Rabies

How is Rabies Spread? 

Rabies is a zoonotic disease caused by the infection of Rabies Lyssavirus (shortly known as the Rabies virus), of the Lyssavirus genus within the Rhabdoviridae family. The virus is transmitted in the saliva of rabid animals (which are infected by rabies), and upon getting bitten or scratched by the animal, the virus-laden saliva enters the human body and gradually ascends to the human brain where it starts to replicate. However, the virus cannot infiltrate the immediate skin. The virus affects the Central Nervous System (CNS), and the infection leads to the inflammation of the brain cells and spinal cord which causes Encephalomyelitis.  

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Rabies Causes

Several lyssaviruses cause rabies including rabies lyssavirus and Australian bat lyssavirus. Warm-blooded species such as humans and other mammals can be infected by the rabies virus. The virus has also adapted to cultivate in cold-blooded vertebrates. Thus most animals can transmit this disease to humans. Rabies infected dogs, cats, monkeys, foxes, wolves threaten a hefty risk to humans. Domestic dogs are the most common reservoir of the rabies virus; more than 90% of human deaths caused by rabies involve dogs in some sort. The mode of transmission of rabies is usually, if not always, by a bite. The virus modifies the behaviour of the host, making it more aggressive than normal to facilitate its transmission to other hosts. However not always the virus is transmitted from animals to humans, transmissions from animals to animals, even from infected humans to humans are theoretically possible, but there are only a handful of cases, and all occurred through organ transplants from infected donors.   

Most Common Rabies Carriers

According to the U.S Centers for Disease Control and Prevention or CDC, bats are the most feared host of the rabies virus. The transmission of the rabies virus from a bat to a human body is also through a bite. In India, rabies is much more prevalent and affects a large number of populations. According to the World Health Organization, the principal rabid animals in India are wild dogs along with other canids. Several species of fox are also well known potential carriers of the rabies virus. Raccoons as the carriers of rabies virus have been in a high rise in the 1990s. Cats, dogs, cows, ferrets, goats, horses, rabbits, beavers, monkeys, woodchucks etc. are some of the well-known carriers of the rabies virus. Here’s a quick graph that you can follow to track the trajectory of the rabies carriers over the years.

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How is Rabies Transmitted in Human Body 

As previously mentioned the rabies virus cannot infiltrate immediate human skin, the infection must have been caused by a bite or a scratch from a rabies-infected mammal. As the virus enters the human body through the virus-laden saliva of the rabid animal, it goes into the tissues and starts to multiply. It gradually travels to the central nervous system via the spinal cord. Finally, it ascends to the human brain and replicates itself, causing severe brain disorder termed as Encephalitis, and the host starts to show severe symptoms. Death can occur if the situation is not handled with urgency. This incubation process lasts around 3-12 weeks.

Rabies Symptoms 

The human body does not display rabies symptoms until the virus has travelled to the brain via the spinal cord. This incubation period takes place within a month, depending on the distance of the exposure point from the brain. Initial rabies symptoms are much like flu, causing weakness, discomfort and severe fever. Rabies symptoms in humans are as follows-Severe fever, headache, drowsiness and stomach pain. 

  1. Rabies causes Swelling of brain cells and spinal cord. 

  2. Develop fear from water. 

  3. Rabies causes Insomnia, anxiety, nausea, hallucination. 

  4. Also rabies causes Muscle cramps, excess secretion of saliva

Rabies Prevention and Rabies Virus Treatment 

The initial rabies prevention methods start at home, from your pet animals, they are prone to get bitten by wild animals when you take them out for an evening walk, none can assure they won’t get into some sort of brawl with other stray animals.

In Pets: 

  1. Always visit a veterinarian on a daily basis. 

  2. Vaccinate your pet against rabies. Keep your dogs and cats indoors. Keep them under strict supervision in this matter. 

  3. Contact the animal control department in case you identify a rabid animal in your neighbourhood. 

In Humans:

  1. Take extreme precaution in your wildlife adventures especially dealing with a wild animal. 

  2. Sincerely clean animal bites and scratches with soap and water. 

  3. Take immediate care if bitten by a rabid animal, vaccinate yourself. 

  4. Keep your pets under supervision and vaccinate them as well. 

Solved Examples

1. Describe Rabies Life Cycle.

After entering the human tissue, rabies virus travels through the central nervous system and ascends to the human brain, which leads to Encephalitis. This incubation process takes place within a month.

2. Rabies Caused by Which Animal?

The mode of transmission of rabies virus is through the virus-laden saliva of rabid animals. The virus can affect all animals, including- dogs, cats, monkeys, bats, woodchucks, coyotes, ferrets etc.

Did You Know?

The actual rabies virus name is Rabies lyssavirus. Over 59000 people die of rabies each year. The most common transmitter of rabies is domestic dogs. The rabies virus symptoms include aversion to water. Preventive measures of rabies include vaccination against the rabies virus, washing wounds and scratches with water and soap. Rabies causes severe headache, nausea, muscle cramps, anxiety, and weakness when the virus reaches the brain.  

FAQ (Frequently Asked Questions)

1. How is Rabies Virus Spread?

The mode of transmission of the rabies virus is through the saliva of a rabid animal which enters the human body after getting a bite or scratch. The virus travels through the spinal cord to the human brain leading to Encephalitis. The incubation period occurs within one month, depending on the distance between the exposure point and the brain. As the virus reaches the human brain, the body starts to show symptoms. Symptoms of rabies in human body include headache, severe fever, aversion to water etc. If not handled with urgency, the situation may lead to death. However, rabies can be cured if handled correctly.  

2. What are the Symptoms of Rabies?

The human body does not display rabies symptoms until the virus has travelled to the brain via the spinal cord. After affecting the tissues of the exposure point the virus reaches the central nervous system (CNS). This incubation period takes place within a month, depending on the distance of the exposure point from the brain. After the incubation period i.e. when the virus reaches the brain , the host starts to display symptoms. Initial rabies symptoms are much like flu, causing weakness, discomfort and severe fever. Rabies symptoms in humans include headache, critical illness, and aversion to water. Rabies can also give rise to hallucination, nausea, muscle cramps, aggressive behavioural changes.