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What is Rabies Antiserum?
Rabies antiserum, also called rabies immunoglobulin or RIG, is a solution obtained from the blood plasma of animals that have been immunized against rabies. It contains rabies virus neutralizing antibodies that provide immediate short-term passive immunity against rabies.
How Does Rabies Antiserum Work?
Rabies antiserum works by neutralizing the rabies virus at the site of exposure, before it has time to travel through the nervous system to the brain. The rabies virus usually enters the body through a bite or scratch from an infected animal. Once in the body, it travels through the peripheral nerves to the central nervous system. Rabies antiserum, when administered quickly at the exposure site, binds to the rabies virus and prevents it from multiplying and spreading to the nerves and brain. This buys time for the subsequent administration of rabies vaccine to stimulate active immunity in the person.
Post-Exposure Prophylaxis Protocol
The standard post-exposure prophylaxis (PEP) protocol recommended by the World Health Organization (WHO) and various public health agencies consists of both rabies antiserum and rabies vaccine. The key steps are:
– Thorough washing and cleansing of the wound with soap and water to remove any trace of saliva or nervous tissue from the exposed area.
– Infiltration of rabies immunoglobulin around the wound(s) and also at other nearby injection sites within 7 days of exposure. The exact dosage depends on the age and weight of the patient.
– Simultaneous administration of the first dose of rabies vaccine on day 0. Further doses are then given on days 3, 7, 14 and 28 after the first dose.
– RIG should not be administered more than 7 days after the first vaccine dose as it may interfere with active antibody production stimulated by the vaccine.
– Minor scratches or abrasions that have not broken the skin do not normally require RIG or additional vaccine doses beyond the standard post-exposure series.
Importance of Timely Administration
It is absolutely critical to administer rabies antiserum as soon as possible, ideally on the same day as exposure or within 7 days. Delay reduces its ability to prevent viral spread and allows the virus more time to travel through nerves to the CNS. Once symptoms appear, rabies is virtually 100% fatal. Early intervention with RIG can make all the difference between life and death.
Availability and Cost Considerations
While rabies PEP including RIG and vaccine is widely available in developed nations, the high cost can be prohibitive in poorer regions where canine rabies is endemic. A single dose of rabies immunoglobulin commonly costs over $1000. This financial barrier prevents many bite victims from seeking timely and complete post-exposure prophylaxis. Several countries globally are experiencing shortages or stock-outs of RIG due to difficulties in production and distribution challenges. Affordable alternatives, especially for economical regions, are an active area of research.
Alternatives to Traditional RIG
Scientists have investigated alternatives to address the limitations of conventional rabies immunoglobulin derived from non-human mammals. One promising option is high-dose purified equine rabies immunoglobulin (ERIG), which has demonstrated comparable efficacy to traditional RIG in clinical trials. ERIG is more affordable and scalable to produce. Other innovations include development of monoclonal antibody therapies synthesized from hybridomas as well as passive immunization with polyclonal antibody preparations obtained from immunized milk of transgenic animals.
Conclusion
Rabies antiserum or immunoglobulin plays a vital role in post-exposure prophylaxis by providing immediate short-term immunity while the full immune response develops in response to subsequent rabies vaccinations. Prompt administration at or near the exposure site can prevent infection in persons who would otherwise lose their lives without intervention. However, availability and cost remain significant barriers, fueling research into more affordable alternatives. Improving timely access to complete PEP globally is key to eventually eliminating canine-mediated human rabies deaths.
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1. Source: Coherent Market Insights, Public sources, Desk research
2. We have leveraged AI tools to mine information and compile
