Originally published at Pediatric EM Morsels on January 7, 2020. Reposted with permission.

Follow Dr. Sean M. Fox on twitter @PedEMMorsels

It is very clear that vaccinations have improved the health of children worldwide! From Measles to Mumps and from Tetanus to Pertussis, we see the significant benefit of vaccinations. We even can administer vaccines in the Emergency Department to help reduce the impact of illness (ex, Influenza) in a community (and, maybe, make our jobs easier)! While vaccinations do reduce the burden of disease, they may also lead us to be less familiar or vigilant for those conditions. Chicken pox was once easily recognized by everyone, but now is less frequently seen and, therefore, thought of less commonly. So… as is often the case… the Morsels aim to re-establish our awareness and help us to remain vigilant! Let us take a brief moment to remember a once common concern that is, fortunately, less often seen – Meningitis in Children:

Meningitis: Basics

• Meningitis = inflammation of the meninges.

• The overall mortality has reduced over the past several decades. [Nigrovic, 2008]

• Morbidity and Mortality, however, are still concerns! [Henaff, 2017; Nigrovic, 2008]
  • Deafness
  • Epilepsy
  • Cognitive injuries and delays
  • Abscess formation
  • Death

• Cerebral Spinal Fluid (CSF) analysis and culture is vital to the evaluation and management of meningitis. [Mijovic, 2019]
  • Sorry… there is no magical blood test that will diagnosis this.
  • Normal CSF parameters (like WBC count) also vary with age… so use a reference for normal values (particularly with the neonates).
  • Do not blame pleocytosis on a traumatic tap! Save the fancy math for your kid’s high school calculus class (or help my kids with theirs).

• Most often bacterial meningitis occurs in children < 2 years of age and elderly patients > 65 years of age. [Henaff, 2017]

Meningitis: Causes (abridged)

• We are most often concerned about the potential for bacterial infection… but…
• Meningitis can be due to a wide variety of causes: [Mijovic, 2019]
  • Non-infectious
    • Leukemia and solid tumors
    • Kawasaki Disease
    • Autoimmune disorders (ex, Lupus, Behcet’s)
    • Toxins/Drugs (ex, IVIG, SMZ/TMP)
  • Infectious
    • Weird Ones
      • Protozoan
      • Helminths
      • Fungi
    • Viruses
      • Enteroviruses
      • Parechoviruses
      • Herpesviruses
      • Adenoviruses
      • Many, many more (ex, Flu, Mumps, Measles, Rubella, Rotavirus, HIV)
    • Bacteria
      • Neonates and Infants < 3 months
        • GBS
        • E. Coli
        • Listeria monocytogenes
        • Salmonella
      • Infants and Children
        • S. pneumoniae
        • N. meningitidis
        • H. influenzae
      • “At Risk” Kids (ex, VP Shunt)
        • Staph, Psuedomonas
      • Odd-ball bacteria
        • Mycobacterium tuberculosis
        • Leptospira, Treponema pallidum, Brucella, etc

Bacterial Meningits in Children

• Meningitis is easily considered in neonates and young infants.
  • They like to “hide” infections! (Never Trust a Neonate!)
  • No vaccines available to prevent their associated bacterial etiologies.

• Older children have had considerable reduction in incidences of bacterial meningitis due to vaccine usage. [Mijovic, 2019]
  • Hib Vaccination [Mijovic, 2019; Bamberger, 2014]
    • UK hospitalizations reduced from 6.72 / 100,000 children per year to 0.4 / 100,000 / yr.
    • In US, incidence declined to 0.12 cases per 100,000.
    • Majority of Hib infections are now due to non-typeable strains.
  • N. meningitidis Vaccinations [Mijovic, 2019]
    • Vaccine directed at Group C lead to 80 – 97% reduction in admissions.
    • Quadrivalent vaccine is used now and a vaccine that includes Group B (currently the most prevalent strain) is also available and effective.
  • S. pneumoniae Vaccinations [Mijovic, 2019; Dondo, 2019; Ouldali, 2018; Nigrovic, 2008; Bingen, 2008]
    • S. pneumoniae is the most common cause of bacterial meningitis in children > 3 months of age (accounts for ~ 1/3 of cases).
    • There are >90 serotypes of pneumococcus to contend with!
    • There are 7, 10, and 13-valent pneumococcal conjugate vaccines (PCV) available.
    • The 7-valent vaccine lead to 75% reduction in invasive pneumococcal disease in children < 5 years.
    • While each PCV is effective, the non-covered serotypes can emerge as the next most prevalent.
    • The overall effect of PCV is, therefore, less pronounced than the other vaccines.
    • So… even the fully vaccinated child may develop S. pneumoniae meningitis!

• Children > 5 years of age with Meningitis may have other “issues” to consider [Henaff, 2017]
  • Since this group is typically less affected, meningitis in children > 5 years of age may be related to a predisposing condition.
  • One study found ~34% of older children with pneumococcal meningitis had a predisposing risk factor. [Henaff, 2017]
    • 22% had anatomic risk factors
    • 15% had immunologic risk factors
  • Possible associated / predisposing risk factors: [Henaff, 2017; Bingen, 2008]
    • Anatomic abnormalities
      • Congenital
      • Post-traumatic (ex, CSF fistula)
      • Post-surgical (ex, Cochlear implants, VP Shunt)
      • Local infections (ex, sinusitis, mastoiditis)
    • Immunological conditions (altered immune function)
      • Genetic or Inborn Errors (ex, Sickle Cell Disease, CAH, Down Syndrome)
      • Acquired (ex, HIV, Asplenia, Diabetes, Renal disease)
  • If no clear anatomic abnormality found in older child with pneumococcal meningitis, it may be beneficial to evaluate for occult immunologic abnormality. [Henaff, 2017]
    • Peripheral Smear
    • Imaging to evaluate for lack of spleen
    • Immunoglobulin levels (IgG, IgA, IgM)
    • Pneumococcal serology
    • Complement levels (CH50, C3, C4, AP50)
    • (obviously, these are tests that don’t need to be obtained in the ED… but are mentioned here so I can sound fancy when I speak with my friends upstairs.)

Moral of the Morsel

• It may be rare, but it is still there! Don’t overlook the possibility of bacterial meningitis in the vaccinated child.
• >5 years of age? Think about why!

References