ON June 30, an 18-year-old woman died allegedly due to rabies in Thrissur. The same day, a 60-year-old man also succumbed to the virus. The cases were similar since but one of them died after getting vaccinated.
TNM spoke to doctors to know about the virus, its behaviour, exhibition of symptoms and how to prevent an infection.
Before delving into the details, this is what happened: The woman named Srilakshmi was bitten by her neighbour’s dog on May 30, when she was on her way to college. She took four shots of the anti-rabies vaccine and did not exhibit any symptoms, up until two days before her death.
She was first taken to a private hospital and later admitted to the Thrissur Medical College with high fever, where the doctors stated that she had symptoms of rabies. She passed away on June 30.
The pet dog that bit Srilakshmi had also bitten its owner on May 29, but his condition is said to be stable as of now.
In the case of the sexagenarian named Unnikrishnan Puthukkattil, the dog bite incident happened three months ago. The dog died soon after. He started exhibiting symptoms of rabies a few days ago and was admitted to the same hospital as Srilakshmi, and passed away last night.
However, he was not vaccinated, according to reports.
What is rabies? According to the World Health Organisation, “rabies is a viral zoonotic disease that causes progressive and fatal inflammation of the brain and spinal cord.”
It has two clinical forms: furious rabies, which is characterised by hyperactivity and hallucinations; and paralytic rabies, characterised by paralysis and coma, as specified in the name.
The virus causing the disease is a member of the Lyssavirus genus.
How does rabies spread?
Speaking to TNM, Dr TR Radha, Professor and Head of the Department of Medicine in Thrissur Government Medical College, said the virus may spread to humans through saliva from various groups of animals, including canines, and felines.
“In Western countries, we also have instances of the virus being transmitted from bats,” she said. While household rats pose a lesser threat, chances are there that wild rodents may transmit the virus.
“So as I said, the transmission of virus happens from the saliva of these animals, when they bite, lick, or through breaks in our skin, or oral cavity, that is when we kiss the pets. However, the problem here is that many of these animals are silent carriers of the virus and may not even show symptoms but when they bite a person, the person may get the disease,” she said.
The categories of wound
“Every contact with these animals is categorised depending on the site of the bite, whether it is occurring on intact skin or broken skin, or whether it is in the oral cavity, or parts like neck, face, etc. The closer the site is to the brain the higher the risk of viral transmission to the brain, because basically the disease mainly affects the brain.
"Also, bites on fingers are equally dangerous. From these areas, the virus will retrogradely migrate to the brain,” says Dr Radha.
She further explains that there are three categories of exposure or contact with an animal with the virus. Category I includes touching or feeding animals, or the animal licking on intact skin. Category II includes minor scratches or abrasion in the skin but no blood is drawn. Category III is bites, scratches, saliva entering the broken skin, etc.
“While category I does not necessarily require the patient to get vaccinated, the other two categories must be vaccinated and treated appropriately. And if we don’t know which animal has bitten us, that is if it bites you and runs away, it is always considered as category III exposure, which is the severest form of the bite,” she adds.
What are the symptoms and how long will it take for symptoms to exhibit?
Speaking about the symptoms and the time taken for it to be expressed, especially in these cases where it took from weeks to months to find out about the infection, she says that symptoms can start anywhere between a week to years after a bite. Some reports are there which say that eight years after a bite being forgotten by the patient, they started having symptoms of rabies, she added.
“The symptoms depend on three factors. One is the site of the bite; two, viral load, which is the volume of the virus that went inside our body; and three, the immunity status of the individual. If the person is immunologically compromised, they carry a very high risk of the virus multiplying and producing the disease. So, factors are variable when it comes to producing a disease,” she says.
According to WHO, the incubation period for rabies is stated as two to three months, but may change “from 1 week to 1 year” depending on several factors.
Dr Radha says that the first symptom exhibited is a form of tingling in the wound. Initial symptoms are very non-specific, like fever, body ache, headache, etc, so the people do not even realise that it is rabies.
“The next phase is when we really diagnose the disease, through the classic symptom of hydrophobia (fear of water) and sometimes aerophobia (fear of drafts or of fresh air). When the patient sees water, their throat tightens up and the whole muscles go into spasm. This is the second stage of the disease, which tells us that the disease has already been established. It becomes very difficult to treat at this stage,” she says.
In the last stage of the disease, Dr Radha said the patient goes into an agitated delirium and can develop fits and also altered behaviour. They may try to bite others, they may have foam forming in their mouth.
“So, at this stage, rabies is established, and is considered the terminal stage of the illness. Once it has gone to the established stage, it is 100% fatal. However, there are few cases where the patients have survived after this stage with intensive care and treatment, but none of the survivors was normal. That is, all of them had some form of disability, and most of them were bedridden and they all died later. So, after this stage, survival does not mean normal life,” she says.
How important is vaccination and medical attention?
As for the question of vaccine efficacy, Dr Radha says that there are different types of vaccines available and of late, intradermal vaccination (delivery of vaccines into the outer layers of the skin) is given, which has proved to be 100% efficient.
She also says that there is no question of ‘should we take the vaccine’, because not taking them makes the viral disease fatal.