Postexposure Prophylaxis

If the species is unlikely to be infected with rabies, treatment may be deferred pending the outcome of a laboratory diagnosis, provided that no more than 48 hours transpires before the results are available. The WHO has given recommendations and separated the risks into categories (see Table 31.5). If a biting dog is more than a year old and has a vaccination certificate indicating that it has received at least 2 doses of a potent vaccine, the first not earlier than 3 months of age and another within 6 to 12 months, the bitten patient may not need treatment and the dog should be observed for 10 days. If the dog shows any signs of illness, the patient should receive prophylaxis (30-31).

Vaccines and rabies immunoglobulin are available around the world for intrawound, intramuscular and intradermal administration. They include:

Human diploid cell vaccine (HDCV) (preferred) Purified vero cell vaccine (PVRV) Purified chick embryo vaccine (PCEV) Purified duck embryo vaccine (PDEV) Human rabies immunoglobulin (HRIG) Equine rabies immunoglobulin (ERIG)

Before administrating any vaccine, the physician should carefully read the product insert or local health department information as vaccines and dosage regimens vary around the world. The intradermal route is more effective than

Table 31.5. WHO risk categories for rabies prophylaxis.

Category Exposure history Action

Table 31.5. WHO risk categories for rabies prophylaxis.

Category Exposure history Action

I

Touching or feeding of animals

No prophylaxis

Licks on intact skin

II

Nibbling of uncovered skin

Administer vaccine

Minor scratches or abrasions without bleeding

Licks on broken skin

III

Single or multiple transdermal bites or scratches

Rabies immunoglobulin

Contamination of mucous membrane with saliva (licks)

Vaccine

Source: Data from World Health Organization (31).

Source: Data from World Health Organization (31).

intramuscular. Pregnancy and infancy are never contraindications to postexposure rabies vaccination. In high risk bites and endemic areas, initiation of treatment should never await the results of a laboratory diagnosis. The vaccination schedule recommended by the World Health Organization is given in Table 31.6 (30,31).

People who have been previously vaccinated for rabies as a preventative measure or have had the series before must still receive a post-exposure vaccination, but not RIG. One dose is given at 0 and 3 days. Full treatment should be given to persons who received pre- or post-exposure treatment with vaccines of unproven potency and those who have not demonstrated acceptable rabies neutralizing antibody titer (30,31).

Table 31.6. Rabies vaccination schedule.

The intramuscular schedule for modern tissue-culture and duck embryo vaccines is:

Essen regimen: one dose of the vaccine administered on days 0, 3, 7, 14, and 28, given in the deltoid in adults or the anteriolateral thigh in children.

Alternative: 2 doses are given on day 0, followed by one dose on day 7 and day 21.

The intradermal schedule for modern vaccines is:

1. 2-site intraadermal method (PVRV and PDEV)

Days 0, 3, 7: 1 intradermal dose of vaccine is given at each of 2 sites.

Days 28 and 90: 1 dose given in one site.

2. 8-site intradermal method (HDCV and PCEC)

Day 0: 0.1 ml of vaccine given at each of 8 sites using the contents of the whole vial.

Day 7: 0.1ml given at 4 sites over deltoids and thighs.

Day 28 and 90: vaccine given at one site in deltoid (30,31).

The method of administration of rabies immunoglobulin (RIG) is as follows: Dose: 20 iu/kg body weight of HRIG Or 40 iu/kg of ERIF

Infiltrate the wounds using sterile saline to dilute it 2- to 3-fold. Any remainder should be injected in the anterior thigh. A skin test may be performed, but a negative result does not assure lack of an immune reaction.

Source: Data from World Health Organization (31).

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