Rabies

Question 1

A rapidly progressive, acute infectious disease of the CNS in humans and animals caused by rabies virus

Answer 1

Rabies

Question 2

What are the forms of rabies?

Answer 2

Rabies has encephalitic and paralytic forms.

Question 3

What family does the rabies virus belong to?

Answer 3

family Rhabdoviridae

Question 4

What type of genome does the rabies virus have?

Answer 4

a single-strand RNA genome, nonsegmented, negativesense (antisense) with 11,932 nucleotides.

Question 5

What is the incubation period of rabies?

Answer 5

usually 20–90 days, but it can be as short as a few days or over a year in rare cases

Question 6

How does rabies virus spread to the CNS?

Answer 6

Rabies virus spreads centripetally along peripheral nerves toward the spinal cord or brainstem via retrograde fast axonal transport, with delays at intervals of ~12 h at each synapse.

Question 7

What happens once the rabies virus enters the CNS?

Answer 7

Once the virus enters the CNS, it rapidly disseminates to other regions of the CNS via fast axonal transport along neuroanatomic connections.

Question 8

What occurs after CNS infection is established in rabies?

Answer 8

After CNS infection becomes established, there is centrifugal spread to other tissues, including the salivary glands, heart, adrenal glands, and skin.

Question 9

How is rabies virus secreted in rabid animals?

Answer 9

Rabies virus replicates in acinar cells of the salivary glands and is secreted in the saliva of rabid animals.

Question 10

Microglial nodules observed in the CNS in rabies

Answer 10

Babes nodules

Question 11

The most characteristic pathologic finding in rabies, which are eosinophilic cytoplasmic inclusions in brain neurons.

Answer 11

Negri body

Question 12

Where are Negri bodies commonly observed?

Answer 12

Purkinje cells of the cerebellum
pyramidal neurons of the hippocampus

Question 13

How does rabies generally present?

Answer 13

atypical encephalitis with relative preservation of consciousness.

Question 14

What are the prodromal features of rabies?

Answer 14

nonspecific symptoms like fever, malaise, headache, nausea, vomiting, and sometimes anxiety or agitation.

Question 15

What are the earliest specific neurologic symptoms of rabies?

Answer 15

paresthesias, pain, or pruritus near the site of exposure, occurring in 50–80% of patients.

Question 16

What are the two acute neurologic forms of rabies seen in humans?

Answer 16

encephalitic (furious) form in 80% of cases
paralytic form in 20% of cases

Question 17

What distinguishes encephalitic rabies?

Answer 17

early brainstem involvement, resulting in classic features of hydrophobia and aerophobia, and episodes of hyperexcitability followed by periods of complete lucidity

Question 18

What is responsible for the appearance of ‘foaming at the mouth’ in rabies?

Answer 18

The combination of hypersalivation and pharyngeal dysfunction

Question 19

cardinal features of encephalitic rabies

Answer 19

hyperexcitability
hydrophobia
aerophobia.

Question 20

What are common findings in cerebrospinal fluid (CSF) examination in rabies?

Answer 20

mild mononuclear-cell pleocytosis with a mildly elevated protein level

Question 21

What does an electroencephalogram typically show in rabies?

Answer 21

nonspecific abnormalities

Question 22

What do imaging tests show in rabies?

Answer 22

CT head scans are usually normal
MRI brain scans may show signal abnormalities in the brainstem or other gray-matter areas, but these findings are variable and nonspecific.

Question 23

How is a skin biopsy for rabies diagnosis performed?

Answer 23

Skin biopsy relies on the demonstration of rabies virus antigen in cutaneous nerves at the base of hair follicles, so samples are usually taken from hairy skin at the nape of the neck.

Question 24

In what clinical situations should rabies be considered?

Answer 24

Rabies should be considered in patients presenting with acute atypical encephalitis or acute flaccid paralysis, including cases where Guillain-Barré syndrome is suspected.

Question 25

Direct Fluorescent Antibody Testing is highly sensitive and specific for detecting rabies virus antigen in ___

Answer 25

🧻 (from skin biopsy and brain 🧻)

Question 26

There is no established treatment for rabies. T/F

Answer 26

True

Question 27

Rabies is an almost uniformly fatal disease. T/F

Answer 27

True

Question 28

PEP is not necessary if the animal remains healthy for 10 days T/F

Answer 28

True

Question 29

What constitutes PEP for rabies?

Answer 29

PEP includes
local wound care
active and passive immunization
washing bite wounds and scratches thoroughly with soap and water
debriding devitalized tissues, giving tetanus prophylaxis
initiating antibiotic treatment when indicated

Question 30

When should RIG be administered if not immediately available?

Answer 30

If RIG is not immediately available, it should be administered no later than 7 days after the first vaccine dose.

Question 31

Who should receive passive immunization with rabies immune globulin (RIG)?

Answer 31

Previously unvaccinated persons should be passively immunized with rabies immune globulin (RIG), but not those who have previously been immunized.

Question 32

How should the RIG dose be administered?

Answer 32

The entire dose of RIG (20 IU/kg) should be infiltrated at the site of the bite, and any remaining RIG should be administered IM at a distant site.

With multiple or large wounds, RIG may need to be diluted for adequate infiltration.

Question 33

(RIG) What should be done if the exposure involves a mucous membrane?

Answer 33

entire dose should be administered IM

Question 34

What precautions should be taken regarding rabies vaccine and RIG administration?

Answer 34

Rabies vaccine and RIG should never be administered at the same site or with the same syringe.

Question 35

What is the recommended dosage and administration site for rabies vaccine?

Answer 35

Four 1-mL doses of rabies vaccine should be given IM in the deltoid area (or anterolateral thigh in children)

Question 36

When should the rabies vaccine doses be administered?

Answer 36

The first dose should be given as soon as possible after exposure, followed by additional doses on days 3, 7, and 14. A fifth dose on day 28 is no longer recommended.

Question 37

Pregnancy is a contraindication for immunization T/F

Answer 37

False

Question 38

What can be used if human RIG is unavailable?

Answer 38

purified equine RIG can be used at a dose of 40 IU/kg