3 Rabies

Question 1

typical incubation period of rabies

Answer 1

20 to 90 days

no diagnostic test is available during the incubation period that will indicate rabies infection

Question 2

the rabies virus binds to the

Answer 2

nicotinic acetylcholine receptor in muscle, which is expressed on the postsynaptic membrane of the the neuromuscular junction

Question 3

bites to which body parts carry the highest risk

Answer 3

bites to the face and hands
but the site of the bite does not influence the decision to begin therapy

Question 4

Remarks on petting a rabid animal

Answer 4

Petting a rabid animal or contact with blood, urine, or feces (e.g., guano) of a rabid animal does not constitute an exposure and is not an indication for prophylaxis

Question 5

Preexposure prophylaxis

Answer 5

primary:
HDCV (human diploid cell vaccine) or PCECV (purified chick embryo cell culture vaccine) 1.0 mL IM (deltoid area), on days 0, 7, and 21 or 28

booster:
HDCV or PCECV 1.0 mL IM (deltoid), one dose on day 0 only

Question 6

animals in whom 10-days observation may be done

Answer 6

dogs, cats, ferrets

Question 7

animals that are regarded as rabid unless animal proven negative for rabies virus by laboratory tests

Answer 7

skunks, raccoons, foxes and most other carnivores;
bats

The animal should be euthanized and tested as soon as possible. Holding for observation is not recommended.

Question 8

animals that almost never require rabies postexposure prophylaxis

Answer 8

squirrels and chipmunks
hamsters and guinea pigs
mice and rats
rabbits and hares

Question 9

wound cleansing via

Answer 9

soap and water and a dilute solution of povidone-iodine (1mL povidone-iodine in 9 mL of water or NS)

Question 10

Postexposure prophylaxis for those not previously immunized

Answer 10

If Category 2:
HDCV OR PCECV 1mL IM deltoid area, one dose on days 0, 3, 7, 14,
also on D28 for immunocompromised

if Category 3:
give also HRIG 20 IU/kg actual body weight
- infiltrate the full dose around the wound(s) and give any remaining volume IM at an anatomic site distant from vaccine administration

Question 11

Postexposure prophylaxis for those previously immunized

Answer 11

HRIG should not be administered

HDCV / PCECV 1mL deltoid area , one dose on days 0 and 3
2 doses only

Question 12

HDCV / PCECV should be given where?

Answer 12

deltoid
younger children: anterolateral aspect of thigh may be used

should never be administered in the gluteal area - with reports of vaccine failure

Question 13

WHO categories of rabies exposure

Answer 13

Category I
touching or feeding animals
licks on intact skin
(i.e., no exposure)

Category II
nibbling of uncovered skin
minor scratches or abrasions without bleeding

Category III
single or multiple Transdermal bites or scratches
contamination of Mucous membrane with saliva from licks
licks on Broken skin
exposure to Bats

Question 14

Postexposure prophylaxis in immunocpromosed persons

Answer 14

vaccine: 5-dose schedule (0,3,7,14,28)

HRIG: same

Question 15

drugs that may interefere with the antibody response to intradermal rabies vaccine

Answer 15

chloroquine
mefloquine

when used as preexposure prophylaxis in travel, the rabies preexposure vaccination series should be completed before beginning chloroquine

Question 16

remarks on steroids and rabies

Answer 16

In animal models, use of corticosteroids shortens the incubation time and increases mortality, and for this reason, steroids are contraindicated

Question 17

rabies in pregnants

Answer 17

adverse pregnancy outcomes or fetal abnormalities have not been associated with rabies vaccination

pregnancy is not considered a contraindication to rabies pre/postexposure prophylaxis or HRIG

Question 18

rabies in children

Answer 18

dose of vaccine is same

dose of HRIG is actual weight-based. so for small children, calculated dose may be insufficient to infiltrate all wounds.
in such cases, sterile saline may be used to dilute the volume twofold or threefold to permit thorough infiltration

Question 19

HRIG administration

Answer 19

1) 20 IU/kg actual* body weight

2.) should be given ASAP (same time with first dose of rabies vaccine), preferable within 24 hours
If not done, can still be given up to 7 days after the first dose of vaccine. beyond that, antibody response to immunization should have occurred

3.) HRIG only administered once, at the beginning of rabies prophylaxis.
not given in previously immunized patients

4.) not given in those with IgA deficiencies, because small amounts of IgA may be present in HRIG and can cause severe allergic reaction

Question 19

contraindication to PCECV

Answer 19

severe eggallergy

Question 20

pathognomonic signs of rabies

Answer 20

hydrophobia
attempts to drink fluids result in severe spasms of the pharnyx, larynx, and diaphragm

aerophobia
precipitating grimacing and other signs by blowing air on the patient’s face

Question 21

remarks on treatment of rabies

Answer 21

no specific therapy has been of demosntrated benefit in clinical rabies

Question 22

remarks on survival from rabies

Answer 22

almost always fatal

only 14 patients are known to have survived rabies

survival with normal neurologic function was reported for a 15 y/o girl in whom coma was induced and treatment with ketamine, midazolam, ribavirin, and amantadine was provided
however, similar regimens have been used for more than 30 other patients without success

Question 23

Rabies vaccines

Answer 23

HDCV (human diploid cell vaccine)
PCECV (purified chick embryo cell culture vaccine)