RABIES: ITS HISTORY, MYTHS AND TRUTHS

Dr. Priyanka Konwar1, Dr. Monuj Kr. Gohain2, Dr Mridusmrita Buragohain3 & Dr Anjan Jyoti Nath4

    Rabies is a zoonotic viral disease (a disease that is transmitted to human from animals) and is caused by lyssa virus of family rhabdoviridae. The disease infects domestic and wild animals and spreads to people through close contact with infected saliva via bites or scratches. More than 95% of human rabies cases are due to dog bites and the rest associated with cat, fox and other carnivores.

    Despite being a highly fatal disease, which might have threatened the survival of the host species, rabies virus has been able to survive throughout history because of some limiting factors, i.e. difficult transmission (limited to bite, not always efficient) and a long incubation period. The infection of man may be considered an accident in the life cycle of the virus as man is a dead-end host for rabies.

    Homer (9th Century BC) seems to refer to rabies when, in Iliad, Hector insults Teucros and calls him a ‘rabid dog’. Plautus (11 BC) writes in Menaechni (scene V) ‘He stated his wife was rabid like a dog’. The disease is also cited in the Bible (Chapter 13). Dog rabies was known long before human rabies (credible reports of canine rabies date back to 900 BC, whereas rabies in man was first described only in 377 BC). Democritus (5th Century BC) defines rabies in dogs as an ‘inflammation of nerves’ and does not mention human rabies. Also Xenophon (385 BC) describes only canine rabies in Anabasis.

    Hydrophobia remained the main sign and the others were not taken into consideration. The seriousness of the disease in the dog was known, and Columella said it is ‘almost invariably fatal’. The first vague parasitic theory comes from Pliny; he calls rabies ‘lyssa’, a Greek word which means ‘rage’, ‘fury’, ‘frenzy’, but also ‘worm’. The ancient Greeks called rabies “lyssa” (violence). Today, the virus causing rabies is classified in the genus Lyssa Virus”.

    In ancient times prevention and treatment of rabies were based on measures consistent with the culture of that period. Many internal and external substances were used to attempt a therapy, such as the excreta of hen, hyena and seal; gentian, sage, rosemary, thyme, aloe and leek; pieces of swallow nests; snake skin boiled in wine with male crayfish etc. It is possible that some of these remedies proved ‘successful’ as a consequence of the low transmissibility of the disease. In the first century A.D., the Roman scholar Celsus correctly suggested that rabies was transmitted by the saliva of the biting animal. He incorrectly suggested a cure for rabies by holding the victim under water. Those that didn’t drown died of rabies. Other barbaric cures for rabies included burning the wounds with a hot poker and a “hair-of-the-dog”. Homeopathic medicine invokes the use of “similars”, i.e. like cures like. Hairs of the rabid dog were laid on the wound or ingested by the patient. The most interesting cure for rabies involved the use of madstones in 18th century America. Madstones are calcified hairballs found in the stomachs of ruminants such as cows, goats and deer. They were thought to have curative powers by drawing the madness out of the bite wound. Madstones were highly prized as more valuable than rubies and were passed down through generations as “family jewels”. Abraham Lincoln is reported to have transported his son, Robert, from Springfield, Illinois to Terre Haute, Indiana for madstone treatment in 1849 after being bitten by a rabid dog. Robert survived.

    The first real treatment for rabies came in the 1880’s. A French chemistry teacher named Louis Pasteur was dabbling with chicken cholera when he noticed that virulent cultures exposed to the elements no longer caused disease. He also noted that chickens given this weakened or “attenuated strain” were immune to inoculation with fresh, virulent cultures. Pasteur next tried an attenuated vaccine against anthrax in cattle. It worked! He then turned his attention to rabies, the scourge of the world. His initial animal studies were very promising, but Pasteur wanted more time to purify his attenuated vaccine before trying it on himself.

    On July 6, 1885, a 9 year old boy named Joseph Meister was mauled by a rabid dog. A local doctor treated the wounds and told the family that the only person who could save Joseph was Louis Pasteur. After much pleading, Pasteur agreed only after consulting with a couple of real doctors who said Joseph was a “dead boy walking”. Joseph received 13 inoculations in 11 days and made a complete recovery. The word leaked out and patients came streaming in the world over. At the time of Pasteur’s death 9 years later, over 20,000 people had been given his post-exposure prophylactic vaccine.

    Mass reduction in dog numbers to control rabies has been applied since ancient times. Pasteur first demonstrated the possibility of vaccinating dogs to prevent rabies infection and possible transmission to humans in 1885. However, this was not routinely practiced until the 1920s, when domestic animal vaccination was developed and became widely used. Even today, once symptoms develop there is no known treatment for rabies. Instead, the current management for someone exposed to rabies is post exposure prophylaxis (PEP). This involves administration of rabies immunoglobulin and vaccine soon after exposure to the virus, followed by a series of injections over 30 days. To date, PEP has a success rate nearing 100% when administered correctly shortly after exposure to the rabies virus. As a result, there are now comparatively few cases of rabies when people have access to adequate medical treatment. 95% of the 55,000 cases of rabies each year occur in Asia and Africa where medical attention after exposure to the virus is often lacking. Sustainable resources for effective dog vaccination are likely to be available through the development of intersectoral financing schemes involving both medical and veterinary sectors. Prevention of animal rabies through dog vaccination, better public awareness, improved access to cost-effective and high-quality human rabies vaccines, and improved local capacity in rabies surveillance and diagnostics are essential for the elimination of human rabies. Generally, elimination of canine rabies is epidemiologically and practically feasible through mass vaccination of domestic dogs which is cost-effective approach to the prevention and elimination of human rabies deaths.

    It is clear that human rabies can be successfully prevented through the use of modern highly potent cell culture rabies vaccines. These vaccines were developed over two decades ago and yet nerve tissue based vaccines are still used by a million peoples every year in Asia and Africa, and most human rabies deaths occur as a result of the lack of post exposure treatment or due to the lack of safe and effective vaccines. Post exposure treatment with highly purified cell culture vaccines has been dramatically reducing the burden of the disease through the use of intradermal regimens, proven to be highly efficacious. Although some countries have replaced nerve tissue based vaccines with intradermal regimens, more lives could be saved if the use of these vaccines expanded. The cost of upgrading nerve tissue based vaccine production facilities in order to produce cell culture rabies vaccines is beyond the financial budget of most developing countries. Therefore, banning the use of nerve tissue based vaccines alone will not solve the problem as this would remove access to the post-exposure treatment (PET) available to many patients unable to afford modern cell culture vaccines. Due to this, nerve tissue based rabies vaccines are still the stronghold of post exposure treatment for low-income countries in Asia and Africa.

    Thus, elimination of human rabies is dependent on the elimination of dog rabies. Although canine rabies has been eliminated from developed countries through registration and vaccination of dogs and responsible dog ownership, infected dogs remain the primary source of human and livestock exposures. Availability of safe and effective vaccine plays a major role in fight against the disease. The awareness among the public should be raised about the epidemiological features of rabies and simple precautions that can protect individual and bring about a reduction in the overall incidence of rabies. Generally, mass vaccination of dogs, proper post exposure management, appropriate surveillance system, and increasing the awareness of the community about the disease needs special attention for control and elimination of the disease. The awareness regarding myths and facts prevailing in society needs special attention which is very much essential to gain a rabies free world.

MYTHS TRUTHS
The public health significance of rabies is related to the number of cases in an area Rabies is of public health importance because of the high mortality rate, which is 100% when people have no natural resistance to rabies. Fortunately, humans have a relatively lower susceptibility to the rabies virus compared with other hosts
Only one rabies virus is known to cause the disease

 

No, because rabies-related viruses belonging to the genus Lyssavirus can all cause rabies-like disease. Rabies-related viruses include Mokola virus, Lagos bat virus and Duvenhage virus in Africa, European bat viruses 1 and 2, and Australian bat lyssavirus
Rabies is only transmitted by the bite of an animal Rabies can be transmitted through a wound or broken skin when in contact with the saliva of a rabid animal, e.g. even when there is saliva on an animal’s claw when it scratches a victim’s skin. Airborne rabies transmission can also occur in rabid bat caves
Human rabies is only transmitted by dogs

 

The dog is the major carrier of rabies in the urban setting. Rarely, rabies virus is transmitted by cats. In the countryside, people are at risk of contracting rabies when in contact with rabid wild animals such as foxes and jackals.  Although extremely rare, it is possible for the rabies virus to be transmitted from rabies-infected livestock, such as cattle, to humans
There are no asymptomatic carriers of rabies A small percentage (5%) of rabies-infected dogs remain asymptomatic carriers. There can also be cases where the rabies virus is present in tonsils and absent in the central nervous system (CNS)
There are no wild hosts of rabies virus except for foxes There are wild animal carriers that can transfer rabies virus from the natural environment to synanthropic (pastoral and agricultural) subecosystems. In addition to foxes, jackals are included in the wild hosts of rabies.
Human rabies is transmitted by stray dogs In general, rabies can be transmitted to humans by unvaccinated stray and also domesticated dogs
Do not worry there will be no rabies if the dog is vaccinated This is true only if the dog has had a booster shot
Rabid dogs seem to have a fear of water Humans infected with rabies have painful muscle spasms when they try to swallow. This leads to a morbid fear of water (hydrophobia).  In contrast, rabid dogs have no sign of hydrophobia but are very sensitive to external stimuli
Only rabid dogs froth at the mouth

 

Not necessarily. Dogs can be affected by two forms of rabies, the furious form and the paralytic form. In the latter form, because of jaw muscle paralysis the dog’s tongue hangs out of its mouth and it experiences excessive salivation. Paralytic rabies occurs in approximately 20% of rabid dog cases. Consequently, in 80% of rabies no sialorrhea is present.

Frothing at the mouth may also be a symptom of conditions that are more common than rabies, such as  canine distemper, coccidiosis, helminthiasis, ticks, etc.

If a dog bites, it means that it is infected by rabies

 

A dog with the furious stage of rabies can act in that manner. Initially, a dog with furious rabies snaps at strangers. As the rabies progresses, the infected dog bites at inanimate objects, such as tires and chairs. If a furious-phase dog escapes, it will run long distances, snapping at any creature that it encounters, before it enters the final paralytic stage and dies.

Even a healthy dog bites but there is always some reason for the biting, i.e. it is normal for a dog to bite a person who steps on its tail or a stranger who pats its head. In contrast, a rabid dog bites for no reason at all

A friendly dog is not infected by rabies

 

During the incubation period of rabies, a dog can act in a friendly or aggressive manner, depending on its character and training

In the early clinical stage of rabies, dog behavior shifts: a previously aggressive dog can behave in a friendly way, whereas a previously sociable dog can react aggressively

Rabies post-exposure shots are very painful This was true in the past, when rabies shots were given by large-circumference needles through the abdominal wall, which is a very tender area. Now, in adults, rabies shots are administered intramuscularly in the deltoid area. In children, shots can also be administered in the anterolateral aspect of thigh
Rabies post-exposure treatment consists only of an injection of human rabies immune globulin (HRIG) Human rabies immune globulin (HRIG) is infiltrated around and into the wounds to achieve passive immunization aimed at neutralizing the rabies virus. HRIG is always followed by the administration of five doses of vaccine (active immunization), with the first dose and any remaining volume of HRIG being injected simultaneously but NEVER administered in the same syringe or at the same anatomical site. If the exposed person has had a rabies pre-exposure vaccine, a two-dose vaccine schedule is recommended, with no HRIG being administered
First aid is not helpful for those who have been bitten or scratched by an animal suspected of having rabies. It is necessary to clean the animal bite wound promptly and thoroughly. The wound and surrounding tissue should be flushed with a strong stream of water and washed well using soap or detergent. Virucidal disinfectant (povidone iodine) should be applied carefully under skin flaps. Then the injured person should visit a doctor’s surgery or an emergency department so that HRIG can be infiltrated around and into the wounds
Any animal that has bitten humans should be killed because of the danger of rabies

 

Any canine or wild host of rabies that has bitten humans or other domestic animals must be kept under quarantine or killed humanely. If kept under quarantine, the suspected rabid animal should be observed for a reasonable period of time. If killed, the intact head of the suspected rabid animal should be submitted for necropsy and examination to check for the presence of rabies virus in the brain tissues
There is a fixed observation period for suspected rabies hosts that have bitten humans or other hosts No, because the observation period of suspected rabies hosts is related to when the virus made it into the saliva during the pre-symptomatic phase. Thus it depends on the species of rabies animal host. Canine hosts excrete the virus in their saliva 3-14 days prior to the appearance of symptoms, depending on the infectious dose and viral strain.  Consequently, an observation period of up to 2 week for suspected rabid dogs could be recommended
Rabies vaccines are only injectable

 

There are also oral rabies vaccines. In rabies enzoonotic areas, vaccines are incorporated into edible baits to vaccinate dogs and wild hosts such as foxes and jackals

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Authors’ Address: 1*Department of Animal Nutrition, 3Department of Pathology, 4Departmetn of Microbiology, Lakhimpur College of Veterinary Science, AAU, Joyhing, North Lakhimpur, 787 051. *Corresponding Author¨Email: priyankavet2009@gmail.com


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