Meningoencephalitis is a medical condition

Disease

A disease is an abnormal condition affecting the body of an organism. It is often construed to be a medical condition associated with specific symptoms and signs. It may be caused by external factors, such as infectious disease, or it may be caused by internal dysfunctions, such as autoimmune...

 that simultaneously resembles both meningitis

Meningitis

Meningitis is inflammation of the protective membranes covering the brain and spinal cord, known collectively as the meninges. The inflammation may be caused by infection with viruses, bacteria, or other microorganisms, and less commonly by certain drugs...

, which is an infection

Infection

An infection is the colonization of a host organism by parasite species. Infecting parasites seek to use the host's resources to reproduce, often resulting in disease...

 or inflammation

Inflammation

Inflammation is part of the complex biological response of vascular tissues to harmful stimuli, such as pathogens, damaged cells, or irritants. Inflammation is a protective attempt by the organism to remove the injurious stimuli and to initiate the healing process...

 of the meninges

Meninges

The meninges is the system of membranes which envelopes the central nervous system. The meninges consist of three layers: the dura mater, the arachnoid mater, and the pia mater. The primary function of the meninges and of the cerebrospinal fluid is to protect the central nervous system.-Dura...

, and encephalitis

Encephalitis

Encephalitis is an acute inflammation of the brain. Encephalitis with meningitis is known as meningoencephalitis. Symptoms include headache, fever, confusion, drowsiness, and fatigue...

, which is an infection or inflammation of the brain

Brain

The brain is the center of the nervous system in all vertebrate and most invertebrate animals—only a few primitive invertebrates such as sponges, jellyfish, sea squirts and starfishes do not have one. It is located in the head, usually close to primary sensory apparatus such as vision, hearing,...

.

Causes

Causative organisms include protozoans, viral

Virus

A virus is a small infectious agent that can replicate only inside the living cells of organisms. Viruses infect all types of organisms, from animals and plants to bacteria and archaea...

 and bacteria

Bacteria

Bacteria are a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria have a wide range of shapes, ranging from spheres to rods and spirals...

l pathogen

Pathogen

A pathogen gignomai "I give birth to") or infectious agent — colloquially, a germ — is a microbe or microorganism such as a virus, bacterium, prion, or fungus that causes disease in its animal or plant host...

s.

Specific types include:

Bacterial

• Listeria monocytogenes
• Neisseria meningitidis
  Neisseria meningitidis
  Neisseria meningitidis, often referred to as meningococcus, is a bacterium that can cause meningitis and other forms of meningococcal disease such as meningococcemia, a life threatening sepsis. N. meningitidis is a major cause of morbidity and mortality during childhood in industrialized countries...
  
  
• Rickettsia prowazekii
  Rickettsia prowazekii
  Rickettsia prowazekii is a species of gram negative, Alpha Proteobacteria, obligate intracellular parasitic, aerobic bacteria that is the etiologic agent of epidemic typhus, transmitted in the feces of lice. In North America, the main reservoir for R. prowazekii is the flying squirrel. R...
  
  

Viral

• Tick-borne meningoencephalitis
  Tick-borne meningoencephalitis
  Tick-borne encephalitis is a viral infectious disease involving the central nervous system. The disease most often manifests as meningitis, encephalitis, or meningoencephalitis. Although TBE is most commonly recognized as a neurological disorder, mild fever can also occur...
  
  
• West Nile virus
  West Nile virus
  West Nile virus is a virus of the family Flaviviridae. Part of the Japanese encephalitis antigenic complex of viruses, it is found in both tropical and temperate regions. It mainly infects birds, but is known to infect humans, horses, dogs, cats, bats, chipmunks, skunks, squirrels, domestic...
  
  
• Mumps, a relatively common cause of meningoencephalitis. However, most cases are mild, and mumps meningoencephalitis generally does not result in death or neurologic sequalae.
• HIV
  HIV
  Human immunodeficiency virus is a lentivirus that causes acquired immunodeficiency syndrome , a condition in humans in which progressive failure of the immune system allows life-threatening opportunistic infections and cancers to thrive...
  
  , a very small number of individuals exhibit meningoencephalitis at the primary stage
  Acute HIV infection
  Acute HIV infection or primary HIV infection is the second stage of HIV infection. It occurs after the incubation stage, before the latency stage and the potential AIDS succeeding the latency stage....
  
   of infection.

Other/multiple

• Granulomatous meningoencephalitis
  Granulomatous meningoencephalitis
  Granulomatous meningoencephalitis is an inflammatory disease of the central nervous system of dogs and, rarely, cats. It is a form of meningoencephalitis. GME is likely second only to encephalitis caused by canine distemper virus as the most common cause of inflammatory disease of the canine...
  
  
• Other causes include antibodies targeting amyloid beta
  Amyloid beta
  Amyloid beta is a peptide of 36–43 amino acids that is processed from the Amyloid precursor protein. While it is most commonly known in association with Alzheimer's disease, it does not exist specifically to cause disease...
  
   peptide
  Peptide
  Peptides are short polymers of amino acid monomers linked by peptide bonds. They are distinguished from proteins on the basis of size, typically containing less than 50 monomer units. The shortest peptides are dipeptides, consisting of two amino acids joined by a single peptide bond...
  
   protein
  Protein
  Proteins are biochemical compounds consisting of one or more polypeptides typically folded into a globular or fibrous form, facilitating a biological function. A polypeptide is a single linear polymer chain of amino acids bonded together by peptide bonds between the carboxyl and amino groups of...
  
  s which have been used during research on Alzheimer's disease
  Alzheimer's disease
  Alzheimer's disease also known in medical literature as Alzheimer disease is the most common form of dementia. There is no cure for the disease, which worsens as it progresses, and eventually leads to death...
  
  .
• The fungus, Cryptococcus neoformans
  Cryptococcus neoformans
  Cryptococcus neoformans is an encapsulated yeast that can live in both plants and animals. Its teleomorph is Filobasidiella neoformans, a filamentous fungus belonging to the class Tremellomycetes. It is often found in pigeon excrement....
  
  , can be symptomatically manifested within the CNS
  Central nervous system
  The central nervous system is the part of the nervous system that integrates the information that it receives from, and coordinates the activity of, all parts of the bodies of bilaterian animals—that is, all multicellular animals except sponges and radially symmetric animals such as jellyfish...
  
   as meningoencephalitis with hydrocephalus
  Hydrocephalus
  Hydrocephalus , also known as "water in the brain," is a medical condition in which there is an abnormal accumulation of cerebrospinal fluid in the ventricles, or cavities, of the brain. This may cause increased intracranial pressure inside the skull and progressive enlargement of the head,...
  
   being a very characteristic finding due to the unique thick polysaccharide
  Polysaccharide
  Polysaccharides are long carbohydrate molecules, of repeated monomer units joined together by glycosidic bonds. They range in structure from linear to highly branched. Polysaccharides are often quite heterogeneous, containing slight modifications of the repeating unit. Depending on the structure,...
  
   capsule of the organism.

Protozoal

• Primary amoebic meningoencephalitis
  Primary amoebic meningoencephalitis
  Primary amoebic meningoencephalitis is a disease of the central nervous system caused by infection from Naegleria fowleri.-Presentation:...
  
   e.g., Naegleria fowleri
  Naegleria fowleri
  Naegleria fowleri is a free-living excavate form of protist typically found in warm bodies of fresh water, such as ponds, lakes, rivers, and hot springs. It is also found in soil, near warm-water discharges of industrial plants, and unchlorinated swimming pools in an amoeboid or temporary...
  
  , Balamuthia mandrillaris
  Balamuthia mandrillaris
  Balamuthia mandrillaris is a free-living leptomyxid amoeba which is known to cause amoebiasis in humans, especially the deadly neurological condition known as granulomatous amoebic encephalitis . Balamuthia has not been definitively isolated in nature, but it is believed to be distributed...
  
  , Sappinia diploidea
  Sappinia diploidea
  Sappinia diploidea is a free-living amoeba species.-Clinical significance:It is capable of causing infectious disease in humansSpecifically, it can cause amebic encephalitis.-External links:...
  
  .
• Trypanosoma brucei
  Trypanosoma brucei
  Trypanosoma brucei is a parasitic protist species that causes African trypanosomiasis in humans and nagana in animals in Africa. There are 3 sub-species of T. brucei: T. b. brucei, T. b. gambiense and T. b. rhodesiense.These obligate parasites have two hosts - an insect vector and mammalian host...
  
  
• Toxoplasma gondii
  Toxoplasma gondii
  Toxoplasma gondii is a species of parasitic protozoa in the genus Toxoplasma. The definitive host of T. gondii is the cat, but the parasite can be carried by many warm-blooded animals . Toxoplasmosis, the disease of which T...
  
  (sporozoa) (immunocompromised patients)

Ameobic pathogens exist as free-living protozoans. Nevertheless, these pathogens cause rare and uncommon CNS infections. N. fowleri produces primary amebic meningoencephalitis (PAM). The symptoms of PAM are indistinguishable from acute bacterial meningitis. Other amebae cause granulomatous amebic encephalitis (GAE), which is a more subacute and can even a non-symptomatic chronic infection. Ameobic meningoencephalitis can mimic a brain abscess, aseptic or chronic meningitis, or CNS malignancy.

Prognosis

The disease is associated with high rates of mortality

Death

Death is the permanent termination of the biological functions that sustain a living organism. Phenomena which commonly bring about death include old age, predation, malnutrition, disease, and accidents or trauma resulting in terminal injury....

 and severe morbidity.

Notable cases

It was the claimed cause of death of the popular British TV presenter Christopher Price

Christopher Price (broadcaster)

Christopher Nicholas Price was the original host of British celebrity news show Liquid News.-Early life and career:...

.

In May, 2009 former Premier of New South Wales (Australia) Morris Iemma

Morris Iemma

Morris Iemma , is a former Australian politician and 40th Premier of New South Wales, succeeding Bob Carr after he resigned on 3 August 2005. Iemma led the Australian Labor Party to victory in the 2007 election before resigning as Premier on 5 September 2008, and as a Member of Parliament on 19...

 was admitted to hospital with meningoencephalitis.

In Popular Culture

Meningoencephalitis is credited as the virus that decimates the world in the 2011 film Contagion

Contagion (film)

Contagion is a 2011 American medical thriller disaster film directed by Steven Soderbergh. The film has an ensemble cast that includes Marion Cotillard, Matt Damon, Laurence Fishburne, Jude Law, Gwyneth Paltrow, Kate Winslet, and Bryan Cranston. Contagion follows the rapid progress of a lethal...

. In the film the virus is known as Meningoencephalitis Virus One (MEV-1).