A brain under siege

08 February 2019

Encephalitis may be rare, but when it strikes it can be devastating, and even deadly – especially for children and young people, writes journalist John Windell.

Childs Head iStock

Encephalitis is not a common condition: according to the Encephalitis Society (2017), the UK sees around 6000 cases in a typical year. The global figures are more alarming, with some 4.3 million cases a year leading to 150,000 deaths, indicating just how devastating encephalitis can be (GBD 2015 Disease and Injury Incidence and Prevalence Collaborators, 2016; GBD 2015 Mortality and Causes of Death Collaborators, 2016).

Put simply, encephalitis is an inflammation of the brain. It has a range of triggers, although in most cases the cause is a viral infection that finds its way into the brain.

These viruses tend to be routine varieties, such as herpes simplex or those responsible for measles, rubella and chickenpox. Most of the time, these trigger an infection that manifests itself in the symptoms of the primary condition, such as feeling poorly or developing a rash, which the body takes a few days to deal with. But on occasions, the virus manages to cross the blood-brain barrier and infect the central nervous system. Other viruses, some carried by insects (Zika, for example), can also trigger encephalitis, but cases 
are rare in the UK.

In response to the infection, the immune system dispatches legions of white blood cells to attack and kill the pathogen, hoping to relieve the brain from the assault so that it can repair itself. A second potential cause of encephalitis is the immune system itself malfunctioning when a chemical message is sent in error or misinterpreted, causing the body’s defences to overreact to a real or imagined threat.

If that immune response is too strong, or the invader doesn’t exist, the white blood cells damage the brain instead. Their misdirected efforts create extra fluid, which settles around the neurons and prevents them from functioning normally. The brain does what it can to resist the onslaught and repair the harm, but struggles to restore order to what has been described as ‘biological chaos’. If the effects of this chaos are left unmanaged, the result for the patient can be catastrophic.


Rising rates

Encephalitis can affect more or less anybody, at any point in their lives, although it is more common among older adults and young children – those whose immune systems might be depressed or not yet properly developed.

A recent study looked at admission rates for childhood encephalitis in England from 1979 to 2011 (Iro et al, 2017). It found 16,571 cases, giving an annual admission rate of 5.97 per 100,000. The rates varied between age groups (from newborns to 19-year-olds), but was highest for infants.

Alina Ellerington, project leader at the Encephalitis Society, says that the higher incidence of the condition among infants is not a surprise: ‘We see higher rates in infants just because their immune systems are not fully formed, and in general they are more prone to pick up viruses and have illnesses.’

The study also found that the rate of admissions fell between 1979 and 1994 but then started to climb again. It is suggested that the success of the MMR vaccine initiated the downturn, and that the discovery of new types of encephalitis plus better diagnoses put rates back on the upswing.

‘Until recently it was thought that infectious encephalitis was dominant,’ says Alina. ‘But with the identification of new types of autoimmune encephalitis, it is now believed that the incidence between the two is similar.’

Dr Cheryl Hemingway, consultant paediatric neurologist at Great Ormond Street Hospital, says that they see more autoimmune cases than viral, but that’s because they normally deal with children and young people at the severe end of the scale. ‘A lot of children with encephalitis will be treated in district hospitals, make a full recovery and go home. But we generally see the ones who are not making a recovery and who create concern. So we get a treatment population that is slanted more towards autoimmune.’

Spot the signs

The early indications of encephalitis are often flu-like symptoms that appear over the course of a few hours or a day:

  • Headache
  • High temperature
  • Aching limbs
  • Generally feeling unwell

After this, the headache can get more intense and more serious symptoms begin to emerge:

  • Drowsiness
  • Confusion
  • Nausea
  • Weakness
  • Memory problems
  • Speech problems 
  • Out-of-character behaviour
  • Hallucinations
  • Seizures

People with developing encephalitis might also be sensitive to bright light and become unsteady or clumsy when moving or doing anything. In severe cases, they may lose consciousness.

Brain and Spine Foundation, 2018; NHS, 2016


Treatment types

The two types of encephalitis are treated with two types of therapy. For infectious encephalitis, treatment focuses on tackling the underlying infection. Antibiotics are used to fight bacterial infections, but viruses are more tricky and not all types have a treatment, although the most common, herpes simplex, does – the drug Acyclovir. ‘It is a simple drug given intravenously over a long period,’ says Alina, ‘but it reduces mortality immensely. Without it, the mortality rates are something like 80%; with it, they are reduced to around 20% to 30%.’

The treatment for autoimmune encephalitis differs in that it has to stop the immune system from attacking the system it is supposed to be protecting. This is known as immunotherapy, and involves the development of more complicated biological-based therapies to modify the action of the immune system.

‘Autoimmune cases are harder to treat and much more anxiety-inducing,’ says Cheryl. ‘The antibody testing, the treatment and the recovery can all take time. It very much depends on underlying causes of the case, and the degree of neurological damage. So with a viral case, the treatment will in the majority of cases eradicate the virus, the ongoing process is stopped, and the situation then consists of rehabilitation and recovery. With an autoimmune case, it is much more difficult to stop as the immune system may continue to generate antibodies, and you have to give the brain time to rebuild damaged functions – so it can take months before you have even got on top of the process. The rehabilitation process can take up to two years, though that is a small percentage of cases.’

The aftermath of this condition can be equally serious, particularly as some of the damage to the brain can prevent healthy tissue from restoring broken connections. ‘Children can be left with difficulties after encephalitis,’ says Alina. ‘Some of these changes can be persistent as the brain injury might not repair. They might experience heavy fatigue and have problems going back to school. But there are ways to cope with the changes, and it is vital that children are assessed after encephalitis. Information, advice and support 
for children and their families are very important.’

Vital steps for CPs  

  • Know the early signs of serious neurological conditions such as encephalitis.  
  • Ask for a full history of the illness from the child’s parents or carers.  
  • Warn them about the symptoms that indicate the condition is worsening, that this can happen very quickly, and that they may need to rush the child to A&E.

Recovery path

The key to a good recovery from encephalitis is rapid treatment, which in turn depends on rapid diagnosis. ‘This can reduce mortality and the consequences,’ says Alina. Cheryl agrees that this is the way to improve the prospects of children who contract encephalitis: ‘If you get on top of the inflammation early and quickly, you have a better long-term outcome.’

The tell-tale signs of impending encephalitis in children are any number of unusual neurological events. They include, says Cheryl, ‘a reduced level of consciousness, maybe a movement disorder, an onset of unusual psychiatric features, or speech issues. These are the hallmarks of autoimmune encephalitis. The hallmarks of infectious encephalitis are more likely to be seizures, a lowered consciousness and high temperature.’

Encephalitis  in numbers

She adds: ‘I would be worried about any child who has an unexplained temperature. If you can’t identify where that temperature is coming from and the child is not his or her usual self, and something seems to be evolving in the central nervous system, you need an urgent assessment.’

When it comes to recovery, Cheryl favours ‘aggressive’ rehabilitation: ‘It can be challenging, but speech and language therapy, physiotherapy and occupational therapy are key for slow but definite improvements over the long term. For families, it can be an incredibly stressful time, as a previously well child has this devastating illness with no clear indication that it is going to get better. Our experience is that they can recover and have good long-term outcomes, but it takes time.’ 

Image credit | iStock



  • The Encephalitis Society is the main charity supporting people who have had encephalitis and their families. 
    Visit encephalitis.info
  • The charity Headway works to improve life after brain injury at headway.org.uk  
  • The Children’s Brain Injury Trust supports families and professionals working with those with childhood-acquired brain injury at childbraininjurytrust.org.uk  
  • The Brain and Spine Foundation helps those with neurological problems. Go to brainandspine.org.uk



Brain and Spine Foundation. Encephalitis. See: https://www.brainandspine.org.uk/our-publications/our-fact-sheets/encephalitis (accessed 7 January 2019).

Encephalitis Society. (2017) What is encephalitis? See: https://www.encephalitis.info/what-is-encephalitis (accessed 3 January 2019).

GBD 2015 Disease and Injury Incidence and Prevalence Collaborators. (2016) Global, regional, and national incidence, prevalence, and years lived with disability for 310 diseases and injuries, 1990-2015: a systematic analysis for the Global Burden of Disease Study 2015. The Lancet 388(10053): 1545-602.

GBD 2015 Mortality and Causes of Death Collaborators. (2016) Global, regional, and national life expectancy, all-cause mortality, and cause-specific mortality for 249 causes of death, 1980–2015: a systematic analysis for the Global Burden of Disease Study 2015. The Lancet 388(10053): 1459-544.

Iro MA, Sadarangani M, Goldacre R, Nickless A, Pollard AJ, Goldacre MJ. (2017) 30-year trends in admission rates for encephalitis in children in England and effect of improved diagnostics and measles-mumps-rubella vaccination: a population-based observational study. The Lancet Infectious Diseases 17(4): 422-30. 

NHS (2016). Symptoms: encephalitis. See: https://www.nhs.uk/conditions/encephalitis/symptoms (accessed 7 January 2018).