Imovax Rabies is a vaccine indicated for pre-exposure and
post-exposure prophylaxis against rabies. Imovax Rabies vaccine is approved for
use in all age groups.
Rationale Of treatment
Physicians must evaluate each possible rabies exposure.
Local or state public health officials should be consulted if questions arise about
the need for prophylaxis.11
The following factors should be considered before
antirabies prophylaxis is initiated.
Species of biting animal
Rabid bats have been documented in the 49 continental
states, and bats are increasingly implicated as important wildlife reservoirs
for variants of rabies virus transmitted to humans. Transmission of rabies
virus can occur from minor, seemingly underappreciated or unrecognized bites
from bats (see Table 2).11
Wild Terrestrial Carnivores
Raccoons, skunks, and foxes are the terrestrial
carnivores most often infected with rabies in the United States. Suggestive
clinical signs of rabies among wildlife cannot be interpreted reliably. All
bites by such wildlife should be considered possible exposures to rabies virus.
Post-exposure prophylaxis should be initiated as soon as possible following exposure
to such wildlife, unless the animal is available for diagnosis and public
health authorities are facilitating expeditious laboratory testing, or if the
brain tissue from the animal has already tested negative (see Table 2).11
Other Wild Animals
Small rodents (eg, squirrels, chipmunks, rats, mice,
hamsters, guinea pigs, and gerbils) and lagomorphs (including rabbits and
hares) are rarely infected with rabies and have not been known to transmit
rabies to humans. In all cases involving rodents, the state or local health
department should be consulted before a decision is made to initiate
post-exposure prophylaxis (see Table 2).11
Domestic Dogs, Cats, and Ferrets
The likelihood of rabies in a domestic animal varies regionally,
and the need for post-exposure prophylaxis also varies on the basis of regional
epidemiology (see Table 2).11
Circumstances Of Biting Incident
An unprovoked attack might be more likely than a provoked
attack to indicate the animal is rabid. Bites inflicted on a person attempting
to feed or handle an apparently healthy animal should generally be regarded as
provoked. Consult the local or state health department following a provoked or
unprovoked exposure to determine the best course of action based on current
public health recommendations.
Type of exposure
Rabies is transmitted by introducing the virus into open
cuts or wounds in skin or via mucous membranes. The likelihood of rabies infection
varies with the nature and extent of exposure. Two categories of exposure
should be considered, bite and nonbite.
Any penetration of the skin by teeth.
Scratches, abrasions, open wounds, or mucous membranes
contaminated with saliva or other potentially infectious material, such as
brain tissue, from a rabid animal. Casual contact, such as petting a rabid
animal, (without a bite or nonbite exposure as described above), does not constitute
an exposure and is not an indication for prophylaxis. Rare reports of airborne
rabies have been received from laboratory and bat-infested cave settings.11
Rare cases of rabies from human-to-human transmission
have occurred in patients in the US and overseas who received organs
transplanted from persons who died of rabies undiagnosed at the time of death.
No documented laboratory-diagnosed cases of human-to-human rabies transmission have
been documented from a bite or nonbite exposure other than the transplant
cases. At least two cases of human-to-human rabies transmission in Ethiopia
have been suggested, but rabies as the cause of death was not confirmed by
laboratory testing. The reported route of exposure in both cases was direct
salivary contact from another human (ie, a bite and a kiss). Routine delivery
of health care to a patient with rabies is not an indication for post-exposure
prophylaxis unless the healthcare worker is reasonably certain that he or she
was bitten by the patient or that his or her mucous membranes or nonintact skin
was exposed directly to potentially infectious saliva or neural tissue.11
Pre- And Post-Exposure Prophylaxis Of Rabies
Pre-exposure immunization should be offered to rabies
researchers, certain laboratory workers and other persons in high-risk groups,
such as veterinarians and their staff, and animal handlers. Pre-exposure
vaccination also should be considered for persons whose activities bring them
into frequent contact with rabies virus or potentially rabid bats, raccoons,
skunks, cats, dogs, or other species at risk for having rabies. In addition,
some international travelers might be candidates for pre-exposure vaccination
if they are likely to come in contact with animals in areas where dog or other
animal rabies is enzootic and immediate access to appropriate medical care,
including rabies vaccine and immune globulin, might be limited.11
Vaccination is recommended for children living in or
visiting countries where exposure to rabid animals is a constant threat.
Worldwide statistics indicate children are more at risk than adults. Pre-exposure
prophylaxis is administered for several reasons. First, although pre-exposure vaccination
does not eliminate the need for additional medical evaluation after a rabies
exposure, it simplifies management by eliminating the need for Rabies Immune
Globulin (RIG) and decreases the number of doses of vaccine needed. This is
particularly important for persons at high risk for being exposed to rabies in
areas where modern immunizing products might not be available or where cruder,
less safe biologics might be used, placing the exposed person at increased risk
for adverse events. Second, pre-exposure prophylaxis might offer partial
immunity to persons whose post-exposure prophylaxis is delayed. Finally,
pre-exposure prophylaxis might provide some protection to persons at risk for
unrecognized exposures to rabies.11
Pre-Exposure Rabies Prophylaxis Guide
Pre-exposure prophylaxis consists of three 1.0 mL doses
of Imovax Rabies vaccine administered intramuscularly, using a sterile needle
and syringe, one injection per day on Days 0, 7, and 21 or 28. In adults and
older children, the vaccine should be administered in the deltoid muscle. In infants
and small children, the anterolateral aspect of the thigh may be preferable,
depending on age and body mass.
Administration of booster doses of vaccine depends on
exposure risk category and serologic testing as noted in Table 1.
Immunosuppressed persons should postpone pre-exposure
vaccinations and consider avoiding activities for which rabies pre-exposure
prophylaxis is indicated. When this course is not possible, immunosuppressed
persons who are at risk for rabies should have their viral neutralizing
antibody titers checked after completing the pre-exposure series. If no acceptable
antibody response is detected, the patient should be managed in consultation
with their physician and appropriate public health officials.11
Table 1: Rabies Pre-exposure Prophylaxis Guide11
||Nature of risk
||Virus present continuously and often in high concentrations. Specific exposures likely to go unrecognized. Bite, nonbite, or aerosol exposure.
||Rabies research laboratory workers; rabies biologics production workers.
||Primary course. Serologic testing every 6 months; booster vaccination if antibody titer is below acceptable level.*
||Exposure usually episodic, with source recognized, but exposure also might be unrecognized. Bite, nonbite, or aerosol exposure.
||Rabies diagnostic laboratory workers, cavers, veterinarians and staff, and animal-control and wildlife workers in areas where rabies is enzootic. All persons who frequently handle bats.
||Primary course. Serologic testing every 2 years; booster vaccination if antibody titer is below acceptable level.*
|Infrequent (greater than population at large)
||Exposure nearly always episodic with source recognized. Bite or nonbite exposure.
||Veterinarians and animal-control staff working with terrestrial animals in areas where rabies is uncommon to rare. Veterinary students. Travelers visiting areas where rabies is enzootic and immediate access to appropriate medical care including biologics is limited.
||Primary course. No serologic testing or booster vaccination.
|Rare (population at large)
||Exposure always episodic with source recognized. Bite or nonbite exposure.
||US population at large, including persons in areas where rabies is epizootic.
||No vaccination necessary.
|*Minimum acceptable antibody level is complete virus neutralization
at a 1:5 serum dilution by the rapid fluorescent focus inhibition test. A
booster dose should be administered if the titer falls below this level.
The essential components of rabies post-exposure
prophylaxis are wound treatment and, for previously unvaccinated persons, the
administration of both human rabies immune globulin (RIG) and vaccine.11
Local treatment of wounds
Thorough washing and flushing (for about 15 minutes, if possible)
with soap or a cleansing agent and copious amounts of water of all bite wounds
and scratches should be done immediately or as early as possible. Where
available, an iodinecontaining, or similarly viricidal, topical preparation
should be applied to the wound.12
Tetanus prophylaxis and measures to control bacterial
infection should be given as indicated.
The sooner treatment is begun after exposure, the better.
Post-exposure antirabies vaccination should always include administration of
both passive antibody and vaccine, with the exception of persons who have ever
previously received complete vaccination regimens (pre-exposure or
post-exposure) with a cell culture vaccine or persons who have been vaccinated with
other types of vaccines and have previously had a documented rabies virus
neutralizing antibody titer. These persons should receive only vaccine (ie,
post-exposure for a person previously vaccinated). The combination of RIG and
vaccine is recommended for both bite and nonbite exposures reported by persons
who have never been previously vaccinated for rabies, regardless of the
interval between exposure and initiation of prophylaxis. If post-exposure prophylaxis
has been initiated and appropriate laboratory diagnostic testing (ie, the
direct fluorescent antibody test) indicates that the exposing animal was not
rabid, post-exposure prophylaxis can be discontinued.11
Treatment outside the United States
If post-exposure is begun outside the United States with
locally produced biologics, it may be desirable to provide additional treatment
when the patient reaches the US. State or local health departments should be
contacted for specific advice in such cases.11
Post-Exposure Rabies Prophylaxis Guide
The following recommendations are only a guide. In
applying them, take into account the animal species involved, the circumstances
of the bite or other exposure, the vaccination status of the animal, the
availability of the exposing animal for observation or rabies testing, and the
presence of rabies in the region (see Table 2). Local or state public health
officials should be consulted if questions arise about the need for rabies
Table 2: Post-exposure Treatments Guide11
||Evaluation and disposition of animal
||Post-exposure prophylaxis recommendations
|Dogs, cats, and ferrets
||Healthy and available for 10 days observation.
Rabid or suspected rabid.
Unknown (eg, escaped).
|Persons should not begin prophylaxis unless animal develops clinical signs of rabies.*
Immediately begin prophylaxis.
Consult public health officials.
|Skunks, raccoons, foxes, and most other carnivores; bats †
||Regard as rabid unless animal proven negative by laboratory tests. ‡
||Consider immediate prophylaxis.
|Livestock, small rodents (rabbits and hares), large rodents (woodchucks and beavers), and other mammals
||Consult public health officials. Bites from squirrels, hamsters, guinea pigs, gerbils, chipmunks, rats, mice, other small rodents, rabbits, and hares almost never require anti-rabies postexposure prophylaxis.
|* During the 10-day observation period, begin
post-exposure prophylaxis at the first sign of rabies in a dog, cat, or ferret
that has bitten someone. If the animal exhibits clinical signs of rabies, it
should be euthanized immediately and tested.
† Post-exposure prophylaxis should be initiated as soon as possible following
exposure to such wildlife unless the animal is available for testing and public
health authorities are facilitating expeditous laboratory testing or it is
already known that brain material from the animal has tested negative. Other
factors that might influence the urgency of decision-making regarding
initiation of post-exposure prophylaxis before diagnostic results are known
include the species of the animal, the general appearance and behavior of the animal,
whether the encounter was provoked by the presence of a human, and the severity
and location of bites. Discontinue vaccine if appropriate laboratory diagnostic
test (ie, the direct fluorescent antibody test) is negative.
‡ The animal should be euthanized and tested as soon as possible. Holding for
observation is not recommended.