ABSTRACT
Viral encephalitis Most cases of encephalitis are due to viruses. Herpes simplex encephalitis (HSE) is the commonest, but a wide range of virus infections may result in brain damage. Encephalitis may be caused by direct viral invasion of the brain (e.g. HSV, rabies), or by an immune response to infection which cross-reacts with brain antigens (post-infectious encephalitis). Diagnosis is made by clinical features, including history (travel, exposure to animals) and neuroimaging. Genome amplification from cerebrospinal fluid may identify the specific viral cause. Immediate high-dose intravenous aciclovir is essential in case a patient has HSE. Mumps, measles and rabies encephalitis are all preventable by appropriate vaccination. Risk of arthropod-borne encephalitis may be reduced by appropriate precautions to reduce mosquito and tick bites.
