Health Advisory
RABIES MANAGEMENT UPDATE

The Delaware Division of Public Health (DPH) is issuing this advisory to health care providers in Delaware as a follow-up to a press release that was sent out encouraging residents to take steps to protect themselves from rabies.

Rabies remains endemic in Delaware. In 2007, DPH performed 216 rabies tests in animals that may have potentially exposed humans to the disease and confirmed rabies in eleven of these animals (three cats, one fox, four raccoons and three skunks). Since January 2008, DPH has performed rabies tests on 112 animals that potentially exposed a human and nine of these animals have tested positive.

Since DPH only tests animals for rabies when there is potential human exposure, there may be many more infected wild animals than suggested by the numbers quoted hence the need for a prevention message

Treatment of Wounds

Regardless of the risk for rabies, medical treatment of animal bite wounds includes the recognition and treatment of serious injury (e.g., nerve or tendon laceration), avoidance or management of infection (both local and systemic), and approaches that will yield the best possible cosmetic results. For many types of bite wounds, immediate gentle irrigation with water or a dilute water povidone-iodine solution markedly decrease the risk for bacterial infection. Care should be taken not to damage skin or tissues. Wound cleansing is especially important in rabies prevention because thorough wound cleansing alone without other post exposure prophylaxis markedly reduce the likelihood of rabies in animal studies. A booster dose of tetanus vaccine should be considered. The use of antibiotic prophylaxis and primary wound closure should be individualized on the basis of the exposing animal species, size and location of the wound(s), and time interval since the bite. Suturing should be avoided, when possible.

Vaccination

Administration of rabies post exposure prophylaxis is a medical urgency, not a medical emergency. Providers are reminded that though there is sufficient vaccine available for rabies post-exposure prophylaxis, rabies vaccine is currently in short supply and a risk assessment weighing potential likelihood versus the actual risk for the person acquiring rabies should be conducted in each situation involving a possible rabies exposure. Providers should first consult with the Division of Public Health’s Rabies Program (302-744-4545) before rabies post exposure prophylaxis is initiated. The program may assist in determining the risk of rabies exposure through epidemiological assessment, quarantine or laboratory testing of the offending animal, the results of which may preclude the need for post exposure prophylaxis.

Post exposure anti-rabies vaccination should always include administration of both passive antibody and vaccine, with the exception of persons who have ever previously received complete vaccination regimens (pre-exposure or post-exposure) or persons who have been vaccinated with other types of vaccines and have previously had a documented rabies virus neutralizing antibody titer. These persons should receive only the vaccine.

The combination of Human Rabies Immune Globulin (HRIG) and vaccine is recommended for both bite and non-bite exposures regardless of the interval between exposure and initiation of prophylaxis. If post-exposure prophylaxis has been initiated and appropriate laboratory diagnostic testing (i.e., the direct fluorescent antibody test) indicates that the exposing animal was not rabid, post-exposure prophylaxis can be discontinued.

HRIG Use

HRIG is administered only once (i.e., at the beginning of anti-rabies prophylaxis) to previously unvaccinated persons to provide immediate, passive, rabies virus-neutralizing antibody coverage until the patient responds to the rabies vaccine by actively producing antibodies. If HRIG was not administered when vaccination was begun (i.e., day 0), it can be administered up to and including day 7 of the post-exposure prophylaxis series. Beyond the seventh day, HRIG is not indicated because an antibody response to cell culture vaccine is presumed to have occurred. Because HRIG can partially suppress active production of antibody, the dose administered should not exceed the recommended dose. The recommended dose of HRIG is 20 IU/kg (0.133 mL/kg) body weight. This formula is applicable to all age groups, including children. If anatomically feasible, the full dose of HRIG should be thoroughly infiltrated in the area around and into the wounds. Any remaining volume should be injected IM at a site distant from vaccine administration.

Vaccine Use

Two rabies vaccines are available for use in the United States (Imovax® and RabAvert®); either can be administered in conjunction with HRIG at the beginning of post exposure prophylaxis. A regimen of 5 one-mL doses of HDCV or PCECV should be administered IM to previously unvaccinated persons. The first dose of the 5-dose course should be administered as soon as possible after exposure. This date is then considered day 0 of the post exposure prophylaxis series. Additional doses should then be administered on days 3, 7, 14, and 28 after the first vaccination. For adults, the vaccination should always be administered IM in the deltoid area. For children, the anterolateral aspect of the thigh is also acceptable. The gluteal area should never be used for HDCV or PCECV injections because administration of HDCV in this area results in lower neutralizing antibody titers.

Please call the Rabies program Hotline at (302) 744-4545 if you need additional information.