What are the symptoms of Japanese encephalitis?

The symptoms of type B encephalitis include high fever, impaired consciousness, and convulsions. Especially in the early stages of the disease, patients will have symptoms of a continuous rise in body temperature, as high as 39 to 40 degrees, and will also experience nausea and vomiting.

1. Initial stage

The onset is acute, with body temperature rising sharply to 39-40℃, accompanied by headache, nausea and vomiting. Some patients have drowsiness or mental fatigue and mild neck stiffness. The course of the disease is 1-3 days.

2. Extreme period

The body temperature continues to rise and can reach over 40°C. The initial symptoms gradually worsen, with obvious disturbances in consciousness, ranging from drowsiness and lethargy to coma. The deeper the coma and the longer it lasts, the more serious the condition. Confusion may occur as early as the 1st to 2nd day of the disease, but is more common on the 3rd to 8th day. Severely ill patients may experience whole-body convulsions, tonic spasms or tonic paralysis, and a few may also experience limp paralysis. Severe patients may develop central respiratory failure due to brain parenchymal lesions (especially the brainstem), hypoxia, cerebral edema, brain herniation, intracranial hypertension, hyponatremic encephalopathy and other lesions, which are manifested by irregular respiratory rhythm, double inspiration, sigh-like breathing, apnea, Cheyne-Stokes respiration and mandibular respiration, and finally respiratory arrest. Physical examination may reveal signs of meningeal irritation, slow or absent pupil reaction to light, or dilated pupil, absent abdominal wall and cremaster reflexes, hyperreflexia of deep muscles, and pathological pyramidal tract signs, such as Babinski's sign, which may be positive.

3. Recovery period

After the peak period, the body temperature gradually drops, and the mental and nervous system symptoms improve day by day. Severely ill patients still have dull consciousness, dementia, aphasia, dysphagia, facial paralysis, rigidity or torsion spasm of the limbs, etc. A few patients may also have flaccid paralysis. With active treatment, most symptoms can be recovered within half a year.

4. Sequelae

A small number of severe patients still have mental and neurological symptoms half a year later, which are sequelae, mainly including impaired consciousness, dementia, aphasia, limb paralysis, epilepsy, etc. If they are given active treatment, they can recover to varying degrees. The sequelae of epilepsy can last lifelong.