Encephalitis is a devastating neurologic syndrome that is characterized by inflammation of the brain parenchyma. While infectious encephalitis is most often identified, the cause remains unknown in up to 50% of cases. An acute clinical presentation may suggest more virulent viruses and bacteria, while a subacute presentation is more often associated with indolent bacteria, fungi, parasites, and autoimmune and paraneoplastic causes. More than 90% of viral encephalitis is caused by herpes simplex virus (HSV), varicella-zoster virus (VZV), and enteroviruses (Venkatesan, 2014), with typical bacterial causes of cerebritis and abscesses consisting of polymicrobial streptococci, gram-negative bacilli, and Staphylococcus aureus infections. Early recognition and treatment for HSV, bacterial, Plasmodium falciparum, and rabies infections are critical and potentially life saving. Diagnosis requires a combination of clinical, laboratory, and neuroimaging findings (Venkatesan, 2014).
Last Update: August 2019