meningitis and viral encephalitis

1. Dr. Leta Hirpho
Lecturer, Madda Walabu University
Lecture Note for Public Health
Students.
CNS
Infections

2. These Distinct Clinical Syndromes Include
1. Acute Bacterial Meningitis
2. Viral Meningitis
3. Encephalitis
4. Focal Infections such as Brain Abscess and Subdural
Empyema, and
5. Infectious Thrombophlebitis.

3. 3

4. Introduction
 Meningitis refers to inflammation of the leptomeninges, the connective tissue
layers in closest proximity to the surface of the brain.
 In general, viruses > bacteria > fungi > parasites, in terms of causing CNS
infections.
 Noninfectious causes: Inflammatory disorders (e.g., SLE or Kawasaki disease)
and neoplasia (e.g., leukemic meningitis)

5. Bacterial meningitis

6. Epidemiology
 Bacterial meningitis is the most common form of suppurative CNS
infection.
 In the West due to the availability of vaccines for N. meningitidis and H.
influenza, S. pneumonae has become the leading cause of bacterial
meningitis.
 However, in African and most developing countries, N. meningitidis is still
the leading cause of bacterial meningitis in adolescents and adults.

8. Etiology
8
Common causes of bacterial meningitis by age and risk factors
Age or Condition Common Bacterial Pathogens
Age < 3 months E. Coli, Group B streptococcus (S. Agalactiae),
Listeria monocytogenes
Infant (>3 months) and child Streptococcus Pneumoniae
Neisseria Meningitidis
Haemophilus Influenzae
Adults <50 (healthy) Streptococcus Pneumoniae
Neisseria Meningitidis
Adult >50 Streptococcus Pneumoniae
Neisseria Meningitidis
Listeria Monocytogenes
Skull fracture/post neurosurgery/ S. epidermidis, S. aureus, Gram-negatives
Streptococcus pneumoniae, H. infl uenzae
Immunosuppressed Listeria Monocytogenes, Gram-negatives
S. pneumoniae, Pseudomonas aeruginosa
Group B streptococcus, Staph. aureus
Source: C. Clarke, et al. Neurology: A Queen Square Textbook, 2009.

11. Risk Factors – Pneumococcal Meningitis
 There are a number of Predisposing Conditions that increase the risk
of pneumococcal meningitis, the most important of which is
Pneumococcal Pneumonia.
 Additional risk factors include coexisting
1. Acute or Chronic pneumococcal Sinusitis or Otitis Media
2. Alcoholism, Diabetes, Splenectomy,
3. Hypogammaglobulinemia, Complement Deficiency, and
4. Head Trauma with Basilar Skull Fracture and CSF rhinorrhea.

12. Enteric Gram-negative Bacilli
 Are an increasingly common cause of meningitis in individuals with
Chronic and Debilitating Diseases such as Diabetes, Cirrhosis, or
Alcoholism
 And in those with Chronic Urinary Tract Infections.
 Gram-negative meningitis can also complicate neurosurgical
procedures, particularly Craniotomy.

13. L. monocytogenes
 Has become an increasingly important cause of meningitis in
1. Neonates (<1 month of age)
2. Pregnant women
3. Individuals >60 years, and
4. Immunocompromised individuals of all ages.
 Infection is acquired by Ingesting Foods Contaminated By Listeria.

14.  Incubation period: may range from 1-10 days, but mostly the clinical
manifestations occur within in 2-4 days
 Meningitis may manifest as an acute fulminant illness that progress
rapidly in few hours or as a subacute infection that progressively
worsens over several days.
 The classic clinical triad of meningitis is fever, headache and nuchal
rigidity (neck stiffness) , which are seen in > 90 % of patients .
 Alteration in metal status can occur in > 75 % of patients and can vary
from lethargy to comma.
 Nausea and vomiting are common symptoms.
 Seizure occurs as part of the initial presentation of bacterial meningitis,
or during the course of the illness in 20-40 % of patients

15. Meningeal signs, other signs
 Neck stiffness when head is flexed passively
 Kerning’s sign: when one leg which is flexed at the hip and knee
joints, is passively extended at the knee joint, the other leg flexes
at the knee.
 Brudzinski’s sign: Upon passively flexing the head, one notices
flexion of both legs at the knees
 Some patients may have focal neurologic findings (about 30%;
hemiparesis, aphasia, visual field cuts, CN palsies)
 Funduscopic findings: papilledema, absent venous pulsations
 Skin rash: maculopapular, petechial, or purpuric

16.  A specific aetiology may be suggested by
history and physical examination.
 A petechial rash is observed in about 75%
of patients with Meningococcal Meningitis.
=Meningococcomia
 The presence of Otitis Media suggests that
the most likely organism is pneumococcal
meningitis
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17. Acute
complications
 Seizures
 Raised ICP
 Cranial nerve palsies
 Stroke
 Cerebral or cerebellar
herniations
 Thrombosis of the dural
venous sinuses
 Subdural effusion
 Ventriculitis with hydrocephalus
 SIADH

18. Diagnosis
 CSF analysis and culture
 Blood cultures (positive in 80% to 90% of cases)
* When you need to evaluate complications
 Neuro-imaging (Brain U/S, CT, MRI)
 Urinalysis and serum sodium

19. CSF Picture of Meningitis According to Etiologic Agent
LCM = Lymphocytic choriomeningitis virus Opening pressure is in mmH2O

20. Treatment of Bacterial Meningitis

21. 21
Empiric Therapy of Bacterial Meningitis
Age or Condition Antimicrobial Therapy
Infants <1 month Ampicillin + cefotaxime
Infants 1–3 months Ampicillin + cefotaxime or ceftriaxone
3 mo–50 y Cefotaxime or Ceftriaxone + vancomycin
>50 y Ampicillin + cefotaxime or Ceftriaxone + vancomycin
Immunocompromised state Vancomycin + ampicillin + ceftazidime
Posttraumatic or Postneurosurgery Vancomycin + ceftazidime

22. Viral Encephalitis

23. Definition
 In contrast to viral meningitis,
 where the infectious process and associated inflammatory response are
limited largely to the meninges,
 In encephalitis the brain parenchyma is also involved.
 Many patients with encephalitis also have evidence of
 Associated Meningitis (Meningoencephalitis) and, in some cases,
 Involvement of the Spinal Cord or Nerve Roots
(Encephalomyelitis, Encephalomyeloradiculitis).
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24. Clinical Manifestations
 In addition to the acute febrile illness with evidence of meningeal
involvement characteristic of meningitis,
 the patient with encephalitis commonly has
1. An altered level of consciousness (confusion, behavioral
abnormalities), or
2. A depressed level of consciousness ranging from mild lethargy to
coma, and
3. Evidence of either focal or diffuse neurologic signs and symptoms.
4. Focal or Generalized Seizures occur in many patients with encephalitis
 Most common focal findings are aphasia, ataxia, hemiparesis (with
hyperactive tendon reflexes), involuntary movements and cranial nerve
deficits.
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25. aImmunocompromised host.
Etiology

26. The characteristic CSF profile is
 indistinguishable from that of viral meningitis and
 typically consists of
1. a lymphocytic pleocytosis,
2. a mildly elevated protein concentration, and
3. a normal glucose concentration.
 CSF PCR, if available
 CSF Culture, usually negative (esp. in HSV-1 infections)
 Serologic studies and antigen detection, if available
 MRI, CT, and EEG: if available, done to exclude alternative diagnoses, and
assist in differentiation between focal and diffuse encephalitic process
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Diagnosis

27. Principles of treatment
 With the exception of the use of acyclovir for HSV
encephalitis, treatment of viral meningitis/encephalitis is
supportive.
 Treatment of mild disease may require only symptomatic relief.
 Headache & hyperesthesia are treated with rest, non-aspirin-
containing analgesics, a reduction in room light, noise, &
visitors.
 Treat cerebral edema or seizures if present

28. Reading Assignments
 Tuberculous Meningitis
 HIV Related Meningitis- cryptoccoccal meningitis.

29. Thank you