Japanese Encephalitis: Fever With Confusion

Key takeaways

According to CDC, more than 99% of people infected have no symptoms or only mild ones, and fewer than 1% develop neurological illness. But once the virus has reached the brain, about one in every four people who develop the illness dies.
What you have to react to is not the level of the fever but the HEAD: a fever with ANY change in consciousness or behaviour — confusion, rambling speech, drowsiness that is hard to rouse, an unusual personality change, seizures — means going now.
Young children show it differently from adults: refusing the breast, drowsiness that is hard to rouse, a shrill cry that cannot be soothed, a bulging fontanelle, a body that is floppy or rigidly arched, twitching at the corner of the mouth.
The illness is spread by mosquito bites. According to CDC, the virus is NOT spread directly from person to person by coughing, sneezing or contact — so the patient does not need to be isolated from the family.
According to CDC, there is no specific treatment; treatment is supportive care and usually requires admission to hospital. That is why going early matters more than anything that can be done at home.
Prevention means avoiding mosquito bites — according to CDC the mosquitoes bite both day and night. There is a vaccine against this illness; the schedule and who should have it are matters for a doctor or a vaccination centre.

The most important thing first: with Japanese encephalitis, what you need to react to is not the level of the fever but the HEAD. According to CDC, more than 99% of people infected have no symptoms or only mild ones, and fewer than 1% develop neurological illness — but once the virus has reached the brain, about one in every four people who develop the illness dies. So a fever with any change in consciousness or behaviour means going now.

Recognising it: fevers are common, confusion is not

According to CDC, the illness usually begins with fever, headache and vomiting — like dozens of other things. Then over the following days confusion, weakness and coma appear; seizures are common, especially in children. Also according to CDC, the time from the mosquito bite to the first symptoms is usually five to fifteen days. The things below should be rechecked several times a day.

CONSCIOUSNESS: call them, shake them gently, ask their name, ask what day it is. Being harder to rouse each time than the time before is the most serious sign here.
BEHAVIOUR: rambling or muddled speech, not recognising familiar people, agitation or unusual silence, a personality clearly unlike their ordinary self. Families usually notice this before a doctor does.
SEIZURES: whole-body convulsions, or only twitching at the corner of the mouth, eyes rolling upwards, one arm jerking repeatedly.
STRENGTH AND SPEECH: weakness in one limb, a drooping mouth, difficulty speaking, unsteady walking, unable to hold the head up.
HEADACHE, VOMITING, A STIFF NECK: a severe headache with projectile vomiting, fear of light, a neck that cannot be bent forward. These signs also occur in meningitis; the initial handling is the same — go now and let the doctor tell them apart.

Young children: look at how they feed and how awake they are

Feeding poorly, refusing the breast, vomiting.
Sleeping deeply and hard to rouse; or the opposite, intensely fretful, a shrill cry that does not settle even when picked up.
A bulging fontanelle — the soft spot on top of the head tight or domed.
A body that is floppy when picked up, or rigidly arched. A baby under three months old with a fever goes to hospital, not under observation at home.

What to do straight away

Write down TIMES, not just dates: the time the fever started, the time of vomiting, the time the muddled speech began, the time of a seizure and how long it lasted. The doctor needs to know how many hours this has been going on.
Wake the patient to check on them; do not leave them sleeping “so they can rest” — the level of response is precisely what has to be monitored.
Lay them on their side while they are vomiting, confused, or just out of a seizure, so they do not choke.
For a seizure: ease them to the floor if they are about to fall, put something soft under the head, clear hard objects away, loosen the collar, remove glasses, and time the seizure. Do not put anything in the mouth, do not hold the limbs down, and do NOT give rescue breaths during a seizure. Stay with them until they are fully awake.
Tell the doctor where the patient has recently been, especially rural areas with many mosquitoes, and take the vaccination record with you.

What must NOT be done

Do NOT wait for the fever to come down before deciding: bringing a fever down makes the patient more comfortable but does not slow the illness. Bringing the fever down and going back to sleep until morning is the most dangerous trap in this illness.
Do NOT buy antibiotics yourself: this is a viral illness, antibiotics cannot kill the virus, and taking them before samples are collected also makes the tests harder to read.
Do NOT use coin-rubbing, skin-pricking or cupping; do not make a confused patient drink “detox” remedies.
Do NOT give food or drink while the patient is drowsy or has just had a seizure — it is very easy for it to go into the lungs.
Avoid aspirin in children and teenagers with a viral fever because of its link to Reye syndrome; paracetamol (acetaminophen) is the one usually used, but the dose is a decision for the doctor or the pharmacist.

When you must go to hospital

GO TO EMERGENCY CARE or call 115 (the emergency number in Vietnam) NOW — do not wait until morning — if someone with a fever has ANY of these signs: confusion, rambling speech, not recognising familiar people; drowsiness that is hard to rouse; behaviour or personality markedly unlike their ordinary self; seizures; weakness in one limb, a drooping mouth, difficulty speaking; a severe headache with projectile vomiting, unable to drink anything; fast breathing, difficulty breathing; in a young child: refusing the breast together with drowsiness, a shrill cry that cannot be soothed, a bulging fontanelle, a floppy or rigidly arched body; a baby under three months old with a fever; or anyone with a fever who is clearly deteriorating within a few hours. — BE SEEN THE SAME DAY, do not wait until tomorrow, if: there is a fever with headache and vomiting but no confusion yet; a fever after returning from a rural area with many mosquitoes, rice fields or pig rearing; an older adult or someone with a weakened immune system has a fever with headache. Be seen again within one to three days if you have already been seen and things are still getting worse. — If you are not sure, call and ask before deciding on your own.

Prevention: avoiding mosquito bites, and the vaccine

According to CDC, the best protection is not to be bitten: use insect repellent, wear long sleeves and long trousers, and sleep under a net or in a place with screens on the windows.
According to CDC, the mosquitoes bite both during the day and at night — so do not protect yourself only at bedtime.
According to CDC, transmission occurs mainly in rural agricultural areas, often associated with rice growing and flood irrigation, where the mosquitoes breed near pigs. Visiting the countryside or going out to the fields is when care is needed.
There is a vaccine against this illness. According to CDC, talk to your doctor about whether you or your child needs it; the schedule and who should have it are matters for a doctor or a vaccination centre.

According to CDC, there is no specific treatment; treatment aims to relieve the symptoms, and admission to hospital is usually needed for close monitoring and supportive care. That means this illness can neither be diagnosed nor treated at home. Y Te Xanh's part is two other things — a remote consultation so you can decide whether to go in now, and then nursing care and physiotherapy for recovery at home after discharge. If any sign in the box above is present, go in first and call afterwards.

The signs, the figures and the prevention advice in this article follow publicly available US CDC material; this article passes that on and does not replace being examined. Citing CDC here does not imply that CDC endorses Y Te Xanh or our services.

Need personalised advice for your loved one? Call our hotline 094 368 81 15 (24/7) — calling to ask a question or to book costs nothing. GreenCare has doctors who come to examine, nurses who carry out doctor's orders (injections, infusions, dressing changes), remote consultation by video call, and a review of the medicines you are taking; an in-depth remote consultation, or any one after the first, is a paid service. For children we take examination and acute care only — not long-term care at home, and not newborns or expectant mothers. We confirm we have staff in your area and provide transparent pricing before we begin.

Sources

CDC — About Japanese Encephalitis Virus

Frequently asked questions

Does this spread from person to person — does the patient need to be isolated?

No isolation is needed. According to CDC, the virus spreads when a mosquito bites an infected animal and then bites a person, and it is not spread directly from person to person by coughing, sneezing or contact; it can be spread through blood transfusion or organ transplant. That means caring for the patient will not give it to you, but the whole household still shares the risk if you all live where mosquitoes carrying the virus are — so what needs doing is protecting the whole family from mosquitoes, not separating the patient off.

How does it differ from meningitis, and how would the family know which it is?

The family cannot tell, and does not need to tell before going. Briefly: meningitis is dominated by a severe headache and a stiff neck, while encephalitis is dominated by changes in consciousness and behaviour — confusion, rambling speech, seizures. But the two often occur together, one person can have both, and both need going now. Telling them apart is the doctor's job after an examination and tests, not yours at home.

The fever has lasted a few days but the patient is still alert and talking normally. Is the danger over?

You cannot conclude that yet, but it is an encouraging sign rather than a guarantee. According to CDC, the illness usually begins with fever, headache and vomiting, and confusion and weakness appear only over the following days, so the early stage looks like an ordinary fever. Keep checking the level of alertness several times a day: call them, ask their name, ask what day it is. As long as they are awake and answering correctly, keep watching; if anything shifts, be seen rather than waiting to see more.

If we have had the vaccine, is there still anything to worry about?

Vaccination lowers the risk; it is not an absolute shield, and it does not protect you against the other causes of encephalitis. So treat the vaccine as prevention, and once signs have appeared handle things exactly as if there had been no vaccine: be seen straight away. According to CDC, talk to your doctor about whether you or your child needs it. This article does not give a schedule or a vaccine name, because that is a matter for the doctor and the vaccination centre; when you go to ask, take the old vaccination record with you.

Are there lasting after-effects, and what needs monitoring after discharge?

There can be, and this is the part that takes families by surprise. According to CDC, about one in every four people who develop encephalitis dies, and among the survivors roughly three to five in ten go on to have problems with movement, thinking or behaviour. So after discharge, keep the follow-up appointments, monitor movement and the ability to manage daily tasks, and with a young child monitor development and schooling as well. Rehabilitation started early and done consistently is worth doing, and it can be done at home.