MM 455-456, 586-588; ID 1092-1100
 
 

NAME OF DISEASE:     Viral meningitis
                                               Aseptic meningitis
 

OVERVIEW:

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.
 

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

PATHOLOGY:

Very limited and not of diagnostic importance.
 

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.