The major types of Encephalitis are:

Japanese Encephalitis
Tick-borne Encephalitis
Primary Encephalitis
Secondary Encephalitis

Japanese Encephalitis:

Japanese Encephalitis is a non-communicable disease caused by Flavivirus, transmitted through the bite of the Culex mosquito. Birds are the most common hosts of this form of encephalitis. Here, the vector, the Culex mosquito, acquires the virus from one animal it feeds on and transmits it to the next animal it feeds on. Pigs and horses are the most affected by this.

Many cases of Japanese Encephalitis are seen in India, Cambodia, Vietnam, China, Japan, Indonesia, Myanmar and Nepal.

A person infected with Japanese Encephalitis will show no immediate symptoms. The symptoms usually appear 5-15 days (about 2 weeks) after the onset of the condition and include:

Feeling dazed
Vomiting
Paralysis
High temperature
Disorientation
Vomiting
Stiff neck (Stiffness in the neck is often considered a symptom of meningitis, which can lead to the wrong diagnosis)
Swelling in the testicles
Emotional disbalance
Weakness.

Tick-borne Encephalitis:

Tick-borne encephalitis is a viral infection that affects the central nervous system. It is caused by a virus of the Flaviviridae family. This form of the neurological disorder is majorly classified into:

European tick-borne encephalitis
Siberian tick-borne encephalitis and
Far-eastern tick-borne encephalitis or Russian tick-borne encephalitis

Human beings are often accidental hosts for the Tick-Borne Encephalitis Virus (TBEV) because this virus tends to choose large animals as its host. Humans are most affected in the months that lie between April and November. The transmission of the virus occurs due to the consumption of raw goat’s or cow's milk, or due to the consumption of unprocessed dairy products. Villages and some urban towns in India have reported multiple cases of TBEV.

The incubation period for TBE is 8-14 days (about 2 weeks). In the initial stages, the patient exhibits symptoms including fever, vomiting, nausea and muscle aches. About 20%-30% of these patients experience the second phase of the disease, which affects the central nervous system and is characterised by symptoms such as headache, disorientation, symptoms of meningitis and abnormal motor functions. Some symptoms are temporary, while others might leave a lasting effect, based on the condition.

The European TBEV has a reported mortality rate of 1%-2% while the Far-eastern TBEV has a higher rate of 25%-30%.

Primary encephalitis

Primary encephalitis is when the virus directly affects the brain cells. The infection is either concentrated in one spot or is widespread.

Secondary encephalitis

Secondary encephalitis is a condition when the body’s immune system starts attacking healthy cells of the brain instead of the infected cells. Secondary encephalitis is often seen in the last stages of infection.