Rabies, a viral zoonotic neglected tropical disease, poses a severe public health threat in over 150 countries and territories, primarily in Asia and Africa. Each year, this disease results in tens of thousands of fatalities, with children under 15 accounting for 40% of these deaths. Rabies infects mammals and is spread to humans and other animals by contact with saliva, most commonly through bites and scratches. Worldwide, nearly all human rabies cases are caused by dog bites and scratches. However, in the United States, bats are now the primary source of human rabies due to the diligent vaccination of dogs against rabies. Rabies immunoglobulin (RIG) is a medication made up of

antibodies An antibody (Ab) or immunoglobulin (Ig) is a large, Y-shaped protein belonging to the immunoglobulin superfamily which is used by the immune system to identify and neutralize antigens such as bacteria and viruses, including those that caus ...

against the

rabies virus Rabies virus (''Lyssavirus rabies'') is a neurotropic virus that causes rabies in animals, including humans. It can cause violence, hydrophobia, and fever. Rabies transmission can also occur through the saliva of animals and less commonly throu ...

. It is used to prevent

rabies Rabies is a viral disease that causes encephalitis in humans and other mammals. It was historically referred to as hydrophobia ("fear of water") because its victims panic when offered liquids to drink. Early symptoms can include fever and abn ...

following exposure. It is given after the wound is cleaned with soap and water or povidone-iodine and is followed by a course of

rabies vaccine The rabies vaccine is a vaccine used to prevent rabies. There are several rabies vaccines available that are both safe and effective. Vaccinations must be administered prior to rabies virus exposure or within the Latent period (epidemiology), l ...

. It is given by injection into the site of the

wound A wound is any disruption of or damage to living tissue, such as skin, mucous membranes, or organs. Wounds can either be the sudden result of direct trauma (mechanical, thermal, chemical), or can develop slowly over time due to underlying diseas ...

and into a muscle. It is not needed in people who have been previously vaccinated against rabies. Common side effects include pain at the site of injection, fever, and headache. Severe allergic reactions such as

anaphylaxis Anaphylaxis (Greek: 'up' + 'guarding') is a serious, potentially fatal allergic reaction and medical emergency that is rapid in onset and requires immediate medical attention regardless of the use of emergency medication on site. It typicall ...

may rarely occur. Use during

pregnancy Pregnancy is the time during which one or more offspring gestation, gestates inside a woman's uterus. A multiple birth, multiple pregnancy involves more than one offspring, such as with twins. Conception (biology), Conception usually occurs ...

is not known to harm the baby. It works by binding to the rabies virus before it can enter

nerve tissue Nervous tissue, also called neural tissue, is the main tissue component of the nervous system. The nervous system regulates and controls body functions and activity. It consists of two parts: the central nervous system (CNS) comprising the brain ...

. After the virus has entered the

central nervous system The central nervous system (CNS) is the part of the nervous system consisting primarily of the brain, spinal cord and retina. The CNS is so named because the brain integrates the received information and coordinates and influences the activity o ...

, rabies immunoglobulin is no longer useful. The use of rabies immunoglobulin in the form of blood serum dates from 1891. Use became common within medicine in the 1950s. It is on the World Health Organization's List of Essential Medicines. Rabies immunoglobulin is expensive and hard to come by in the

developing world A developing country is a sovereign state with a less-developed industrial base and a lower Human Development Index (HDI) relative to developed countries. However, this definition is not universally agreed upon. There is also no clear agreeme ...

. In the United States it is estimated to be more than US$1,000.00 per dose, and around £600 in the United Kingdom. It is made by isolating rabies immunoglobulin from donated

blood plasma Blood plasma is a light Amber (color), amber-colored liquid component of blood in which blood cells are absent, but which contains Blood protein, proteins and other constituents of whole blood in Suspension (chemistry), suspension. It makes up ...

of humans or horses who have high levels of the immunoglobulin. The equine preparation is less expensive but has a higher rate of side effects.

Medical uses

Rabies immunoglobulin (RIG) is indicated for the passive, transient post-exposure prophylaxis of rabies infection, when given immediately after contact with a rabid or possibly rabid animal and in combination with a rabies vaccine.

Post-Exposure Prophylaxis (PEP) Regimen

The administration of Rabies Immunoglobulin (RIG) as part of post-exposure prophylaxis (PEP) depends on whether the individual has been previously vaccinated against rabies. Regardless of immunization status, PEP should begin immediately with thorough wound cleansing using soap and water, or preferably, irrigation with a povidone-iodine solution to reduce the viral load.

Exposure Risk Categories and PEP Indications

According to the World Health Organization, PEP recommendations are based on the severity of exposure: Category I: Touching or feeding animals, or licks on intact skin — No PEP required, only washing of the exposed skin. Category II: Nibbling of uncovered skin, minor scratches, or abrasions without bleeding—Wound washing and immediate vaccination required. Category III: Transdermal bites, deep scratches, mucous membrane contamination with saliva, or any direct contact with bats—Wound washing, immediate vaccination, and administration of rabies immunoglobulin (RIG) or monoclonal antibodies required.

PEP for Non-Immunized Individuals

For individuals who have never received rabies vaccination, PEP consists of both rabies vaccine and RIG. The rabies vaccine should be administered intramuscularly in the deltoid area on days 0, 3, 7, and 14. A fifth dose on day 28 is recommended for individuals with confirmed or suspected immune disorders. A full dose of rabies immunoglobulin (RIG) should be infiltrated around all identified wounds as much as anatomically possible, with any remaining volume administered intramuscularly at a site distant from the rabies vaccine injection.

Mechanism of Action of Rabies Immunoglobulin

Rabies Immune Globulin (RIG) binds to the rabies virus, thereby neutralizing it and preventing its spread to the central nervous system. This provides short-term passive immunity, allowing time for the rabies vaccine to stimulate an adaptive immune response capable of eradicating the virus. RIG is only effective if administered within the first eight days post-exposure, as the host’s immune system typically begins generating its own antibodies one week after exposure. Repeat doses should be avoided, as they may interfere with the body's natural immune response induced by the vaccine.

PEP for Previously Immunized Individuals

For individuals who have been previously vaccinated against rabies, RIG should not be administered. Instead, the rabies vaccine is given intramuscularly in the deltoid area on days 0 and 3.

Society and culture

Names

There are three versions of rabies immunoglobulin licensed and available in the US. Imogam Rabies-HT is produced by Sanofi Pasteur. Kedrab is produced by Kedrion Biopharma. Hyperrab is produced by Grifols. Imogam Rabies-HT and Kedrab have a nominal potency of 150 IU/mL while Hyperrab has a nominal potency of 300 IU/mL and requires smaller dosing. All three versions are used for post-exposure and indicate local infusion at the wound site with additional amount intramuscularly at a site distant from vaccine administration. Kamrab is approved for medical use in Australia.