eMedicine Specialties > Emergency Medicine > Infectious Diseases

Rabies: Treatment & Medication

Author: Mark A Merlin, DO, EMT-P, FACEP, Assistant Professor, EMS Medical Director, Department of Emergency Medicine, University of Medicine and Dentistry-Robert Wood Johnson Medical School; Medical Director, New Jersey EMS/Disaster Medicine Fellowship, New Jersey EMS Physician Response Program, New Jersey EMS Task Force; Chair of New Jersey Mobile Intensive Care Unit Advisory Council, New Jersey Department of Health and Senior Services
Coauthor(s): Peter W Pryor II, MD, MPH, Fellow in Emergency Medical Services/Disaster Medicine, Attending Physician, Department of Emergency Medicine, Robert Wood Johnson University Hospital, University of Medicine and Dentistry of New Jersey; John Bertolini, MD, Chair, Department of Emergency Medicine, Union Hospital; Raffi Kapitanyan, MD, Assistant Professor, Assistant Professor of Emergency Medicine, Emergency Medicine, Robert Wood Johnson University Hospital/UMDNJ
Contributor Information and Disclosures

Updated: May 11, 2009

Treatment

Prehospital Care

Prehospital care is supportive depending on the stage of the virus. Typically, patients present with an unknown febrile illness with signs of encephalitis. Body fluid isolation should take place for these patients.

Emergency Department Care

Treatment discussed here focuses on animal exposures where rabies transmission is a possibility. This is the primary concern of the emergency physician. Treatment of human rabies is supportive and often involves therapy for other possible etiologies before specific diagnosis is made, usually postmortem or well into an intensive care unit (ICU) hospitalization.

Most recent patients described in the literature were initially sent home by the emergency department. This reinforces the important role of a history of recent animal or bite exposures.

• Immediate therapy consists of thoroughly cleaning all bite and scratch wounds with soap and water and/or 2% benzalkonium chloride. Provide wound care as needed. Tetanus prophylaxis is indicated; measures to prevent bacterial infection when warranted also are indicated. A decision must then be made regarding postexposure prophylaxis.
• Postexposure rabies prophylaxis
• All unprovoked animal attacks are considered high risk for rabies.
• If a bite or mucus membrane contact was inflicted by a domestic animal with known vaccination status, and if the owner can quarantine the animal for 10 days, postexposure prophylaxis can be withheld.
• If signs of rabies occur, the animal (if captured) should be sacrificed and the head shipped to a qualified facility for testing. Regional poison control centers and local veterinarians are valuable resources regarding testing sites and procedures.
• Exposures involving small rodents and lagomorphs (eg, squirrels, hamsters, guinea pigs, gerbils, chipmunks, rats, mice, rabbits, hares) do not require treatment. These animals can be infected with rabies virus in the laboratory but have never been associated with rabies virus transmission to humans.
• Immediately treat bites or scratches from high-risk animals such as bats, raccoons, foxes, skunks, woodchucks, nondomestic dogs, or dogs near the United States–Mexican border.
• Data suggest that insignificant contact with bats may result in viral transmission. Postexposure prophylaxis for bats is recommended, even in the absence of a bite or scratch. Any suspicion of bat contact, such as finding a bat in a room where someone has been sleeping or any contact with an unattended child, intoxicated person, or mentally disabled person, requires postexposure prophylaxis.
• Human rabies immune globulin and vaccine are recommended for bites and exposures regardless of the period between exposure and treatment unless the individual is previously vaccinated and rabies antibodies can be detected. The average delay in the United States between exposure and treatment is 5 days, which does not appear to compromise successful prophylaxis.
• Although no human-to-human nontransplant transmission has been documented clearly, anyone coming into contact with CSF, saliva, or mucus membranes of a person suspected of having rabies should receive complete prophylaxis. According to the CDC, the average number of people who receive postexposure prophylaxis secondary to contact with a single suspected human rabies case is 64.6.
• Vaccines: The 2 rabies vaccines currently available in the United States are the human diploid cell vaccine (HDCV, Imovax) and RabAvert (rabies vaccine produced by Chiron). They are equal in efficacy and safety.
• The vaccine takes 7-10 days to induce an active immune response, with immunity lasting approximately 2 years. Administer the vaccine in the deltoid region, with a dose of 1 mL on days 0, 3, 7, 14, and 28.
• Slight erythema may be expected, but any further skin changes should be reported to the health department to determine actual necessity of vaccine.
• For young children, outer aspect of the thigh may be used for injection. Do not administer in the gluteal area because of possible poor absorption if accidentally administered subcutaneously.
• Passive immunization with human rabies immune globulin (HRIG, Hyperab) provides immediate protection with a serum half-life of 21 days.
• Administer rabies immune globulin (20 IU/kg) with as much of the dose as possible infiltrated in and around the wound (if wound location allows); administer the rest intramuscularly in the gluteal region, using a needle long enough to ensure an intramuscular injection. The syringes and needles used for vaccine and immune globulin should be different.
• Case reports have documented safe administration of HRIG and HDCV during pregnancy.
• In immunocompromised persons, measure serum antibodies to determine adequate immune response. Rabies immunoglobulin should be delivered in the same dosage. Immediate cleaning with soap and water is the most important way of decreasing rabies transmission in these patients.
• Neural tissue rabies vaccines should no longer be used, although they may be still used in some developing countries. In countries that cannot afford the 5-dose regimen, the World Health Organization states that 2 regimens are available which fulfill their requirements. These have been used in developing countries as replacements for the more expensive injections. These injections should be administered in consultation with the CDC  
• No postexposure vaccine failures in the United States have been reported since HDCV was licensed in 1980. Of 13 cases of postexposure treatment failure that occurred outside the United States, all were from not cleaning wounds, not giving rabies vaccine, or giving rabies vaccine into the gluteal rather than deltoid region.
• Prophylaxis before exposure is recommended for persons whose occupations or environments put them at risk, such as veterinarians, animal handlers, laboratory workers where live rabies is common, travelers where medical care is difficult to find or where rabies is common in dogs. Preexposure prophylaxis consists of intramuscular vaccine with HDCV in the deltoid on days 0, 7, and 21 or 28. Note that preexposure prophylaxis obviates the need for postexposure rabies immune globulin but not postexposure vaccine. This can be a significant advantage to the traveler when human (versus equine) rabies immune globulin is unavailable.

Consultations

Consultations with infectious diseases specialists, critical care specialists, neurologists, and the CDC are appropriate.

Medication

Rabies immunoprophylaxis requires passive and active immunization.

Rabies immune globulin

Rabies immune globulin is used together with rabies vaccine in previously unvaccinated individuals to provide maximum coverage before an immune response to vaccine occurs.

Human rabies immune globulin (HRIG, Hyperab, Imogam)

Provides passive protection to individuals exposed to rabies virus. Administer one half of dose into and around bite (given anatomic constraints), and administer the remainder IM at a site remote from vaccine administration area.

Rabies vaccine

Rabies vaccine is available as RabAvert and Imovax.

Rabies vaccine (RabAvert)

Inactivated form of virus grown in primary cultures of chicken fibroblasts; offers active immunity and, when used in combination with HRIG and local wound treatment, protects postexposure patients of all age groups; also used for preexposure immunization in primary series and booster dose.
Fourteen days after initiating immunization series, antirabies antibody titers reach levels well above minimal protective level of 0.5 IU/mL.
Must be injected IM and never SC, ID, or IV. Inject into deltoid muscle area in adults, and administer into anterolateral zone of thigh in children.

Human diploid cell vaccine (HDCV, Imovax Rabies Vaccine ID, Imovax Rabies Vaccine)

Inactivated forms of virus that promote immunity by inducing an active immune response. Imovax rabies vaccine ID is for preexposure use only by the intradermal route.

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