3 Rabies Flashcards
typical incubation period of rabies
20 to 90 days
no diagnostic test is available during the incubation period that will indicate rabies infection
the rabies virus binds to the
nicotinic acetylcholine receptor in muscle, which is expressed on the postsynaptic membrane of the the neuromuscular junction
bites to which body parts carry the highest risk
bites to the face and hands
but the site of the bite does not influence the decision to begin therapy
Remarks on petting a rabid animal
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
Preexposure prophylaxis
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
animals in whom 10-days observation may be done
dogs, cats, ferrets
animals that are regarded as rabid unless animal proven negative for rabies virus by laboratory tests
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.
animals that almost never require rabies postexposure prophylaxis
squirrels and chipmunks
hamsters and guinea pigs
mice and rats
rabbits and hares
wound cleansing via
soap and water and a dilute solution of povidone-iodine (1mL povidone-iodine in 9 mL of water or NS)
Postexposure prophylaxis for those not previously immunized
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
Postexposure prophylaxis for those previously immunized
HRIG should not be administered
HDCV / PCECV 1mL deltoid area , one dose on days 0 and 3
2 doses only
HDCV / PCECV should be given where?
deltoid
younger children: anterolateral aspect of thigh may be used
should never be administered in the gluteal area - with reports of vaccine failure
WHO categories of rabies exposure
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
Postexposure prophylaxis in immunocpromosed persons
vaccine: 5-dose schedule (0,3,7,14,28)
HRIG: same
drugs that may interefere with the antibody response to intradermal rabies vaccine
chloroquine
mefloquine
when used as preexposure prophylaxis in travel, the rabies preexposure vaccination series should be completed before beginning chloroquine
remarks on steroids and rabies
In animal models, use of corticosteroids shortens the incubation time and increases mortality, and for this reason, steroids are contraindicated
rabies in pregnants
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
rabies in children
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
HRIG administration
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
contraindication to PCECV
severe eggallergy
pathognomonic signs of rabies
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
remarks on treatment of rabies
no specific therapy has been of demosntrated benefit in clinical rabies
remarks on survival from rabies
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
Rabies vaccines
HDCV (human diploid cell vaccine)
PCECV (purified chick embryo cell culture vaccine)
