Mon, Oct 24, 2016 - Page 7 News List

Why rabies still kills 59,000 people a year

By Melvin Sanicas

A virus that infects your brain, makes you want to bite things and is almost always fatal after symptoms appear probably sounds like something from a zombie movie. However, this has been the modus operandi of rabies at least since 2300 BC, when it was described in the Eshuma Code of Babylon. The word’s Sanskrit etymology — rabhas, meaning “to do violence” — dates back even further, to 3000 BC.

In principle, no human in this day and age should die from rabies, and yet, according to a study last year, the virus kills 59,000 people annually. That is 160 people every day and the actual number might be far higher if we could count unreported or untreated cases. Most of these deaths occur in Asia and Africa, with India alone accounting for one-third of the world’s total mortality from rabies.

That total is not as high as the death toll from tuberculosis, HIV/AIDS and malaria; but, unlike those diseases, every mammal appears to be susceptible to rabies. Dogs, the predominant host in most regions, can become infected from any rabid wild animal and then infect humans. Dogs showing symptoms might bite a human, but they can also transmit the virus simply by licking if their saliva comes into contact with a scratch, damaged skin or mucosa.

The rabies virus hijacks the nervous system and actually manipulates neural processes to make its host move faster. Infected humans will eventually hallucinate, become aggressive and even fear water in the advanced stages of the disease.

Once these symptoms appear, rabies has no known cure and death is almost certain. Fortunately, unlike most vaccine-preventable diseases, rabies allows for post-exposure inoculation, because the time of infection is generally known by the victim — especially if they were bitten — and the disease’s incubation period is relatively long, ranging from days to years, but averaging three to eight weeks. Whether administered before or after exposure, the vaccine is the same, but the immunization schedule and the dosage differ between the two scenarios.

French scientist Louis Pasteur formulated the first rabies vaccine in 1885, by injecting the virus into rabbits, waiting for it to kill them and then drying the infected nerve tissues to weaken the virus to the point that it could be safely administered. Then he successfully tested it on a nine-year-old boy who had been bitten by a rabid dog.

In today’s world, Pasteur would be thrown in jail for practicing as an unlicensed physician and not following proper clinical-practice standards, but we can all be thankful for his discovery.

Today, rabies vaccines are grown in a lab using cell cultures. The virus is then rendered inactive, purified and administered by injection into the arm. The WHO recommends pre-exposure vaccinations for anyone whose occupation or residence implies continual, frequent or increased risk of encountering rabies. This applies to everyone in rabies-endemic countries; unfortunately, not everyone in these countries gets vaccinated.

The rabies vaccine is on the WHO List of Essential Medicines and has an average wholesale price of US$11 per dose in the developing world, and as much as US$250 per dose in the US. Of course, because the alternative to post-exposure vaccination is death, the treatment is extremely cost-effective however one looks at it.

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