NAME OF DISEASE:     Viral meningitis
                                        Aseptic meningitis

ETIOLOGICAL AGENTS:     Mumps virus
                                                Polio virus
                                                Coxsackie B virus
                                                Echovirus
                                                Arboviruses
                                                Human Herpesvirus 1 (Herpes simplex 1 virus)
                                                Lymphocytic choriomeningitis viruses-Arenavirus
                                                Encephalomyocarditis viruses
                                                Louping ill virus
                                                Pseudolymphocytic meningitis virus
                                                Hepatitis viruses
                                                Adenovirus
                                                Rhinovirus
                                                Coxsackie A virus

THE DISEASE:

    The virus enters the body at various sites, depending on the species of the organism. Viral replication occurs at these regional sites which gives rise to a primary viremia. Target organs outside the CNS are infected as a consequence of this primary viremia. Further replication results in a secondary viremia and passage of the virus to the CNS, where it penetrates susceptible cells and replicates.

    Penetration of either the blood-CSF or the blood-brain barrier may be accomplished by means of virus-laden phagocytes migrating through blood vessels of the meninges or brain or by passage of virus particles through the choroid plexus or other areas of preferential permeability. There is always some involvement of brain tissue so the disease is really a meningoencephalitis. There are few autopsy reports of patients with uncomplicated viral meningitis as the disease is generally milder than bacterial or fungal meningitis and is self limiting.

DIAGNOSIS:

    The signs and symptoms of viral meningitis are variable. They may include:

    1.     Sudden onset

    2.     Intense frontal or retro-orbital headache

    3.     Undulating fever that never goes above 104°F

    4.     Skin rash

    At the onset of fever or shortly thereafter there is:

    5.     Malaise

    6.     Drowsiness

    7.     Sore throat

    8.     Myalgia

    9.     Nausea

    10.  Vomiting

    There may also be (but not commonly):

    11. Photophobia

    12. Tinnitus (noise in the ears)

    13. Vertigo

    14. Chest and abdominal pain

    15. Paresthesia (abnormal sensation)

    Nuchal rigidity develops and there are almost always stiffness of the back and pain on flexion. The Kernig and Brudzinski signs may or may not be elicited. Leukocyte count is normal. The CSF is transparent to slightly turbid (<500 leukocytes/mm³), glucose is normal but protein is elevated. Diagnosis requires virus isolation and serological techniques.

DIFFERENTIAL DIAGNOSIS:

    Viral meningitis may be confused with:

    1.     Bacterial meningitis

    2.     Brucellosis

    3.     Listeriosis

    4.     Leptospirosis

    5.     Tuberculosis

    6.     Syphilis

    7.     Lymphogranuloma venereum

    8.     Typhus

    9.     Mycoplasmal pneumonia

    10.   Malignancy

    11. Cat-scratch disease

PROGNOSIS:

    Full recovery with no sequelae

THERAPY:

    Bed rest, analgesic drugs, repletion and conservation of fluids and electrolytes.