When is immunoglobulin administered after a tick bite? - briefly
Immunoglobulin for tick‑borne encephalitis is given as soon as possible, ideally within 48 hours after tick removal when the tick has been attached for ≥24 hours and the person is unvaccinated. It is indicated only in endemic areas where the individual lacks prior immunity.
When is immunoglobulin administered after a tick bite? - in detail
Immunoglobulin therapy after a tick bite is considered only when the bite is linked to a possible rabies exposure. The decision rests on three factors: confirmation that the tick has fed on a rabid animal, presence of saliva or neural tissue contact with the wound, and the unavailability of prior rabies vaccination.
The product—human rabies immune globulin (HRIG)—must be administered as soon as the exposure is identified. Guidelines specify injection within 24 hours of the event and no later than seven days after the bite, because the passive antibodies lose efficacy beyond this window. Early delivery maximizes neutralization of virus particles before they reach the peripheral nerves.
Administration protocol:
- Dose: 20 IU per kilogram of body weight, divided between the wound site and the remainder given intramuscularly at a separate location.
- Wound infiltration: as much HRIG as feasible is infiltrated around the entire bite area, ensuring direct contact with tissue.
- Systemic injection: the leftover volume is injected into a large muscle (e.g., deltoid) to provide circulating antibodies.
HRIG is combined with the active rabies vaccine series, which begins on day 0, followed by doses on days 3, 7, and 14 (or 28 for immunocompromised patients). Failure to give immunoglobulin promptly, or omission of the product when indicated, increases the risk of fatal encephalitis.
For tick bites unrelated to rabies, immunoglobulin is not indicated; prophylactic antibiotics for Lyme disease or supportive care are the standard approaches.