Meningitis

1. Introduction

  • Definition: Meningitis is an acute inflammation of the meninges, the protective membranes surrounding the brain and spinal cord. It can be caused by infections (bacterial, viral, fungal, or parasitic) or non-infectious factors (autoimmune diseases, drug reactions).
  • Epidemiology: Bacterial meningitis has an incidence of 2–10 per 100,000 people annually, with the highest risk in infants, young children, and immunocompromised individuals. Viral meningitis is more common but usually less severe.
  • Significance: Meningitis can lead to severe complications, including brain damage, hearing loss, and death if not treated promptly.

2. Causes and Risk Factors

  • Causes:
    • Bacterial (most severe form):
      • Neisseria meningitidis (meningococcal meningitis).
      • Streptococcus pneumoniae (pneumococcal meningitis).
      • Haemophilus influenzae type B (Hib).
      • Listeria monocytogenes (in neonates, elderly, immunocompromised).
    • Viral (most common and milder form):
      • Enteroviruses, herpes simplex virus (HSV), varicella-zoster virus (VZV).
    • Fungal (e.g., Cryptococcus in immunocompromised patients).
    • Parasitic (e.g., Naegleria fowleri, causing amoebic meningitis).
    • Non-infectious: Autoimmune diseases (e.g., lupus), drug reactions, cancers.
  • Risk Factors:
    • Age: Infants, young children, and older adults are at higher risk.
    • Weakened immune system (HIV, chemotherapy, splenectomy).
    • Crowded living conditions (e.g., dormitories, military barracks).
    • Recent sinusitis, otitis media, or head trauma.
    • Travel to endemic regions (e.g., sub-Saharan Africa for meningococcal disease).

3. Pathophysiology

  • The causative agent invades the bloodstream and crosses the blood-brain barrier, leading to inflammation of the meninges. This triggers an immune response that causes swelling, increased intracranial pressure, and neuronal damage.

4. Symptoms and Features

  • Classic Triad (present in ~50% of bacterial meningitis cases):
    • Fever
    • Neck stiffness (nuchal rigidity)
    • Altered mental status
  • Other Symptoms:
    • Severe headache
    • Photophobia (sensitivity to light)
    • Nausea, vomiting
    • Seizures (in severe cases)
    • Skin rash (petechiae or purpura in meningococcal meningitis)
  • Infants and Young Children:
    • Bulging fontanelle, irritability, poor feeding, lethargy, high-pitched cry.

5. Complications

  • Neurological: Seizures, hearing loss, hydrocephalus, brain abscess.
  • Systemic: Septic shock, disseminated intravascular coagulation (DIC), multi-organ failure.
  • Long-term Effects: Cognitive impairment, behavioural changes, learning disabilities.

6. Diagnosis

  • Clinical Features: History and physical examination for classic signs.
  • Laboratory Tests:
    • Lumbar Puncture (CSF Analysis) (gold standard):
      • Bacterial: High white cell count, high protein, low glucose.
      • Viral: Mildly elevated white cells, normal glucose, slightly elevated protein.
    • Blood Cultures: To identify bacterial causes.
    • PCR Testing: For viral and bacterial pathogens.
    • Imaging (CT/MRI): If raised intracranial pressure is suspected before lumbar puncture.

7. Management Overview

  • Goals: Immediate antibiotic therapy (if bacterial), supportive care, and prevention of complications.
  • Approach:
    • Empirical antibiotics should be started immediately for suspected bacterial meningitis.
    • Supportive measures such as fluids, pain relief, and seizure management.

8. Treatment Options with Cost (USD)

  • Bacterial Meningitis:
    • Ceftriaxone or cefotaxime: ~$50–$150 per course.
    • Vancomycin (for resistant S. pneumoniae): ~$200–$500 per course.
    • Ampicillin (for Listeria coverage in neonates/elderly): ~$20–$50 per course.
  • Viral Meningitis:
    • Acyclovir (for HSV meningitis): ~$100–$300 per course.
    • Supportive care (fluids, pain relievers).

9. Advanced Treatment Options with Cost (USD)

  • Intensive Care Management:
    • Mechanical ventilation for severe cases: ~$10,000–$50,000 per hospital stay.
  • Surgical Interventions:
    • Ventriculostomy for hydrocephalus: ~$5,000–$15,000.

10. Pharmacological Treatment

  • First-line (Empirical Antibiotics):
    • Ceftriaxone + Vancomycin ± Ampicillin (if Listeria suspected).
  • Supportive Therapy:
    • Dexamethasone (to reduce neurological complications).

11. Medication Tables

Table 1: Doses and Side Effects

DrugIndicationDoseCommon Side Effects
CeftriaxoneBacterial meningitis2 g IV every 12 hoursGI upset, rash, allergy
VancomycinResistant bacterial strains15–20 mg/kg IV every 12 hoursNephrotoxicity, ototoxicity
AcyclovirViral meningitis (HSV)10 mg/kg IV every 8 hoursKidney toxicity, nausea
DexamethasoneAdjunct for bacterial meningitis10 mg IV every 6 hours for 4 daysGI upset, hyperglycaemia

Table 2: Brand Names and Approximate Costs (USD)

DrugBrand NamesApprox. Cost
CeftriaxoneRocephin$50–$150 per course
VancomycinVancocin$200–$500 per course
AcyclovirZovirax$100–$300 per course
DexamethasoneDecadron$10–$30 per course

12. Lifestyle Interventions

  • Maintain proper hygiene (handwashing, avoiding sharing utensils).
  • Ensure vaccination against meningococcal, pneumococcal, and Hib infections.
  • Avoid close contact with infected individuals during outbreaks.

13. Monitoring Parameters

  • Regular neurological assessments for early signs of complications.
  • Monitor for hearing loss or cognitive deficits in long-term survivors.
  • Follow-up lumbar puncture if symptoms persist despite treatment.

14. Patient Counseling Points

  • Stress the importance of early treatment to reduce complications.
  • Educate caregivers on recognising early signs of meningitis.
  • Encourage vaccination to prevent bacterial meningitis.
  • Advise close contacts to take prophylactic antibiotics if exposed.

15. Special Populations

  • Neonates (<1 month): Ampicillin + Gentamicin or Cefotaxime.
  • Immunocompromised Patients: Consider additional fungal or atypical bacterial coverage.
  • Pregnant Women: Avoid certain antibiotics; focus on preventing Listeria infection.

16. Prevention

  • Vaccines:
    • Meningococcal (MenACWY, MenB).
    • Pneumococcal (PCV13, PPSV23).
    • Hib (Haemophilus influenzae type B).
  • Post-Exposure Prophylaxis: Rifampin, ciprofloxacin, or ceftriaxone for close contacts.

15 Frequently Asked Questions (FAQs) on Meningitis

  1. What is meningitis?
    Answer: Meningitis is an inflammation of the protective membranes (meninges) surrounding the brain and spinal cord. It can be caused by bacteria, viruses, fungi, or other factors.
  2. What causes meningitis?
    Answer: The most common causes are bacterial (Neisseria meningitidis, Streptococcus pneumoniae), viral (enteroviruses, herpes simplex virus), and fungal (Cryptococcus in immunocompromised individuals).
  3. What are the symptoms of meningitis?
    Answer: Symptoms include high fever, severe headache, neck stiffness, nausea, vomiting, light sensitivity, confusion, and sometimes seizures or a skin rash (in meningococcal meningitis).
  4. How is meningitis diagnosed?
    Answer: Diagnosis is based on a lumbar puncture (spinal tap) to analyse cerebrospinal fluid (CSF), blood cultures, and sometimes imaging (CT or MRI) if raised intracranial pressure is suspected.
  5. Is meningitis contagious?
    Answer: Some types, like bacterial meningitis caused by Neisseria meningitidis, are contagious and spread through respiratory droplets. Viral meningitis can also spread but is usually less severe.
  6. Who is most at risk for meningitis?
    Answer: Infants, young children, elderly individuals, immunocompromised patients, and people in crowded environments (e.g., dormitories, military barracks) are at higher risk.
  7. What is the difference between bacterial and viral meningitis?
    Answer: Bacterial meningitis is more severe, requires immediate antibiotic treatment, and can be life-threatening. Viral meningitis is usually milder and resolves on its own without specific treatment.
  8. How is bacterial meningitis treated?
    Answer: Immediate IV antibiotics (e.g., ceftriaxone, vancomycin) and sometimes corticosteroids (dexamethasone) to reduce inflammation. Supportive care, such as oxygen and IV fluids, may also be needed.
  9. Can meningitis be prevented?
    Answer: Yes, vaccines for meningococcal, pneumococcal, and Haemophilus influenzae type B (Hib) infections significantly reduce the risk of bacterial meningitis. Practising good hygiene can also help prevent viral meningitis.
  10. How long does meningitis last?
    Answer: Viral meningitis usually resolves within 7–10 days, while bacterial meningitis requires aggressive treatment and recovery may take weeks. Severe cases may lead to long-term complications.
  11. What are the complications of meningitis?
    Answer: Potential complications include hearing loss, seizures, brain damage, hydrocephalus, learning disabilities, and, in severe cases, death.
  12. Can you get meningitis more than once?
    Answer: Yes, but it depends on the cause. Some people with weakened immune systems or anatomical abnormalities (e.g., skull fractures) may have recurrent bacterial meningitis.
  13. What should I do if I’ve been in contact with someone with bacterial meningitis?
    Answer: Close contacts of someone with Neisseria meningitidis should take prophylactic antibiotics (e.g., rifampin, ciprofloxacin, or ceftriaxone) and monitor for symptoms.
  14. What is the prognosis for meningitis?
    Answer: With early treatment, most patients recover from bacterial meningitis, though some may have long-term effects. Viral meningitis typically has a good prognosis with full recovery.
  15. When should I see a doctor for possible meningitis?
    Answer: Seek urgent medical attention if you or someone else experiences fever, neck stiffness, severe headache, confusion, seizures, or a non-blanching rash, as early treatment is critical.