Overview of meningitis

Related Diseases & Conditions

• Viral meningitis

  Summary

  Viral meningitis is one of the most common infections of the central nervous system (CNS), and is the most common cause of aseptic meningitis. Causative agents include nonpolio human enteroviruses (most commonly), herpes simplex virus, mumps, varicella zoster virus, arboviruses such as West Nile, HIV, and (rarely) influenza.​[2]​ Viral meningitis must be distinguished from bacterial meningitis, which is associated with significant morbidity and mortality. Common symptoms include headache, photophobia, neck stiffness, fever, nausea, and vomiting. Key risk factors include age (most commonly seen in infants and young children, but also young adults and older people) and exposure to insect vectors.
• Bacterial meningitis

  Summary

  Bacterial meningitis is a serious inflammation of the meninges caused by various bacteria. Streptococcus pneumoniae, Neisseria meningitidis, andHemophilus influenzae type b (Hib) are the predominant causative pathogens.[3] It commonly affects extremes of age because of impaired or waning immunity. Common symptoms include headache, neck stiffness, fever, vomiting/nausea, and altered level of consciousness or cognition. Key risk factors include crowding, exposure to pathogens, cranial anatomic defects, cochlear implants, sickle cell disease, and immunocompromising conditions.
• Meningococcal disease

  Summary

  Meningococcal infections are caused by N meningitidis, a gram-negative diplococcus that colonizes the nasopharynx. The highest rates of invasive meningococcal disease are in children under age 5 years, especially those under age 1 year, with a second peak occurring in 11-24 year olds and a third peak in people age >65 years.[4]​ Meningococcal infection may progress rapidly to septic shock with hypotension, acidosis and disseminated intravascular coagulation. Common symptoms include fever, vomiting or nausea, irritable/unsettled, and headache. Key risk factors include young age, complement deficiency, use of eculizumab and ravulizumab, and immunoglobulin deficiency.
• Fungal meningitis

  Summary

  Fungal meningitis presents as a progressive, life-threatening, chronic or subacute meningitis that is most commonly caused by Cryptococcus neoformans. Occurs most commonly in immunosuppressed individuals and is often accompanied by systemic involvement.The incidence of fungal meningitis is increasing worldwide due to the increasing number of patients immunosuppressed by pharmacologic agents and the ongoing burden of HIV-associated cryptococcal meningitis in resource-limited countries.[5]​ Common symptoms include progressive and/or severe headache, meningismus, symptoms of hydrocephalus, behavioral or personality change, and reduced visual acuity and papilledema. Key risk factors include immunosuppression; exposure to disturbed soil, chicken guano, or bat caves; neutropenia; impaired phagocytic function; and neurosurgery.
• Evaluation of rash in children

  Summary

  Rash in children is common. The differential diagnoses are extensive, ranging from self-limiting conditions to life-threatening illnesses such as meningococcal disease. Meningococcal disease classically presents with abrupt onset of fever and malaise, progressing rapidly (within 24 hours) to signs and symptoms of septicemia and/or meningitis. A generalized macular rash may be the initial presenting feature of meningococcal disease, although this progresses to a more purpuric rash. Initial considerations in evaluating a rash in children include its morphology, duration, and distribution. Age, sex, family history, drugs, known allergies, and exposures are also of primary importance.
• Extrapulmonary tuberculosis

  Summary

  An infectious disease caused by Mycobacterium tuberculosis that occurs in organ systems other than the lungs. Almost any organ system may be affected by extrapulmonary tuberculosis, including the lymph nodes, CNS, bones/joints, genitourinary tract, abdomen (intra-abdominal organs, peritoneum), and pericardium. Epidemiologic risk factors include birth in high tuberculosis-prevalent countries, exposure at place of residence/work in an institutional setting, and homelessness.Tuberculous meningitis results from hematogenous spread of M tuberculosis with the development of submeningeal or intrameningeal foci called Rich foci. With rupture of a Rich focus into the subarachnoid space, meningitis develops. Common symptoms include enlarged lymph nodes, pleuritic chest pain, skeletal pain, urinary symptoms, abdominal swelling and pain. Key risk factors include exposure to tuberculosis; born in Asia, Latin America, or Africa; HIV infection; immunosuppressive drugs; hematologic or head/neck malignancy; end-stage renal disease; apical fibrosis; and very young age.
• Rabies

  Summary

  An acute viral encephalomyelitis caused by negative-sense RNA viruses of the Lyssavirus genus, which is transmitted by animal bites, mainly dogs in developing countries and bats in other countries including the US. The main burden of disease is located in developing countries in Asia and Africa.[6]​ Clinically, rabies has two forms: encephalitic (furious) and paralytic. Both forms have a prodrome of fever, chills, malaise, sore throat, vomiting, headaches, and paresthesias. In encephalitic rabies, this is followed by early-onset behavioral changes and late-onset paralysis. In the paralytic form, the behavioral changes are absent. Key risk factors include a recent scratch or bite from a known vector in a rabies-endemic country, recent contact with a bat, and occupation or recreation exposure.
• Syphilis infection

  Summary

  A common sexually transmitted infection caused by the spirochete bacteriumTreponema pallidum, subspeciespallidum. Neurosyphilis is characterized by a chronic, insidious inflammation of the meninges, and is caused by CNS invasion by the T pallidum bacteria, which may occur at any stage of infection. Infection is typically acquired through direct person-to-person sexual contact with an individual who has early (primary or secondary) syphilis.[7]​ Early neurosyphilis syndromes are usually the result of meningovascular involvement; late neurosyphilis may occur due to meningovascular involvement or direct infection of the brain and spinal cord parenchyma. Clinical presentation is often asymptomatic, but can manifest in a number of ways. Symptoms of headache, meningismus, hearing loss, seizures, or neuropathy suggest neurologic involvement.