CONTROL AND ERADICATION OF RABIES IN INDIA

DR MD MOIN ANSARI

Division of Veterinary Surgery and Radiology

Faculty of Veterinary Science and Animal Husbandry

SKUAST K, Shalimar-190025, J&K, India.

Introduction

Rabiesis a viral zoonotic neuro-invasive disease, caused by a plethora of lyssaviruses, belongs to the order Mononegavirales, viruses with non-segmented, negative-stranded RNA genomes, of which the classical rabies virus is the most important in domestic or wild animals. The arrangement of 5 proteins designated as N, P, M, G, L and the RNA genome determine the structure of the rabies virus.The term is derived from the Latin rabies, “madness”. This, in turn, may be related to the Sanskrit rabhas, “to rage”. The Greeks derived the word lyssa, from lud or “violent”; this root is used in the genus name of the rabies virus, Lyssavirus. In Ancient Greece, rabies was supposed to be caused by Lyssa, the spirit of mad rage.  In the laboratory it has been found that birds can be infected, as well as cell cultures from birds, reptiles and insects.Rabies virus which infects the central nervous system causes acute encephalitis (inflammation in the brain) in all warm-blooded hosts and the outcome is almost always fatal.Once a rabies infection is established, there’s no effective treatment.

Rabies is a preventable viral disease most often transmitted through the bite of a rabid animal. The most common wild reservoirs of rabies are raccoons, skunks, bats, and foxes. Domestic mammals can also get rabies. Cats, cattle, and dogs are the most frequently reported rabid domestic animals. Animals with rabies suffer deterioration of the brain and tend to behave bizarrely and often aggressively, increasing the chances that they will bite another animal or a person and transmit the disease. Most cases of humans contracting the disease from infected animals are in developing nations. Rabies has a long history of association with dogs. The first written record of rabies is in the Codex of Eshnunna (1930 BC), which dictates that the owner of a dog showing symptoms of rabies should take preventive measure against bites. The vast majority of rabies cases reported to the Centers for Disease Control and Prevention each year occur in wild animals. India has the highest rate of human rabies in the world, primarily because of stray dogs, whose number has greatly increased since a 2001 law forbade the killing of dogs. An estimated 20,000 people die every year from rabies in India, more than a third of the global total. Ending human deaths from dog mediated rabies by 2030 will require an active role from India, which has a high concentration of the disease but is also empowered by its rich technical expertise and resources to drive cooperation of other countries in the region.

Stages and Clinical Signs of Rabies:

Three stages of rabies are recognized in dogs and other animals.

1. Prodromal stage:The first stage is prodromal stage which last by 1-3 days period characterized by behavioral changes.
2. Excitative stage:It is this stage that is often known as furious rabies, which lasts 3 to 4 days due to the tendency of the affected animal to be hyper-reactive to external stimuli and bite at anything near.
3. Paralytic or dumb stage:The third stage is the paralytic or dumb stage and is caused by damage to motor neurons. Incoordination is seen due to rear limb paralysis  and drooling and difficulty swallowing is caused by paralysis of facial and throat muscles. This disables the host’s ability to swallow, which causes saliva to pour from the mouth. This causes bites to be the most common way for the infection to spread, as the virus is most concentrated in the throat and cheeks, causing major contamination to saliva. Death is usually caused by respiratory arrest.

Rabies has also occasionally been referred to as Hydrophobia (“fear of water”) throughout its history. It refers to a set of symptoms in the later stages of an infection in which the person has difficulty swallowing, shows panic when presented with liquids to drink, and cannot quench their thirst. Any mammal infected with the virus may demonstrate hydrophobia. Saliva production is greatly increased, and attempts to drink, or even the intention or suggestion of drinking, may cause excruciatingly painful spasms of the muscles in the throat and larynx. Since the infected individual cannot swallow saliva and water, the virus has a much higher chance of being transmitted, since it multiplies and assimilates in the salivary glands and is transmitted through biting. Hydrophobia is commonly associated with furious rabies, which affects 80% of rabies-infected people. The remaining 20% may experience a paralytic form of rabies that is marked by muscle weakness, loss of sensation, and paralysis; this form of rabies does not usually cause fear of water.

In animals the first symptoms of rabies may be nonspecific and include lethargy, fever, vomiting, and anorexia. Signs progress within days to cerebral dysfunction, cranial nerve dysfunction, ataxia, weakness, paralysis, seizures, difficulty breathing, difficulty swallowing, excessive salivation, abnormal behavior, aggression, and/or self-mutilation.In human, first symptoms of rabies may be very similar to those of the flu including general weakness or discomfort, fever, or headache.The rabies virus attacks the central nervous system of the host, and in humans, it can cause a range of debilitating symptoms- including states of anxiety and confusion, partial paralysis, agitation, hallucinations, and, in its final phases, a symptom called “hydrophobia,” or a fear of water. The symptoms eventually progress to delirium, and coma. Death usually occurs 2 to 10 days after first symptoms. In human, the incubation period (the time between initial contact with the virus and onset of the disease) generally ranges from two to eight weeks. In rare cases, it can vary from 10 days to 2 years. The incubation period is shorter in children and in people exposed to a large dose of the rabies virus.

Diagnosis:

Tests are performed on samples of saliva, serum, spinal fluid, and skin biopsies of hair follicles at the nape of the neck. Saliva can be tested by virus isolation or reverse transcription followed by polymerase chain reaction (RT-PCR). Serum and spinal fluid are tested for antibodies to rabies virus. The reference method for diagnosing rabies is the fluorescent antibody test (FAT), an immunohistochemistry procedure, which is recommended by the World Health Organization (WHO).

Differential Diagnosis:

The differential diagnosis in a case of suspected human rabies may initially include any cause of encephalitis, in particular infection with viruses such as herpesviruses, enteroviruses, and arboviruses such as West Nile virus. The most important viruses to rule out are herpes simplex virus type one, varicella zoster virus, and (less commonly) enteroviruses, including coxsackieviruses, echoviruses, polioviruses, and human enteroviruses. Epidemiologic factors, such as season, geographic location, and the patient’s age, travel history, and possible exposure to bites, rodents, and ticks, may help direct the diagnosis.

Control and Eradication of rabies:

Almost all human exposure to rabies was fatal until a vaccine was developed in 1885 by Louis Pasteur and Émile Roux. Their original vaccine was harvested from infected rabbits, from which the virus in the nerve tissue was weakened by allowing it to dry for five to ten days. Similar nerve tissue-derived vaccines are still used in some countries, as they are much cheaper than modern cell culture vaccines. Rabies in humans can be eradicated through ensuring adequate animal vaccination and control, educating those at risk, and enhancing access of those bitten to appropriate medical care. Once a rabies infection is established, there’s no effective treatment. Though a small number of people have survived rabies, the disease usually causes death.

The annual World Rabies Day campaign, first observed in 2007, brings together researchers and partners to accomplish these goals by mobilizing awareness and resources in support of human rabies prevention and animal rabies control around the world including India.Key interventions for rabies control include vaccination for high-risk individuals, surveillance of human cases, post-exposure prophylaxis following animal bites, vaccination and/or culling of the canine population and other animal reservoirs. Almost all of the human deaths attributed to rabies are due to rabies transmitted by dogs in countries where dog vaccination programs are not sufficiently developed to stop the spread of the virus.

Under the One Health Initiative, WHO, OIE, FAO, and GARC are working on simultaneous campaigns to eliminate canine rabies through the vaccination of dogs, the treatment of human rabies exposures with wound washing and post-exposure prophylaxis, and the improvement of education about rabies prevention where it is needed most. Because pet animals can get rabies from wildlife and then could spread it to humans, preventing rabies in pet animals is also an important step (Educate. Vaccinate. Eliminate) in preventing human rabies cases. “The elimination of rabies in India is a daunting task, but not an impossible one,” says DrReeta Mani, Associate Professor of India’s National Institute of Mental Health & Neurosciences (NIMHANS). “Control of canine rabies through vaccination and dog birth control is imperative, although with 25 million stray dogs in the country this is a formidable task.” While the sheer size of India’s dog population is a significant obstacle, Dr. Mani also points out recent positive developments: “Collaborative efforts between the medical, veterinary, and public health sectors have already made a significant difference. We have seen improved rates of pre-exposure vaccination (PrEP) for vulnerable populations, such as children, and improved awareness of the need for post-exposure prophylaxis (PEP) after a bite.” Within recent years, India has overcome polio, yaws, and maternal and neonatal tetanus. Through a collaborative approach it is possible that this generation will also see the end of rabies in India.

1. Washing bite wounds and scratches for 15 minutes with soap and water, povidone iodine, or detergent may reduce the number of viral particles and may be somewhat effective at preventing transmission. It is an effective way of preventing infection, while both pre-exposure and post-exposure vaccinations for humans exist. Global elimination of the disease is feasible through mass vaccinations of dogs, which transmit 95% of rabies cases to humans.
2. Visit your veterinarian with your pet animals on a regular basis and keep rabies vaccinations up-to-date for all cats, ferrets, and dogs.
3. Maintain control of your pets by keeping cats and ferrets indoors and keeping dogs under direct supervision.
4. Spay or neuter your pets to help reduce the number of unwanted pets that may not be properly cared for or vaccinated regularly.
5. Call animal control to remove all stray animals from your neighborhood since these animals may be unvaccinated or ill.
6. Keeping pets up to date on their rabies vaccination will prevent them from acquiring the disease from wildlife, and thereby prevent possible transmission to family or other people.
7. Understanding rabies risk and knowing what to do after contact with animals can save lives.
8. If find an injured animal, don’t touch it; contact local authorities for assistance.
9. If anybody comes into contact with a rabid animal, rabies in humans is 100% preventable through prompt appropriate medical care.
10. If anybody is bitten, scratched, or unsure, contact to a healthcare provider about PEP protocol.
11. PEP consists of a dose of human rabies immune globulin (HRIG) and rabies vaccine given on the day of the rabies exposure, and then a dose of vaccine given again on days 3, 7, and 14. The vaccine should be given at recommended intervals for best results. Rabies prevention is a serious matter and changes should not be made in the schedule of doses.
12. For people who have never been vaccinated against rabies previously PEP should always include administration of both HRIG and rabies vaccine.
13. The combination of HRIG and vaccine is recommended for both bite and non-bite exposures, regardless of the interval between exposure and initiation of treatment.
14. People who have been previously vaccinated or are receiving pre-exposure vaccination (PrEV) for rabies should receive only vaccine.
15. PrEV for those people who work with rabies in laboratory settings and animal control and wildlife officers are just a few of the people who should consider rabies pre- exposure vaccinations.
16. If anybody is traveling to a country where rabies is widespread, you should consult your doctor about the possibility of receiving PrEV against rabies. Although pre-exposure vaccination does not eliminate the need for additional therapy after a rabies exposure, it simplifies management by eliminating the need for rabies immune globulin and decreasing the number of doses of vaccine needed.
17. Pre-exposure prophylaxis may also protect people whose post-exposure therapy is delayed and provide protection to people who are at risk for unapparent exposures to rabies.
18. For primary vaccination, three 1.0 mL injections of HDCV or PCEC vaccine should be administered intramuscularly (deltoid area), one injection per day on days 0, 7, and 21 or 28.
19. For booster doses, people who work (continuous risk) with rabies virus in research laboratories or vaccine production facilities are at the highest risk for unapparent exposures. Such persons should have a serum sample tested for rabies antibody every six months. Intramuscular booster doses of vaccine should be administered to maintain a serum titer corresponding to at least complete neutralization at a 1:5 serum dilution by the rapid fluorescent focus inhibition test (RFFIT).
20. For people who is works as laboratory workers (frequent risk) such as those performing rabies diagnostic testing, veterinarians and staff, and animal-control and wildlife officers in areas where animal rabies is enzootic. Such people should have a serum sample tested for rabies antibody every 2 years; if the titer is less than complete neutralization at a 1:5 serum dilution by the RFFIT, the person also should receive a single booster dose of vaccine.
21. For Veterinarians, veterinary students, and terrestrial animal-control and wildlife officers working in areas where rabies is uncommon to rare (infrequent exposure group) and at-risk international travelers fall into this category and do not routine pre-exposure booster doses of vaccine after completion of primary pre-exposure vaccination.

Prognosis:

Vaccination after exposure, PEP, is highly successful in preventing the disease. In unvaccinated humans, rabies is almost always fatal after neurological symptoms have developed.

CONTROL AND ERADICATION OF RABIES IN INDIA

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