embryonal: 0.1 mL

18
Q

Rabies Immunoglobulin (kanino ito binibigay?)
Site of administration
Til when lang pwede ibigay ang RIg???

A

Single Dose for Category III wounds
NOT given >7 days post-exposure
GIVEN AT SEPARATE SITE FROM RABIES VACCINE - do not given antigen & antibody at the same site

Deltoid area
Equine derived RIG - 40 U/kg (first-line because cheaper, DO SKIN TEST)
Human derived RIG - 20 U/kg (special population such as Pregnant, HIV, immunocomp)

19
Q

PREVENTION:
1. Pre-exposure vaccination for occupational or recreational risk

  1. May Pre-Exposure na and was bitten
  2. Booster Monitoring
A
  1. Doses on Days 0, 7, 21, 28 Given IM***
  2. Booster at Day 0 and 3 (No RIg)
  3. Serum neutralizing antibody test help determine the need for subsequent booster doses - Needs booster dose when titre falls below 0.5 IU/mL
20
Q

Whatifthepatientisaveterinarianwhohasacomplete
vaccination of 3 doses and got bitten?
→ He may be previously immunized he was bitten

A

Booster dose day 0 and 3; No RIG

21
Q

Is there a need for PrEP if the pet or animal is already vaccinated for anti rabies?

A

→ Yes. There is still need for high-risk individuals. If no PrEP was administered, they will need PoEP