Failure of multiple-site intradermal postexposure rabies vaccination in patients with human immunodeficiency virus with low CD4+ T lymphocyte counts.

Human immunodeficiency virus (HIV)-infected patients with low CD4(+) T lymphocyte counts had a poor neutralizing antibody response to pre- and postexposure rabies vaccination. This study of HIV-infected patients with CD4(+) T lymphocyte counts < 200/microL indicated that patients had a poor response after 4-site intradermal vaccinations (4-4-4-0-2-2, doubling the intradermal doses of cell-culture rabies vaccine).

Failure of pre- and postexposure rabies vaccinations in a child infected with HIV.

We report the case of a 6-y-old HIV-infected girl with severe immune deficiency who failed to respond to intramuscular pre-exposure rabies vaccination using human diploid cell rabies vaccine on days 0, 7 and 28. She also failed to respond to an intradermal postexposure rabies regimen using purified verocell rabies vaccine at 4 sites on days 0, 3 and 7 and at 2 sites on days 30 and 90 (double the usual regimen). Sequentially monitored rabies neutralizing antibody titers were below the WHO minimum acceptable level (> 0.15 IU/ml) in all specimens. Rabies prevention in HIV-infected persons with severe immune suppression requires further study.

Immunogenicity of rabies postexposure booster injections in subjects who had previously received intradermal preexposure vaccination.

BACKGROUND: Preexposure rabies vaccination is recommended using the full dose intramuscular or less expensive reduced dose intradermal method. The reliability of the reduced dose intradermal preexposure regimen is still controversial. The objective of this study was to determine whether it will mount a predictable accelerated immune response after a simulated rabies exposure. METHOD: One hundred and thirty-eight veterinary students received intradermal or intramuscular preexposure vaccination using a potent batch of purified chick embryo rabies vaccine. They then received booster injections one year later. RESULTS: Subjects who received intradermal rabies preexposure vaccination, using 0.1 mL of a potent tissue culture vaccine on days 0, 7, and 28, had a lower postexposure booster antibody response 1 year later than subjects given the preexposure series intramuscularly. A significant number showed an unsatisfactory early anamnestic response. Residual neutralizing antibodies, 1 year after the intramuscular preexposure series, were also significantly higher in the intramuscular than in the 0.1 mL dose intradermal group. However, all study subjects had antibody titers above the minimum recommended level of 0.5 IU/mL by day 14. CONCLUSIONS: We conclude that not all subjects who received an intradermal preexposure vaccine series may be fully protected during the first 5 days after an exposure. Rabies immune globulin, injected into bite wounds and followed by a complete postexposure vaccine series, may be indicated if such a patient experiences a severe rabies exposure.

Immune response to simulated postexposure rabies booster vaccinations in volunteers who received preexposure vaccinations.

Several studies of the efficacy of intradermal postexposure rabies vaccination have shown that this procedure is safe, effective, and cost saving. Less is known about the reliability of the present World Health Organization (WHO)-approved intradermal preexposure regimen, which consists of three 0.1-mL doses that are generally given on days 0, 7, and 28. Previous studies have shown that neutralizing antibody responses are lower and of shorter duration in subjects given the reduced-dose intradermal regimen. Thus, it is still uncertain whether the WHO-recommended single intramuscular or intradermal booster injections given on days 0 and 3 would prevent death in all cases. In this preliminary study, we evaluated titers of neutralizing antibody in Thai student volunteers given two simulated postexposure boosters, as recommended by WHO, and we compared these volunteers to a group given vaccine intramuscularly. We observed a lower, although adequate, accelerated immune response in those given the preexposure series and postexposure boosters intradermally.

Value of skin testing for predicting reactions to equine rabies immune globulin.

The high cost of postexposure prophylaxis for rabies is one reason that treatment is inadequate in developing countries. This problem has kindled interest in the use of equine rabies immune globulin, which is a less expensive, yet effective, substitute for human rabies immune globulin. Fatal anaphylaxis is a feared complication of the administration of heterologous serum; therefore, authoritative sources recommend prior skin testing. However, recommendations for methods of administering such a skin test and for its interpretation vary greatly. We embarked on a long-term study to develop guidelines for administration and interpretation of skin test results and to eventually determine a cost-benefit ratio. The skin test is not predictive of serum sickness. Anaphylaxis is rare with modern purified and pepsin-digested equine rabies immune globulins. We consider a skin test to be positive only if a wheal of > 10 mm in diameter, with or without flare, or a wheal of 5-10 mm in diameter with a flare of > 20 mm develops. Long-term studies will be required to answer the remaining questions regarding test criteria and cost benefits.