Encephalitis (Viral Encephalitis)

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What is Encephalitis?

Encephalitis is an inflammation of the brain parenchyma (the functional part of the brain). Patients affected have widespread or focal disability of the neurological and psychological function. Encephalitis is different from meningitis, although, clinically, the 2 often occur together with signs and symptoms of meningitis, such as fear of light, headache, or stiff neck.

Encephalitis usually has a viral cause however, it can occur as a result of bacterial or fungal meningitis.

Common viral causes of encephalitis include Herpes Simplex virus (HSV - most common cause), ECHO, Coxsackie, mumps and Epstein-Barr viruses. A well known case in Australia is the Ross River virus.

Who gets Encephalitis?

The occurence rate encephalitis is about 1 in 200,000 per year. The most commonly affected groups are children, the elderly, and those with suppressed immune system.

Approximately 850 cases of encephalitis were reported in 1994. The true statistics of these infections are difficult to obtain because the diagnosis may not be considered, many cases are unreported, or a specific viral cause is never confirmed.

Predisposing Factors

Exposure to viruses can occur through insect bites, food or drink contamination, inhalation of respiratory droplets from an infected person, skin contact, and extremely rarely, vaccinations.

Progression

Most episodes of encephalitis are mild and patients will recover by themselves. In a small number of cases, the disease can be very serious, leading to brain damage, coma and death.

In general however, the fevers and headaches associated with the illness last for 1-2 weeks before gradually improving. Full recovery may take weeks to months.

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