When is it necessary to administer immunoglobulin after a tick bite? - briefly
Specific immunoglobulin is indicated for individuals without prior TBE vaccination who are bitten by a tick confirmed or highly likely to carry the TBE virus, provided the bite occurred within 48 hours. It may also be considered for high‑risk patients (e.g., immunocompromised, pregnant) in endemic regions when immediate vaccination is not feasible.
When is it necessary to administer immunoglobulin after a tick bite? - in detail
Tick‑borne encephalitis (TBE) is the only disease for which passive immunisation with human immunoglobulin is recommended after a tick attachment. The decision to administer TBE‑immune globulin (TBE‑IG) depends on three principal factors: exposure risk, vaccination status, and host susceptibility.
High‑risk exposure includes bites in regions with documented TBE activity, especially during the peak transmission season, and attachment periods exceeding 24 hours. Multiple ticks attached simultaneously increase the probability of virus transmission and therefore raise the indication for immunoglobulin.
Vaccination status determines the need for passive prophylaxis. TBE‑IG is indicated when:
- the individual has never received any TBE vaccine dose,
- the vaccination series is incomplete (fewer than two doses) or the last dose was administered more than five years ago,
- the vaccine schedule cannot be completed promptly because of time constraints or medical contraindications (e.g., severe allergic reaction to vaccine components).
Host susceptibility modifies the recommendation. Immunoglobulin should be given to persons who cannot mount an adequate vaccine response, such as:
- patients receiving immunosuppressive therapy (chemotherapy, biologics, high‑dose steroids),
- individuals with primary immunodeficiency,
- pregnant or lactating women when vaccination is contraindicated,
- children under the age approved for active immunisation in the specific country.
Timing is critical. The passive antibody preparation must be injected as soon as possible after the tick is removed, ideally within 48 hours and no later than 72 hours, to achieve protective serum concentrations before the virus reaches the central nervous system.
Dosage recommendations vary by country, but the standard regimen consists of a single intramuscular dose of 250 IU/kg body weight, administered in the deltoid or gluteal muscle. No booster doses are required for the same exposure event.
In summary, passive immunisation after a tick bite is warranted only for TBE‑IG, and only when the bite occurs in a high‑incidence area, the victim is unvaccinated or inadequately vaccinated, and the host is unable to receive or respond to active vaccination. Prompt administration within two to three days maximises efficacy.