Rabies

While rabies has been successfully eradicated in many countries, it continues to persist in several Southeast Asian countries, particularly India. In India, a person is bitten by an animal approximately in every 2 seconds, and one person dies of rabies in every 30 minutes. Over 90% of animal bites in India are caused by dogs, with about 60 % of these being stray dogs. Rabies has become endemic in India, with the lower income groups being most vulnerable to the disease.

What is rabies?

Rabies is a virus which can be contracted through the bite or scratch of an infected animal. Most often, it is transmitted through the saliva of an infected animal. The most common carriers of rabies are dogs, both pet and stray, followed by bats, racoons, coyotes, skunks, and foxes.

The rabies virus, once in the body, causes swelling in the brain, which is almost always followed by coma, and eventual death of the infected person. Hence, if not treated early, rabies can be fatal. Unfortunately, by the time symptoms of rabies start to appear, it is almost always too late to treat.

Rabies is a virus transmitted from a rabid animal to a human being. Rabies can manifest in one of two forms. Each of these forms is significantly different from the other.

• Furious Rabies
  Those who are infected with furious rabies develop symptom patterns similar to what the name suggests. The infected people become highly excitable, show hyperactive behaviour and have a volatile temperament. Typical patterns of behaviour observed in furious rabies include fear of water, difficulty breathing, and trouble swallowing. Other symptoms include anxiety, insomnia, hallucinations, confusion, and agitation.
• Paralytic rabies
  The symptoms in this form of rabies do not appear as quickly as those of furious rabies. Over time, those infected with paralytic rabies develop paralysis of the body and slip into a coma before finally succumbing to the disease. The World Health Organization (WHO) reports that paralytic rabies constitutes 30% of all cases of rabies.

Based on the nature and severity of the symptoms that develop in an infected person, rabies is classified into the following stages:

• Incubation
  The incubation period comprises the initial few weeks after the virus has entered the body. During this period, though the virus has entered the body, there are no obvious symptoms. The incubation period can be of varying duration in different people. In some, it can last for a short time period (as little as 5 days), whereas in others it may last as long as 12 weeks.
• Prodromal
  The second stage lasts for 3 to 10 days. This is the stage when the early signs and symptoms of the infection start to develop. However, these early symptoms are largely generalised and can be easily confused with any another simple illness, or they could be simply ignored.
• Acute neurologic period
  This is the stage when the most tell-tale signs of rabies infection start to manifest, and the disease is at its worst. At this stage, pronounced symptoms specific to this disease start to show as a result of severe impairment of the nervous system.
• Final stage
  In this stage, the person usually goes into a coma and dies.

Rabies is a progressive disease, which means that as the disease advances, the symptoms become severe. Symptoms of rabies vary depending on the length of time the person has been infected with the virus. It may take anywhere between 30 to 60 days for the symptoms of rabies to develop. The symptoms in the different stages of rabies infection are as follows:

• Incubation
  In the initial days following infection, there may be some sensation or pain in the area surrounding the wound. This, along with some discomfort like itching may be the first signals of the disease, which are usually not taken too seriously.
• Prodromal
  In time there may be some signs of nausea, chills, cold, and fever. It is common to feel muscle pain and a sense of irritability, along with other symptoms in this stage. These signs are often misinterpreted as ordinary viral infections or simple cases of flu.
• Acute neurologic period
  Over a period of time, the symptoms become very acute, causing very high fever, disorientation, and even aggression. Seizures, in this stage, are also common. Twitches, partial paralysis, fear of light, rapid breathing (hyperventilation), and drooling (hypersalivation) are some other symptoms which may be observed.
• Final stage
  Rabies-infected people may experience anxiety and panic attacks when exposed to water. This is a condition commonly known as hydrophobia or fear of water. In this stage, as all vital organs are slowly compromised, the infected person requires respiratory support and medication to stay alive. Eventually, the person goes into a coma and muscular movement is restricted with hampered breathing. This is a short-lived phase and death usually follows in a few days.

Causes

The rabies virus is the lone cause of the disease. It is transmitted from a rabies-infected animal to another animal or humans. Usually, the virus is present in the saliva of the infected animal, hence, is mainly transmitted by saliva. While it is believed that mammals usually are responsible for the spread of rabies, not all mammals are known to be potential hosts of the disease.

Rabies is most commonly caused when the disease-carrying animal bites a human. However, it can also occur when the infected animal scratches a human, although, the chances are significantly lower. The rabies virus is also known to enter through open wounds when a rabid animal licks these wounds or its saliva comes in contact with them.

Once the rabies virus has penetrated the body, it may attack the body by:

• Travelling straight to the brain through the nervous system; or
• Residing and multiply in the muscle tissue, where it stays protected from the body’s immune system. Following multiplication, it slowly enters the nervous system.

Risks factors

There are several factors which may not necessarily cause rabies but can place a person at a much higher risk of contracting the virus. Here are some of the factors that increase your risk of contracting :

• Living, working or frequenting an area where there are either bats or animals who have rabies.
• Travelling to developing countries, especially Southeast Asia.
• Living in remote areas where there are more wild animals and lower access to medical aid.
• Going on wildlife trails, exploring caves where bats live or camping extensively without any protection against wildlife.
• Working with rabies virus in laboratories.
• Children are at a greater risk of contracting rabies as a majority of the population infected with rabies are under the age of 15.

Several measures can be taken to prevent the incidence of rabies. These measures are as follows:

• Ensuring vaccination of all domestic animals.
• Notifying authorities when there is any animal in the vicinity who is suspected of having rabies.
• Keeping away from wild animals, no matter how docile they may appear.
• Wearing gloves and protective material when in contact with wild/unfamiliar animals.
• Keeping surroundings clean and free of garbage.
• Seeking information and taking adequate precautionary measures before traveling to another country.

Diagnosis of rabies is more difficult right after a person has been bitten as there are no immediate symptoms of the disease. It takes a while for the disease to start manifesting itself. However, early detection is most important in treating rabies effectively.

• Laboratory investigations are usually carried out to check for the rabies virus, but the antibodies against the virus do not usually form until much later. A sample of saliva or biopsy of the skin is also commonly checked for the virus.
• A fluorescent antibody test is another method to diagnose rabies. A skin sample is taken from the back of the neck to test for rabies antibodies. If the virus is present, then the sample will turn the dye fluorescent. Another commonly used test for rabies is a swab test, which is taken from the cornea to check for the presence of the rabies virus.

The course of treatment may vary depending upon when the person was bitten, by which animal, and the appearance of symptoms. The standard procedure for rabies treatment includes:

• A thorough washing and disinfecting of the wounded area using a medicinal soap and water for at least 15 minutes. In case there are any punctures in the skin, they are flushed using soap water. Unless absolutely necessary, it is preferable that the wounds remain unstitched.
• Next, tetanus and/or antibiotic shot is to be administered.
• After the initial management, the person is vaccinated for rabies. If the person has been bitten by a domestic animal and remains asymptomatic (without symptoms), then the doctor may prefer to keep both the person and the animal under careful observation for a few days. In case the domestic animal cannot be observed, a screening test is performed of the person’s neighbourhood to check for the prevalence of rabies. If upon screening, the animal is found to show rabid tendencies, it is euthanized and then examined for rabies thoroughly. In cases where the animal is observed and has not shown any rabid behaviour, no immunization is required.
• If rabies is suspected in the person bitten by the animal, the doctor begins immunization treatment straight away. Rabies antibodies are administered through immunoglobin injections which help fight the disease and prevent the rabies virus from settling in the body. A series of 5 such injections are administered over the course of a fortnight. Some doctors may suggest this round of injections as a precautionary measure, especially in cases where the animal may not be available for observation. In cases where the person is bitten by a wild animal, this is almost always the immediate course of treatment.
• In cases where symptoms have begun to manifest and the patient is beyond the stage of immunization, medication is given to prevent seizures. Muscle relaxants and medicines to relieve anxiety are also prescribed along with painkillers.
• It is important to observe the person carefully throughout the duration of treatment and look for any observable traits that may indicate disease progression. It is important to alert doctors when any such signals are noticed.

Lifestyle management

If diagnosed in time, rabies can be managed and treated effectively so that the infected person lives a completely normal and healthy life. There can be some side effects to rabies treatments which may persist for a while. These side effects can include pain, nausea, stomach upsets, and dizziness. These side effects should get better with time.  However, care should be taken to ensure that the infected person is protected against recurrence. If the exposure to the rabies virus came from lifestyle choices such as some adventure or proximity to wildlife, more precautions must be taken in the future. In the event that the episode occurred in the neighbourhood, all stray animals must be checked and local civic bodies must be alerted.

Prognosis

Although it can be fatal, rabies is a disease which can be cured completely, provided medical care is initiated immediately. The more aggressively and quickly the condition is attended to, the better and more rapid are the chances of making a complete recovery. The longer the delay in administering medical care, the lower are the chances of recovery. However, even if delayed, it is important to administer the rabies vaccines as they have shown to help in certain advanced cases as well.

Complications

There are some complications that can arise due to rabies. However, these complications can be reversed and only persist as long as there is no medical intervention. In terms of the likelihood of the complications to develop, they can be grouped as:

• High likelihood
  Complications that are highly likely to occur include lactic acidosis, respiratory failure, and coma.
• Medium likelihood
  There are some complications which have been experienced by a significant number of rabies-infected population but are not necessarily experienced by all infected individuals. Some of these complications include drooling (hypersalivation), hypotension, swelling in the brain (cerebral oedema), diabetes insipidus, and cardiac arrhythmias.
• Low likelihood
  Some uncommon, yet possible complications that may arise are myocarditis and urinary retention.