Japanese encephalitis

Treatment Overview

Japanese encephalitis is an acute encephalitis caused by the Japanese encephalitis virus, primarily transmitted through mosquito bites. Currently, there are no specific antiviral drugs; treatment mainly involves vaccination as the primary preventive measure, supplemented by supportive therapy. Vaccination effectively stimulates the immune system to produce antibodies, reducing the risk of infection and severe disease.

Therapeutic strategies are divided into active immunity and symptom management. Active immunity centers on vaccination, while symptom management includes fever reduction, control of cerebral edema, and respiratory support. Early diagnosis and vaccination are key to controlling outbreaks.

Types and Mechanisms of Treatment

Japanese encephalitis vaccines are mainly divided into "Inactivated vaccines" and "Live attenuated vaccines." Inactivated vaccines contain killed virus components and require multiple doses to elicit sufficient immunity; live attenuated vaccines use weakened virus strains, inducing stronger immune memory. Both types stimulate B cells to produce neutralizing antibodies, blocking the virus from invading nerve cells.

Supportive treatment mechanisms include: 1) Managing high fever with antipyretics and physical cooling; 2) Treating cerebral edema with diuretics and corticosteroids; 3) Using ventilators during respiratory failure to maintain ventilation. These treatments do not directly eliminate the virus but can improve patient survival rates.

Indications

The vaccine is suitable for populations who have not been infected with Japanese encephalitis and are at risk of infection, including:

• Residents or long-term visitors in endemic areas (such as Taiwan, rural Southeast Asia)
• Individuals engaged in outdoor activities or agricultural work
• Travelers to endemic regions for more than 14 days
• Immunocompromised patients who have not been vaccinated

Symptomatic treatment applies to patients who have already developed symptoms, especially for severe complications such as seizures and altered consciousness, requiring immediate medical evaluation.

Usage and Dosage

Inactivated vaccine vaccination schedule:

• Basic immunization requires 3 doses: the first dose, followed by the second dose 7-10 days later, and a booster dose after 1 year
• Suitable for adults and children over 2 years old, administered via intramuscular injection in the upper arm

Live attenuated vaccines require only 2 doses, spaced 7-28 days apart, suitable for children over 12 months old. Dosage should be adjusted according to age and must follow medical advice.

Benefits and Advantages

The main benefits of vaccination include:

• Reducing infection risk by over 90%
• Establishing herd immunity to block virus transmission
• Significantly decreasing severe neurological sequelae

Advantages of supportive therapy include:

• Alleviating acute symptoms to maintain vital signs
• Reducing mortality from complications such as cerebral edema
• Improving neurological recovery during convalescence

Risks and Side Effects

Common side effects of vaccination include:

• Redness and pain at the injection site (approximately 10-15%)
• Fever and fatigue (5-10%)

Serious allergic reactions (such as anaphylactic shock) occur in less than 1 in 100,000 doses. Risks associated with symptom management medications include:

• Corticosteroids may suppress immune function
• Intubation may lead to secondary infections

Precautions and Contraindications

Contraindications include:

• Severe allergy to vaccine components (such as egg proteins)
• Fever or acute illness at the time of vaccination

Precautions include:

• Monitoring for 30 minutes post-vaccination to manage acute allergic reactions
• Assessing vaccination timing in immunocompromised patients
• Pregnant women are generally advised to postpone vaccination

Interactions with Other Treatments

Recommendations for spacing between vaccines:

• At least 4 weeks between measles vaccine and Japanese encephalitis vaccine
• Can be administered simultaneously with tetanus vaccine at different sites

Drug interactions with symptom treatments include:

• Corticosteroids and anticonvulsants may reduce immune response
• Diuretics and intracranial pressure-lowering drugs require electrolyte monitoring

Effectiveness and Evidence

Protection after third-generation inactivated vaccine reaches 80-90% after completing the primary series, with booster doses extending protection for several years. Large epidemiological studies show a 70-90% reduction in infection rates in vaccinated areas.

Clinical evidence for supportive therapy indicates:

• Timely cooling reduces the risk of brain injury
• Respiratory support can decrease mortality in severe cases from 30% to below 15%

Alternatives

Currently, there are no alternative vaccines to Japanese encephalitis vaccine. However, the following protective measures can be combined:

• Using insect repellent and wearing long-sleeved clothing
• Environmental control to eliminate mosquito breeding sites
• Isolating infection sources to break transmission chains

Alternative symptom relief options include:

• Using non-steroidal anti-inflammatory drugs to control cerebral edema
• Using neuroprotective agents to reduce brain tissue damage

 

Frequently Asked Questions

What daily life adjustments should patients pay attention to during Japanese encephalitis treatment?

During treatment, avoid strenuous exercise and overexertion, and maintain regular sleep patterns to promote immune recovery. Dietary recommendations include high-protein, vitamin-rich foods such as fish and dark vegetables, while avoiding cold or spicy foods. If headaches or consciousness disturbances occur, reduce activities to prevent falls.

Is antiviral medication still necessary after receiving the Japanese encephalitis vaccine?

The vaccine significantly reduces infection risk, but if diagnosed with Japanese encephalitis, antiviral drugs or other supportive treatments should be administered based on medical evaluation. The vaccine is mainly preventive; treatment after diagnosis depends on disease stage (acute or sequelae) and requires personalized planning.

What should be done if high fever persists during Japanese encephalitis treatment?

Fever is a common symptom; physicians may prescribe antipyretics (such as acetaminophen) and monitor neurological symptoms. If fever exceeds 39.5°C or is accompanied by seizures, seek immediate medical attention for medication adjustment. At home, measure temperature every 4 hours and keep the environment cool and ventilated.

How long after recovery from Japanese encephalitis should neurological follow-up be conducted?

It is recommended to perform brain MRI or EEG within 3 to 6 months post-recovery to assess brain lesion recovery. If consciousness disturbances or paralysis occurred during treatment, follow-up may extend to 1 year to monitor potential motor or cognitive sequelae.

What are the possible side effects of immunoglobulin therapy?

Intravenous immunoglobulin may cause localized swelling or fever reactions, usually resolving within 24 hours. If difficulty breathing, skin rash, or palpitations occur, stop the infusion immediately and notify medical staff. Prior allergy history should be disclosed to avoid severe allergic reactions.