Encephalitis: what is it, what symptoms does it have and how is it cured? 2026

Although it is a rare disease, each year about 600 new cases of encephalitis are diagnosed in Spain, a disease that involves inflammation of the central nervous system, mainly the brain (encephalitis), but which can also affect proximity to the meninges (meningoencephalitis) and the spinal cord (encephalomyelitis).

Today, February 22, World Encephalitis Day, the Spanish Society of Neurology remembers that the causes that generate this disease are varied, although the most frequent is still linked to viruses, ahead of bacteria and other agents.

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The symptoms

The symptoms of this disease are behavioral alterations, motor deficits, seizures, altered level of consciousness, hallucinations, drowsiness, severe headache or loss of consciousness. In babies it is especially important to also pay attention to symptoms such as vomiting, body rigidity, having a tight or protruding head and/or constant crying and hypoactivity.

In a high percentage of cases, those affected by encephalitis evolve favorably with appropriate treatment, and usually recover within a few weeks, without long-term complications.

However, there are other more serious cases that do have worse and sometimes fatal consequences. According to Dr. Santiago Trillo Senín, coordinator of the Critical and Intensivist Neurology Study Group of the Spanish Society of Neurology, “severe cases carry a high risk of mortality and highly disabling sequelae such as the development of epilepsy, motor deficits, cognitive symptoms, behavioral disorders and learning disorders, with special importance in the development of affected children.”

Hence, the early identification of this disease, as well as its causes, appears to be key both to reduce vital risk and to prevent complications, the specialist clarifies.

Causes of encephalitis

The most common cases of encephalitis are those caused by the herpes virus family (herpes simplex, varicella-zoster virus, cytomegalovirus, etc.), enteroviruses and viruses transmitted by animals (such as mosquitoes, ticks, animals with rabies, etc.). Measles, mumps or rubella viruses can also cause very serious encephalitis in unvaccinated people. There are also immune-mediated encephalitis, that is, produced by alterations in the patient's own immune system, which require treatments other than infectious encephalitis and specialized neurological surveillance.

"The signs and symptoms are the basis for us to suspect the diagnosis and to be able to perform the appropriate tests. In cases of severe neurological dysfunction, such as a low level of consciousness, the sooner we administer the treatment, the better the evolution will be, which is why it is vitally important to maintain a high level of suspicion among doctors, as well as to promote research into this disease and promote generalization and rapid access to both diagnostic and therapeutic means. In severe cases, multidisciplinary management is required in neurocritical care units. with experience in these cases, in order to improve the prognosis of the disease,” says Santiago Trillo.

"Fortunately, the incidence of this disease due to some viruses has decreased thanks to systematic childhood vaccination against measles, rubella, mumps, polio, as well as against other agents that cause encephalitis. However, in recent years, and alarmingly, there has been a rebound in cases of diseases in unvaccinated children. An increase in cases, for example of measles, could lead to an increase in the number of severe encephalitis due to this virus, with consequences For this reason, it is essential to vaccinate our children, to protect them as well as others who cannot be vaccinated. All of this, together with better health control and the development of new vaccines and antivirals, could favor a future in which this very serious disease decreases," Trillo highlights.