Japanese encephalitis

Generally, patients suffering from Japanese Encephalitis (JE) do not present with any symptoms; however, if symptoms do occur, they typically appear 5 to 15 days after infection. The symptoms usually progress through the following three stages:

1. Prodromal Stage

• General malaise
• Fever
• Headache
• Vomiting

2. Acute Encephalitic Stage

• High fever (100°–107°F)
• Stiff neck
• Convulsions
• Confusion
• Disorientation
• Unconsciousness
• Coma

3. Late Convalescent Stage

• Fever resolves
• Neurological signs may improve or remain

Japanese encephalitis is caused by a flavivirus, which can affect both humans and animals. Understanding the transmission cycle is crucial to knowing the cause.

Transmission

This virus exists in a zoonotic transmission cycle, meaning infections spread from animals, through insects, to humans. The general carriers and hosts of this virus are:

• Mosquitoes: The major mosquito vectors of JEV vary in different geographic regions. Culicine mosquitoes, primarily the Vishnui group of Culex, are the chief vectors of JE in various parts of India.
• Pigs: Pigs serve as amplifier hosts since they allow the virus to multiply significantly without suffering from the disease, maintaining prolonged high levels of the virus. This enables mosquitoes to become easily infected by pigs.
• Water birds: Birds belonging to the family Ardeidae (such as cattle egrets and pond herons) are important maintenance hosts.
• Humans: Humans are the end hosts in the transmission cycle. Mosquitoes do not become infected from JE patients, and there is no human-to-human transmission of JE.

Note: In most temperate areas of Asia, JEV is transmitted mainly during the warm season. In tropical and subtropical regions, transmission can occur year-round but often intensifies during the rainy season and pre-harvest period in rice-cultivating areas.

• Year-round tropical climates; India is included in the high-risk countries.
• High density of Culex mosquitoes.
• Presence of hosts such as pigs and water birds in large numbers.
• Paddy cultivation in extensive areas.
• Living or working outdoors in high-risk areas.
• Camping or traveling in high-risk areas for extended periods, especially during the rainy season.

The factors determining who among the infected develop the disease are unknown, but the following factors can influence it:

• Age
• Genetic make-up
• General health
• Pre-existing immunity

Individuals who live in or have traveled to a JE-endemic area and experience encephalitis are considered a suspected JE case. Confirming the diagnosis consists of the following:

1. Detailed medical and travel history

   Individuals who have recently traveled to or resided in regions endemic to JE are suspected of infection with JEV.

   JE should be considered in a patient with:

   • Acute onset of fever not more than 7 days duration
   • Change in mental status which may include:
   • New onset of seizures (excluding febrile seizures)
   • Other early clinical findings such as irritability or abnormal behavior greater than usual febrile illness

2. Laboratory tests

   • Cerebrospinal fluid (CSF): It detects JE by testing for specific IgM antibodies, which typically appear 3–8 days after symptom onset.
   • Peripheral smear examination: This test identifies signs of infection such as lymphocytic pleocytosis and elevated white blood cell count, although it is not specific for JE.

3. Serological Tests

   • Plaque Reduction Neutralization Test (PRNT): PRNT is a gold standard for diagnosing flavivirus infections. It confirms JE by detecting a fourfold increase in IgG titers in acute and convalescent sera.
   • Enzyme-Linked Immunosorbent Assay (ELISA): MAC-ELISA is the first-line test for acute JE infections, detecting JE-specific IgM antibodies.
   • Hemagglutination Inhibition (HI) Test: This test measures antibody response to a virus by using hemagglutinin proteins that bind to red blood cells.
   • Indirect Immunofluorescence Assay (IFA): It detects antibodies by their reaction with viral antigens on infected cells, visualized with fluorescently labeled antibodies.
   • Nucleic Acid Amplification (RT-PCR): RT-PCR tests are sensitive and specific for detecting low viral levels in the early phase of infection.
   • Staphylococcal Coagglutination Test: This rapid test uses monoclonal or polyclonal antibodies to detect JE quickly.

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The best way to prevent Japanese encephalitis virus infection is to protect against mosquito bites. Tips that can help prevent it include:

Safeguard Against Mosquitoes

• Use Environmental Protection Agency (EPA) registered insect repellents.
• Reapply insect repellent as directed.
• Do not spray repellent on the skin under clothing.
• Apply sunscreen first and then insect repellent second, if using sunscreen.
• Wear long-sleeved shirts and long pants.
• Use 0.5% permethrin (an insecticide that kills or repels mosquitoes) to treat clothing and gear (such as boots, pants, socks, and tents).
• Use screens on windows and doors and repair holes in screens to keep mosquitoes outdoors.
• Stop mosquitoes from laying eggs in or near water.
• Use air conditioning, if available.
• Empty or throw out items that hold water, such as tires, buckets, planters, toys, pools, birdbaths, flowerpots, or trash containers, once a week.

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Protection For Kids

• Spray insect repellent onto hands and then apply to a child’s face.
• Cover strollers and baby carriers with mosquito netting.
• Do not use products containing oil of lemon eucalyptus (OLE) or para-menthane-diol (PMD) on children under 3 years old.
• Do not apply insect repellent to a child’s hands, eyes, mouth, cuts, or irritated skin.
• Always follow the product label instructions.

Use Mosquito Nets Correctly

• Tuck the net under the mattress to keep mosquitoes out.
• Tuck netting under the crib mattress or select a mosquito net long enough to touch the floor.
• Pull the net tightly to avoid choking hazards for young children.
• Hook or tie the sides of the net to other objects if they are sagging towards the sleeping area.
• Check for holes or tears in the net where mosquitoes can enter.
• Do not sleep directly against the net, as mosquitoes can still bite through holes in the net.

Travel Safe

• While traveling, choose a hotel or lodging with air conditioning or window and door screens.
• Minimize outdoor activities during dawn and dusk in JE endemic areas.
• Utilize improved and safe methods of animal rearing.
• Travelers to rural areas can be vaccinated after consulting a doctor.

Vaccination in India

India has addressed the challenge of Japanese encephalitis through targeted vaccination programs in endemic areas. Recent efforts focus on expanding vaccination coverage among children in these regions, while adult vaccination has been introduced in highly affected states like Assam, West Bengal, and Uttar Pradesh.

Currently, there is no specific treatment for Japanese Encephalitis (JE) that can directly target the virus. Hence, the management is essentially supportive care to relieve symptoms and complications.

Supportive Care

• Medications for Fever and Pain Relief
  • Acetaminophen (paracetamol) may be given to manage fever, headache, or body aches.
  • Nonsteroidal anti-inflammatory drugs (NSAIDs) are usually avoided due to the risk of bleeding complications.
• Fluid Management
  • Adequate hydration is crucial, especially if the patient has high fever, vomiting, or diarrhea.
  • Intravenous (IV) fluids may be administered if required.
• Hospitalization
  • Severe cases often require hospitalization for stabilization, close monitoring, and medical care. This is especially important for patients with severe or neurological complications.

Research is ongoing into various antiviral treatments for JE, but they have yet to be proven effective in clinical settings.

There is no effective and exact treatment for Japanese Encephalitis, but like any other viral infection, mild symptoms can be managed by:

1. Hydrate Yourself

   To stay hydrated, drink plenty of water throughout the day. You can also include water-rich foods like fruits and vegetables in your diet to maintain proper hydration levels.

2. Get Enough Rest

   Rest helps the immune system recover and fight the infection effectively. Ensure you get 7-8 hours of sleep each night and take breaks throughout the day to allow your body to heal.

3. Eat Right

   Eating a balanced diet with fruits like oranges, apples, and berries, and vegetables such as spinach, broccoli, and carrots can boost immunity and aid in recovery during viral fever. These foods provide Vitamin A, Vitamin C, and antioxidants essential for fighting infection and reducing inflammation.

4. Take Supplements

   Multivitamin supplements that contain vitamins and minerals can support the immune system and help in recovery. It's important to consult a doctor for proper dosage and advice.

5. Other Home Remedies
   • Lemon (Nimbu): It is rich in vitamin C, which may support immunity and help the body fight by promoting overall health. How to use it? You can consume lemon water daily by mixing fresh lemon juice with warm water or add lemon to your meals.
   • Honey (Shahad): It has antimicrobial and anti-inflammatory properties, which can help support the immune system and fight infections along with relieving symptoms. How to use it? Take a spoonful directly or mix it with warm water or tea.
   • Holy basil (Tulsi): Known for its antiviral, anti-inflammatory, and immune-boosting properties, which may help in reducing symptoms. How to use it? Boil a few tulsi leaves in water and drink it as tea, or chew fresh leaves.

Some of the common complications include:

• Seizures: JE is associated with seizures in 46% of patients in the acute stage of encephalitis.
• Increased intracranial pressure: This refers to growing pressure inside the skull due to seizures in cases of JE.
• Status epilepticus: A seizure that lasts longer than 5 minutes or involves more than one seizure within 5 minutes, without a return to a normal level of consciousness between episodes.
• Parkinson's-like symptoms: Symptoms such as a mask-like face, rigidity, and tremor. Acute flaccid paralysis can also be a presenting symptom.
• Acute encephalitis: A severe inflammation of the brain that can lead to symptoms like fever, confusion, and neurological impairments.
• Aspiration pneumonia: This occurs when food, saliva, liquids, or vomit are breathed into the lungs or airways instead of being swallowed into the esophagus and stomach, often due to a reduced gag reflex in patients with JE.

Note: Protecting yourself against mosquito bites is the best way to prevent complications from mosquito-borne diseases. Our experts offer practical tips to help you protect yourself effectively.

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