Japanese Encephalitis: Symptoms, Diagnosis and Treatment

By Visela L. Sangtam

Japanese encephalitis, which is currently prevalent in Nagaland, is a mosquito-borne viral infection caused by the Japanese encephalitis virus which affects both humans and animals. It affects the central nervous system (CNS) and cause severe complications, and even death.

Host: Human, bird, cattle, goat, horse, pig, wild bird

Transmission: Bite by infected mosquitoes — culex tritaeniorhynchus and culex vishnui. Pig acts as amplifier host, as mosquitoes feed on cattle and wild birds infected with JE virus. The infected mosquitoes, then, transfer the amplified virus to humans and animals. Transmission is usually seasonal.

Signs and Symptoms

JE disease manifestations can be divided into three stages in human:

• Prodromal stage- usually lasts for 1-6 days and symptoms include fever, headache, nausea and vomiting.

• Acute encephalitic stage- it begins by the third to fifth day after infection. The symptoms include convulsions, unconsciousness, stiff neck, muscular rigidity, opisthotonos, tremors in fingers, tongue, eyelids and eyes, abnormal movements of limbs and speech impairment

• Late stage- the persistence of signs of CNS injury such as mental impairment, epilepsy, abnormal movements, behaviour abnormalities, paresis either of the upper or lower motor neuron type, increased deep tendon reflexes.

Diagnosis

Culture methods such as Intracerebral innoculation of 1-2 day old mice; use of cell lines such as vero, BHK, and observe cytopathic effect; serological test like virus neutralisation test, indirect FAT, Haemagglutination inhibition; complement fixation test; ELISA-JE-specific IgM capture ELISA; and RT-PCR assay can also be used for identification of JEV in clinical specimens or cell culture fluid using appropriate primers specific for JEV.

Treatment

No specific treatment has been found to benefit the patient with JE. It is symptomatic. However, vaccine is available to prevent the disease. Rest fluid and over the counter pain may relieve some symptoms. Hospitalisation for supportive care and close observation is generally required.

Prevention

• Immunisation with modified live virus vaccine.

• Spraying of insecticides to destroy mosquitoes.

• Use of protective clothing and Apply mosquito repellent or mosquito net.

• Admit the patient to a hospital immediately after the first symptom to reduce the rate of morbidity.