Where should Immunoglobulin (IG) be injected for rabies exposure in the absence of a puncture wound?

Rabies Immunoglobulin Administration in the Absence of a Puncture Wound

When there is no visible puncture wound from a rabies exposure, rabies immunoglobulin (RIG) should be administered intramuscularly at a site distant from vaccine administration. 1

Understanding Rabies Post-Exposure Prophylaxis Components

Rabies post-exposure prophylaxis (PEP) consists of:

1. Thorough wound cleansing
2. Rabies immunoglobulin (RIG) administration
3. Rabies vaccination series

RIG Administration Guidelines

The administration of RIG depends on the presence or absence of identifiable wounds:

• With visible wounds: The CDC and WHO recommend infiltrating RIG in and around the wound(s) with any remaining volume injected intramuscularly at a site distant from vaccine administration 1
• Without visible wounds: When no puncture or wound is present, the full dose of RIG should be administered intramuscularly at a site distant from vaccine administration 1

Dosing and Administration Details

• RIG dose: 20 IU/kg body weight 1, 2
• Timing: Given at the time of the first vaccine dose (day 0) or up to day 7 if not given initially 1
• Administration site when no wound is present: Intramuscular injection, typically in the gluteal region or other site distant from vaccine administration 1

Important Considerations

• The primary purpose of RIG is to provide immediate passive immunity while the vaccine stimulates active immunity
• RIG should never be administered in the same anatomical site as the vaccine to prevent interference with active immunity development 1
• Recent evidence suggests that local wound infiltration is the primary mechanism of protection 3, but this obviously applies only when wounds are present
• Studies have shown that systemic administration of RIG alone results in very low circulating antibody levels 4, emphasizing the importance of local infiltration when wounds are present

Vaccination Schedule

Regardless of RIG administration method, the vaccination schedule remains:

• For immunocompetent individuals: 4 doses of rabies vaccine (1.0 mL each in the deltoid) on days 0,3,7, and 14 1
• For immunocompromised individuals: 5 doses on days 0,3,7,14, and 28 1

Common Pitfalls to Avoid

1. Delaying treatment: PEP should begin as soon as possible after exposure, ideally within 24 hours 1
2. Administering RIG at the same site as the vaccine: This can interfere with vaccine efficacy
3. Omitting RIG: Even without visible wounds, RIG is a crucial component of PEP for previously unvaccinated individuals
4. Incorrect dosing: Always calculate based on 20 IU/kg body weight, regardless of administration route 1, 2
5. Failing to consult public health officials: When in doubt about exposure risk or management, consultation with local or state public health officials is recommended 1