Colorado Travel Health

RABIES IN INDIA

Written by Roxanne Royce from Colorado Travel Health www.coloradotravelhealth.com.
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Incidence in India

Since 1985, India reports 17.4 per 1000 population bitten yearly with 25,000-30,000 deaths (~ every 2 seconds a person is bitten and ~ every 30 minutes someone dies). An estimated 38 million is lost annually from lost workdays and ~ 25 million for treatment costs. However, rabies is not a notifiable disease in India (it is not required to be reported) and there is no organized surveillance system so accuracy in case counts and deaths is uncertain. (In 2004, for example, the World Health Organization collaborated with the Association for Prevention and Control of Rabies in India and estimated instead 20,565 deaths annually).

Infectious Agent

Rabies is a virus which is neurotropic (infects nerve cells) leading to a fatal encephalomyelitis (inflammation of the brain and spinal cord).

Mode of Transmission

Typically, an animal bite transmits the virus, but very rarely exposure by inoculation of the virus into an existing wound or mucous membrane can occur. In India most of the bites (91.5%) are dog bites (60% strays and 40% pets). Other carnivores and bats are also reservoirs (long-term hosts of disease) and all mammals are, otherwise, considered to be susceptible.

Pathophysiology of Rabies

The virus is in one’s saliva and once inoculated into the wound is then taken up by a nerve synapse providing a route up to the brain where it causes a fatal encephalitis. The virus can access the nerve immediately or it can remain in the wound for an extended period of time before it enters a nerve. Areas where there is a density of nerve endings such as the hands and face usually provide the virus with a much quicker access to the nervous system. Preventing the virus from entering a peripheral nerve, however, can be achieved by cleaning and disinfecting the bite; injecting antibodies into the site and administration of a series of rabies vaccines.

Occurrence

Rabies exists on every continent except Antarctica. Although canine rabies has been eradicated in the United States, it remains highly endemic in some areas of the world such as parts of Africa, Asia, Central and South America.

Risk for Travelers

The rate of exposure to rabies for travelers is probably in a range between 16 and 200 per 100,000. Travelers to endemic countries can try and ascertain one’s risk from the local health authorities of the respective country, the embassy or the consulate office in the United States. In general, street dogs followed by monkeys are the biggest threats. Keeping a distance to animals; not startling them and if charged, picking up a rock (or pretending to do so) can often scare off the animal. Those who frequent caves should know that the bite of a bat can be indiscernible and those with possible monkey exposures should be aware that the animal might jump on one’s back if carrying a backpack with food inside.

Clinical Presentation

The incubation period of rabies is highly variable, can be as short as 72 hours and as long as 3 months. Symptoms are initially nonspecific and then progresses to paresis (partial motor paralysis) or paralysis; muscle spasms in the throat (triggered by an intense hydrophobia); convulsions and delirium can also develop and shortly thereafter coma and death.

Diagnosis

Lab tests; corneal impressions; or a nuchal biopsy can prove the diagnosis.

Treatment

Only one documented case of surviving rabies (once symptomatic) has been recorded. Once symptomatic, there is no effective treatment.

Preventive Measures for Travelers

One should avoid startling animals and eating or transporting food when near monkeys. Avoidance, in general, of mammals - mainly dogs, monkeys, bats and cats can prevent possible exposure (in theory one can be inoculated with the virus by a lick from an animal into a fresh wound or mucus membrane).

Pre-Exposure Vaccination

A series of 3 vaccines on a fixed schedule is given prophalactically prior to one’s travels.

Post-exposure Vaccination

In someone who did not receive a pre-exposure immunization series, they will need to have rabies immunoglobulin (antibodies) injected into the wound site followed by a series of 4 vaccines over a 2-week period.

If someone has received the full pre-exposure vaccination series and then has a possible rabies exposure, 2 doses of a rabies vaccine are still given on days 0 and 3.

Management of a Possible Rabies Exposure

Any animal bite or scratch should be thoroughly cleansed with generous amounts of soap and water and povidone iodine. Suturing should be delayed until rabies immunoglobulin is injected. Human rabies immunoglobulin (HRIG) is preferred over equine rabies immune globulin (ERIG) or purified fractions of ERIG, but if no other option exists should still be administered. A series of vaccines is then administered over a 2-week period of time.

References

CDC. Poliomyelitis. [Cited 2010 April 30]. Available from: http://wwwnc.cdc.gov/travel/yellowbook/2010/chapter-2/rabies.aspx

Written by Roxanne Royce from Colorado Travel Health www.coloradotravelhealth.com. You should follow me on twitter