1. Third year medical students Faculty of medicine, Mutah University
Viral Meningitis
Dr. Amin Aqel
NS I
Third year medical students
Faculty of medicine, Mutah University

2. Introduction * Meningitis is one of the most terrifying disease.
* It can be fatal in hours.
* Early symptoms resemble
self-limiting conditions
(flu and colds).

3. Meningitis…… Definition
Meningitis is an infection which causes inflammation of the membranes covering the brain and spinal cord.
Non-bacterial meningitis is often referred to as ‘aseptic meningitis’ – eg. viral meningitis
Bacterial meningitis may be referred to as ‘purulent meningitis’.
Common causes and risks
The most common causes of meningitis are viral infections that usually resolve without treatment.
Bacterial infections of the meninges are extremely serious illnesses, and may result in death or brain damage even if treated.

4. Symptoms of meningitis….
Adults and children
Babies
Neonates and the elderly often present atypically .

5. Viral (aseptic) Meningitis
Definition: A syndrome characterized by acute onset of meningeal symptoms, fever, and cerebrospinal fluid pleocytosis, with bacteriologically sterile cultures.
Laboratory criteria for diagnosis:
No evidence of bacterial or fungal meningitis
Case classification
Confirmed: a clinically compatible illness diagnosed by a physician as aseptic meningitis, with no laboratory evidence of bacterial or fungal meningitis
Comment
Aseptic meningitis is a syndrome of multiple etiologies, but most cases are caused by a viral agent.

6. Viral Meningitis Etiological Agents: Reservoirs:
Enteroviruses (Coxsackie's and echovirus): most common.
Adenovirus
Measles virus
Herpes Simplex Virus
Varicella
Arbovirus
Reservoirs:
Humans for Enteroviruses, Adenovirus, Measles, HS, and Varicella
Natural reservoir for arbovirus not known but may be birds, rodents etc.
Modes of transmission:
Primarily person to person and arthropod vectors for Arboviruses
Incubation Period:
Variable. For enteroviruses 3-6 days, for arboviruses 2-15 days
Treatment: No specific treatment available.
Most patients recover completely on their own.

7. Properties of enteroviruses
Property
Enteroviruses
Size (nm)
Capsid form
Polypeptide
RNA type
Virus replication
the Acid
Optimal temperature for growth(oC)
Non enveloped
22-30
Icosahedral
VP1, VP2, VP3, VP4
+SS-RNA
cytoplasm
Stable*pH 3 to 9 37

8. Symptoms Brain Day 0 4-14 7 - 9 10 GUT Oral Infection
viral infections of the central nervous system
viral meningitis (‘aseptic meningitis’) > enteroviruses
Common – usually benign
GUT
Brain
Oral Infection
Replication in Gut
Viraemia
Infection of CNS
Symptoms
Day 0
4-14
7 - 9 10
enterovirus meningitis

9. Transmission
Fecal – oral route: poor hygiene, dirty diapers(especially in day-care settings)
Ingestion via contaminated food and water
Contact with infected hands
Inhalation of infectious aerosols

10. Viral Meningitis 75% caused by enteroviruses Other viruses Poliovirus
Coxsackie virus (A and B groups)
Echo virus
Enterovirus
Other viruses
HSV2 (HSV1 causes encephalitis)
HIV
Lymphocytic choriomeningitis virus
Mumps
Varicella Zoster

11. Viral meningitis Summer, fall Severe headache Vomiting Fever
Stiff neck
CSF - pleocytosis (mainly mononuclear cells),
Normal protein, Normal glucose
CSF pleocytosis (mainly mononuclear cells)
Normal to slightly elevated CSF protein 18%
Normal to slightly low CSF glucose 12%
Most not reported, so true incidence not known

12. Viral Meningitis
Cannot distinguish initially from bacterial meningitis
May be preceded by a few weeks by viral gastroenteritis
Almost never involves brain (meningoencephalitis)
Patient never obtunded, no History of seizure
Disease is self-limited, resolves after 7 to 10 days without treatment
No serious sequelae

13. CSF Low numbers of WBCs : 10 to 500
PMNs predominate early, Monos or Lymphocytes later
CSF to serum glucose ratio usually = 50%
Protein may be high
Gram stain, culture and bacterial antigens negative
Enteroviral PCR positive about 70% of time

14. Laboratory Diagnosis Molecular Virus Isolation
Mainstay of diagnosis of enterovirus infection
Coxsackie B and Echoviruses can be readily grown in cell culture from throat swabs, faeces, and rectal swabs. They can also be isolated from the CSF
Coxsackie A viruses cannot be easily isolated in cell culture. They can be isolated readily in suckling mice but this is not offered by most diagnostic laboratories because of practical considerations. Molecular techniques may provide a better alternative.
Serology
Neutralization tests or EIAs are used but are very cumbersome and thus not offered by most diagnostic laboratories
Molecular
PCR

15. Approach
Treat like bacterial meningitis until the 72 hrs culture comes back negative
But
HSV meningitis:
Behavioral and personality changes
Ct scan Temporal lobe
Aciclovir iv

16. Viral meningitis - Treatment
Supportive
No antibiotics
Analgesia
Fever control
Often feel better after LP
No isolation - Standard precautions
Not clear why sometimes feel better after diagnostic LP

17. Viral meningitis - Outcomes
Adverse outcomes rare
Infants <1 year have higher incidence of speech & language delay
Neurological complications are rare
Encephalitis may develop, though this is rare.

18. Meningoencephalitis - etiology
Herpes simplex type 1
Rabies
Arthropod-borne
St. Louis encephalitis
La Crosse encephalitis
Eastern equine encephalitis
Western equine encephalitis
West Nile

19. herpes simplex encephalitis > haemorrhagic encephalitis
Sporadic
Acute
e.g. human rabies, herpes simplex virus,
herpes simplex encephalitis > haemorrhagic encephalitis
mortality (without antivirals) 70-90%
residual serious morbidity 95%
occurs at all ages

20. encephalitis Subacute sclerosing panencephalitis (measles),
+ inflammatory reaction
Chronic
subacute sclerosing
panencephalitis (SSPE) occurs in about 1 in100,000 to 1,000,000 cases of measles virus infection.
SSPE develops years (typically 6-10) following infection with measles virus and has an almost
invariably fatal outcome.

21. Japanese Encephalitis
Leading cause of viral encephalitis in Asia with 30-50,000 cases reported annually
case-fatality ratio: 30%
serious neurologic sequelae: 30%