What are the symptoms of forest encephalitis?

Forest encephalitis is also a common encephalitis. It often occurs in grassland areas and areas with high forest coverage. It is a virus transmitted by ticks. The incidence rate has been relatively high in recent years. It often occurs in people working in the field. When bitten by these small insects, it often leads to high fever, headache, impaired consciousness and other symptoms, which will cause sequelae and have a relatively high mortality rate.

What are the symptoms of forest encephalitis?

1. The incubation period is generally 10 to 15 days, the shortest is 2 days, and the longest is up to 35 days. 2. The prodromal period usually lasts from several hours to 3 days. In some patients and severe patients, the prodromal period is not obvious. The main symptoms of the prodromal phase are low fever, dizziness, fatigue, general malaise, and soreness in the limbs. Most patients have an acute onset of the disease, reaching a peak within 1 to 2 days.

3. Acute phase (1) Fever usually reaches its peak (39.5℃～41℃) 2 to 3 days after onset, lasts for 5 to 10 days in most patients, and then decreases in a step-like manner, returning to normal within 2 to 3 days. The fever type is mostly retained fever, and some patients may experience remittent fever, bimodal fever or irregular fever. (2) Symptoms of systemic poisoning: High fever is accompanied by headache, muscle pain, weakness, lack of appetite, nausea, vomiting, etc. Due to damage to the vasomotor center, the patient may also experience flushing of the face and neck, conjunctival congestion, and slow pulse. Some critically ill patients have symptoms of myocarditis, often with dull heart sounds, increased heart rate, and T wave changes on electrocardiogram. Severe patients may suddenly develop heart failure, acute pulmonary edema, etc. (3) Consciousness disorders and mental damage: More than half of the patients have varying degrees of mental and consciousness changes, such as drowsiness, apathy, confusion, coma, and may also experience delirium and mental confusion.

(4) The most common symptom of meningeal involvement is severe headache, which is often a continuous dull pain in the temporal and occipital regions, sometimes explosive and throbbing, presenting as a tearing headache, accompanied by nausea, vomiting, neck stiffness, and meningeal irritation signs. It usually lasts for 5 to 10 days and may exist at the same time as coma. Once consciousness is restored, it can last for about a week. (5) Muscle paralysis is most common in the form of combined paralysis of the cervical and scapular muscles and upper limbs, with lower limb and facial muscles less common. Paralysis is mostly flaccid, which is different from Japanese encephalitis. It usually appears on the 2nd to 5th day of the disease. Most patients gradually recover after 2 to 3 weeks, but a few have sequelae and experience muscle atrophy, becoming disabled. The disease's unique head drooping symptom occurs due to paralysis of the cervical and scapular muscles. When the scapular muscles are paralyzed, the arms are in a swinging and helpless state. (6) Other manifestations of nervous system damage: Some patients show signs of extrapyramidal system damage, such as tremor and involuntary movements. Occasionally, symptoms of bulbar paralysis such as speech disorders and dysphagia, or mild paresis of the central facial and hypoglossal nerves may be seen. 4. Recovery period: This period lasts an average of 10 to 14 days. The body temperature drops, limb paralysis gradually recovers, consciousness becomes clear, and various symptoms disappear. The general course of forest encephalitis is 14 to 28 days, but a small number of patients may have sequelae such as aphasia, dementia, dysphagia, involuntary movements, and a few patients may have the disease lasting for several months or 1 to 2 years, and patients may show flaccid paralysis, epilepsy and mental disorders. Domestic reports in recent years have shown that the clinical symptoms of patients in the acute phase have been alleviated compared with the past, and the mortality rate has also been significantly reduced, which may be related to the adoption of immunization injections and the strengthening of symptomatic treatment.

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