Encephalitis is an inflammation of the brain that is caused by viral, bacterial or other illness, and leads to tremors, convulsions, hallucinations and memory loss. It is not, in itself, a disease but rather a sickly condition brought about by any one of several diseases and health complications.

In some cases, the condition is an indicator of new infection, while in other times it is a reaction to pre-existing illness that has been lying dormant in the body.


What causes encephalitis?

Encephalitis may be caused by any of the following diseases or conditions:

  • Encephalitis caused by viral infection: This is a brain inflammation caused by viral infection, most commonly by rabies, herpes, polio and measles. But it may also be caused by many other viral infections including the jaundice causing class of virus whose signature is the yellowing of skin and the whites of the eyes, as well the class of viruses related to the similarly named but totally different disease called Japanese encephalitis.

    This type of brain inflammation may be a consequence of new infection or may be a reaction to pre-existing illness.

  • Encephalitis caused by bacterial infection: This is the inflammation of the brain that results from diseases caused by bacteria. It is often a result of new meningitis infection or a complication from pre-existing syphilis infection but may also be an indicator of other common bacterial infections such as malaria. This type of brain inflammation tends to more prevalent in people with a weakened immune system.
  • Limbic system encephalitis: This is a type of brain inflammation that is defined not by its cause but by its curious focus on one section of the brain. It attacks the limbic system – the section on the base of the brain responsible for the sense of smell, behavior, motivation and long term memory.
  • Encephalitis caused by faulty immune system: This is the brain inflammation caused by an attack on the brain by the body's own immune system. This unfortunate turn of events usually occurs after antibodies – the proteins produced the body to identify foreign objects for neutralization by the immune system – are confused or misled by viral or other infections into mistaking brain cells for foreign objects. It is one of the scarier and quite devastating strains of Encephalitis.
  • Semi-consciousness causing Encephalitis: This is another unusual type of brain inflammation defined by its effects rather than its cause. First widely observed in a global 1918-30 epidemic, it leaves its survivors in a speechless, motionless, semi-consciousness state that lasts for decades. It is, easily, the scariest of all types of Encephalitis. Fortunately, it is also a very rare strain that is believed, but not yet confirmed, to be caused by a bacterial infection of by a faulty response to infection by the body's immune system.


Because it is not a disease of its own, Encephalitis is not directly preventable. Rather, it is prevented indirectly by the prevention of the diseases and conditions that precipitate it.

This means prevention of the viral and bacterial infections as well as tackling of the other conditions that may lead to its occurrence. In some cases, that might include vaccination or the control of the animal or insect vectors that transmit the particular disease to human beings.


Symptoms of encephalitis vary between adults and young children. In adults, the early symptoms are high fever, headache, and confusion. As the infection worsens, the victim may become drowsy and fatigued before progressing to seizures, tremors, hallucinations and memory loss.

In younger children and infants, the onset of the condition is usually signaled by irritability, poor appetite and fever. The disease then progresses in the same way as in adults.


There is no vaccination specific to Encephalitis because it is not, in itself, a disease. However, there are vaccines for most of the viral diseases that cause the condition, such as rabies, herpes, poliomyelitis and measles. Many bacterial infections also have well established vaccines.


Again because Encephalitis is not a disease but a consequence of other diseases, its treatment is closely dependent on the underlying diseases responsible for its occurrence. In particular, effective treatment depends on correct diagnosis to determine whether the condition is a result of viral, bacterial or immune system problem.

But on instances where the victim is severely sick, standard supportive treatments, such as mechanical ventilation, steroid hormones and sedatives, are recommended.