Most patients do not get rabies immunoglobulin antibody administered at the site of the wound immediately after a dog bite.

Rabies kills nearly 20,000 people in India every year, accounting for a third of global deaths caused due to the disease. The numbers have remained nearly constant for more than a decade, but in all probability are an underestimation of the actual figures as rabies is not a notifiable disease.

“It is an almost 100 per cent fatal disease but also 100 per cent preventable. It’s sad that 20,000 people still die of it every year,” says Prof. Reeta Subramaniam Mani from the Department of Neurovirology, National Institute of Mental Health and Neurosciences (NIMHANS), Bangalore, and a World Health Organisation Collaborating Centre for Reference and Research on Rabies.

Six patients in India have been reported to have survived human rabies in the last six years.Partial protection to blame

One of the main reasons for the large number of avoidable deaths is because a majority of patients do not receive rabies vaccination on time. Even if they do, they most often do not receive all five doses. But most importantly, most do not get rabies immunoglobulin antibody administered at the site of the wound immediately after a dog bite and before vaccination due to near perennial shortage across India.

As a result, many patients tend to be partially protected. Six patients in India have been reported to have survived human rabies in the last six years. Surviving rabies is extremely rare and unheard of until 2010. According to a July 28, 2016 paper in the journal PLOS Neglected Tropical Diseases, till date only 15 human survivors have been reported from across the world. “Sadly, survival has not always been synonymous with recovery” and except in one case in India the rest have had “poor functional outcomes”.

The horse-derived equine rabies immunoglobulin (eRIG) cannot be produced in large quantities as the process is time-consuming; it also has side effects. The human rabies immunoglobulin (hRIG) is safer but is not manufactured in India and is expensive (nearly Rs.20,000).

A human monoclonal antibody

According to an April 2016 paper in the journal Tropical Medicine and International Health, between January 2012 and December 2014, most of the 128 patients with suspected rabies from 11 States did not receive adequate post-exposure prophylaxis.

Against this backdrop, the fast-acting anti-rabies human monoclonal antibody developed by the Pune-based Serum Institute of India will go a long way in preventing hundreds of needless deaths in India each year.

“The government has already issued marketing authorisation to Serum for Rabishield [the rabies human monoclonal antibody]. The Drugs Controller General of India is expected to approve the manufacturing facility next month. Manufacturing will start once this formality is over. Rabishield will be available from the first quarter of next year,” says Dr. Suresh Jadhav, Executive Director at the Serum Institute.

“Shortage of immunoglobulin will be addressed to a great extent [once Rabishield is available]. Doctors are not used to prescribing antibody due to its shortage. But it will definitely pick up and will go a long way in reducing mortality,” he adds.

The cost of Rabishield is expected to be 10-15 per cent of the cost of hRIG.

Vaccination schedule

“Immunoglobulin neutralises the virus that is locally deposited in the wound and prevents the virus from getting into the nerves. When the wound is deep, it is difficult to reach all the parts of the wound. Hence vaccination [at 0-3-7-14-28 days] is needed after the patient is treated with immunoglobulin,” says Prof. Mani. It takes 7-10 days for antibodies to be formed after vaccination, so there is a risk of rabies developing if immunoglobulin is not administered immediately.

But most importantly, if extensive bleeding is present, the bitten area should be immediately washed under running water for about 10-15 minutes before immunoglobulin is administered. Thorough washing alone can remove 50-70 per cent of the virus. “Applying turmeric or slaked lime will irritate the wound and facilitate the entry of the virus into nerves,” she says.

Three doses of vaccine taken prior to dog-bite can prevent rabies. Though one dose costs Rs.300, it drops to Rs.30 per dose when administered intradermally. The drop in price is because only one-tenth of the dose is required when given intradermally for pre-exposure prophylaxis. When given after a dog-bite, one-fifth of the dose is sufficient if administered intradermally. But once opened, a vial should be used within six hours.

Published in The Hindu on August 7, 2016