Rabies Guide 2010.pdf - the South African Veterinary Council

Human antirabies immunoglobulin
The administration of antirabies immunoglobulin
(RIG) complements rabies vaccination in situations
where viral transmission may have occurred, as
production of vaccine–induced neutralising antibodies
take seven to 10 days after vaccination. RIG is safe
and provides rapid passive immunity that persists
with a half-life of approximately three weeks. 111,112
The human RIG currently used in South Africa is
produced by fractionation of pooled serum from
immunised persons. The introduction of human RIG
proved a valuable replacement to the previously used
antirabies serum prepared in horses. Although the
latter was effective and is still used in many developing
countries, it may induce serum sickness. To ensure
potency, it is essential that RIG be maintained
between 2 and 8°C during handling and storage. All
patients who have received RIG should be observed
for an hour thereafter. An emergency pack for treating
anaphylaxis should be available.
The dosage of human RIG currently available in
South Africa is 20 International Units (IU) per kg
body-mass. 73 RIG is supplied in 2 ml ampoules with
a virus-neutralising antibody content of 300IU.
Preferably the complete dose of RIG should be
infiltrated into the depth of the wound or tissue
immediately adjacent to the wound. Where this
is not anatomically possible, the remaining RIG
may be injected intramuscularly into the deltoid
muscle. 113 RIG was traditionally administered into
the buttocks, but there is evidence of low circulating
rabies neutralising antibodies following RIG injection
into gluteal fat. With multiple wounds, where the
dose of RIG based on body mass is insufficient to
infiltrate all wounds, the dose must be diluted up
to 50% in saline to allow infiltration of all wounds.
Failure to infiltrate all wounds is believed to have
contributed to the deaths of a number of children. 114
Local anaesthetic agents should not be used to
facilitate RIG administration.
RIG is administered on the day of initial patient
presentation, traditionally referred to as day 0, with
the first dose of vaccine but at separate injection sites.
This is irrespective of the time elapsed since exposure,
which represents a departure from the previous
recommendation that RIG should only be given to
patients presenting within a week of exposure. 97 If RIG
is not available when vaccination is initiated, it may
be administered up to day 7 after the administration
of the first vaccine. RIG administration is not
recommended prior to vaccination, nor is it currently
recommended for individuals who have received
pre-exposure vaccination as it is believed that RIG
may interfere with the rapid anamnestic response to
vaccine.
Rabies vaccines
Rabies vaccine, when given post-exposure, induces
immunity within seven to 10 days. Two cell-culture
vaccines are currently registered for use in South
Africa, i.e. purified chick embryo cell culture vaccine
(PCECV) and purified Vero-cell rabies vaccine
(PRVR), and are highly purified and inactivated
vaccines that meet the WHO potency standard of
greater than or equal to 2,5 IU per dose.
All persons judged to be at high risk for rabies
exposure should be vaccinated, with treatment being
initiated as soon as possible even if there has been
a delay in presentation to the health service. The
treatment/prophylaxis schedules presented here are
based on the most recent WHO recommendations,
and are valid for the cell-culture vaccines registered
in South Africa. However, it must be emphasized
that the Essen intramuscular regimen is the only
recommended schedule and administration route
for South Africa, and expert advice should be sought
before using an alternative regimen. The vaccination
schedule may be discontinued if the suspected source
animal remains healthy for 10 days after the exposure
or if an approved veterinary laboratory reports the
brain specimen from the animal as negative. 41
38