What is rabies?

Rabies is a disease transmitted from animals to humans, which is caused by a virus. There are two clinical manifestations of rabies – frantic and paralytic. Frantic rabies is most common form of human rabies.

How is rabies transmitted?

The rabies virus invades the nervous system of mammals. It is primarily transmitted from the rabid animal’s saliva when it bites or scratches someone. Licks to wounds or grazed and broken skin, or to the lining of the mouth and nose, can also transmit the disease. Dogs are responsible for 96% of human rabies cases in South-East Asia, but there are also reports of human rabies due to bites of cats, mongooses, jackals, foxes, wolves and other carnivorous animals. Rabies due to monkey and rat bites are rare. Horses and donkeys get aggressive and bite ferociously when they are rabid. Cattle and buffaloes do not bite when they are rabid, but precautions should be taken while examining sick animals that are salivating.

How does one treat an animal bite?

If a person is bitten by an animal:

• Wounds should be washed and flushed immediately with soap and water for 10–15 minutes. If soap is not available, flush with water alone. This is the most effective first-aid treatment against rabies.
• Wounds should be cleaned thoroughly with 70% alcohol/ethanol or povidone-iodine, if available.
• As soon as possible, take the person to a healthcare facility for further treatment.

How long does it take for dogs and cats to develop rabies, and how long does a rabid animal survive?

The incubation period ranges from a few days to several months, whereas the duration of illness – until death – varies from 1 to 7 days.

What are the signs and symptoms of rabies in humans?

Human rabies has the following signs and symptoms:

• pain or itching at the site of the bite wound (in 80% of cases)
• fever, malaise, headache lasting for 2–4 days.
• hydrophobia (fear of water)
• intolerance to noise, bright light or air
• fear of impending death
• anger, irritability and depression
• hyperactivity
• at a later stage the mere sight of water may provoke spasms in the neck and throat
• the duration of illness is usually 2–3 days, but might stretch to 5–6 days or more when receiving intensive care support.

How common is rabies in India?

In India the most common transmitting animal is dog, accounting for more than 96% cases. As per the national multicentric rabies survey done in 2003, about 17 million animal bites occur annually out of which 20 000 human rabies deaths occur in India. About 35% of these are in children.

Is there any specific treatment for a rabies patient?

There is no specific treatment once rabies develops. There is almost nothing that can be done apart from keeping the patient comfortable, and free from physical pain and emotional upset.

Is rabies always fatal?

Human rabies caused by the classical rabies virus continues to be almost 100% fatal, with no specific treatment available anywhere in the world.

Is simply observing the biting dog or cat for 10 days without starting treatment justified?

No. In countries where rabies is prevalent in a large population of dogs and cats, it is compulsory to start treatment and keep the biting dog/cat under 10 days of observation. If the animal remains healthy during the observation period then post-exposure prophylaxis (PEP) can be converted into pre-exposure regimen, i.e. the vaccine taken will be to prevent rabies if bitten in the future.

Under what conditions do we have to take anti-rabies vaccination after being bitten?

Post-exposure rabies prophylaxis (PEP) is compulsory if you are bitten by a dog, cat or other animal that is rabid or is suspected to be infected with rabies.

Do you have to take vaccination against rabies if a vaccinated dog bites you?

No, not if the dog is properly vaccinated against rabies and the efficacy of the vaccine is confirmed by laboratory evidence. Otherwise an appropriate post-exposure prophylaxis (PEP) should be given.

Is there a single-dose human rabies vaccine which will provide life-long immunity?

No. There is no single-dose rabies vaccine available anywhere in the world which can provide lifelong immunity. Single-dose vaccines are available, but they only provide immunity for a limited period of time.

What type of rabies vaccines are available in India?

Rabies vaccines in use can be categorized on the basis of their origin, as follows:

• tissue culture origin
• embryonated egg origin.

Modern rabies vaccines are commercially available as human diploid cell vaccine (HDCV), purified Vero cell rabies vaccine (PVRV), purified chick-embryo cell vaccine (PCECV) and purified duck embryo vaccine (PDEV).

What are the comparative advantages of using the modern rabies vaccines?

Modern rabies vaccines are highly potent, safer to use and provide immunity for a longer period of time – which is important, considering the long incubation period of rabies infection.

What is the exact Schedule of vaccination of anti-rabies vaccines?

The standard schedule is five doses on days 0, 3, 7, 14 and 30, with day '0' being the day of commencement of vaccination. A regimen of 5 one-mL doses of rabies vaccines should be administered IM to previously unvaccinated persons. The first dose of the 5-dose course should be administered as soon as possible after exposure. This date is then considered day 0 of the post exposure prophylaxis series. Additional doses should then be administered on days 3, 7, 14, and 28 after the first vaccination.

Sources:

• FAQs on Rabies. Available from: www.who.int
• IAP Guidebook on Immunization 2013-14. Available from: www.iapindia.org