Invasive Meningococcal outbreak toolbox

Invasive Meningococcal outbreak toolbox

Updated | October 2024

Welcome to the Invasive Meningococcal Outbreak toolbox

Key reference documents

Case definitions

WHO suggested invasive meningococcal outbreak case definition

Suspected case
Any individual with sudden-onset fever and any of the following:
• neck stiffness
• Brudzinski’s sign
• Kernig’s sign
• altered mental state or impaired consciousness
• photophobia
• focal neurological deficits
 
• new-onset seizures (in adults)
• bulging fontanelle (in infants)
• haemorrhagic skin rash
• hypotension or shock and signs of hypoperfusion
• severe headache
• gastrointestinal complaints (vomiting and/or diarrhoea)
• constitutional symptoms (arthralgia, myalgia, body and/or leg pain)


Probable case
A suspected case with any of the following:
• Gram-negative diplococci identified from any normally sterile body fluid (e.g. CSF specimen or blood culture)
• antigen detection test positive for N. meningitidis from any normally sterile body fluid (e.g. CSF specimen or blood culture)
• CSF with a cloudy, turbid or purulent appearance
• CSF WBCs >1000/mm3
• CSF WBCs >100/mm3 and CSF–blood glucose ratio <0.4
• CSF WBCs >100/mm3 and CSF glucose <2.2 mmol/L or <40 mg/dL
• CSF WBCs >100/mm3 and CSF total protein >1 g/L or >100 mg/dL

Confirmed case
  • A suspected or probable case with a positive culture or molecular test (PCR) for N. meningitidis from any normally sterile body fluid (e.g. CSF or blood)
Excluded case
  • Suspected case where laboratory test shows another pathogen.

WHO suggested invasive meningococcal disease (IMD) surveillance case definition

Suspected IMD case
  • .Any individual with a suspected clinical diagnosis of invasive meningococcal disease
Probable IMD case
A suspected case with any of the following:
• Gram-negative diplococci identified from any normally sterile body fluid (e.g. CSF specimen or blood culture)
• antigen detection test positive for N. meningitidis from any normally sterile body fluid (e.g. CSF specimen or blood culture)
Confirmed IMD case
  • A suspected or probable case with a positive culture or molecular test (PCR) for N. meningitidis from any normally sterile body fluid (e.g., CSF or blood) 

 

WHO other definition

Definition of a contact of a case

Close contacts should be defined based on context-specific considerations and available resources. In the presence of an index case, during the 7 days before symptom onset and until 24 hours after initiation of appropriate antibiotic therapy, people at increased risk of infection include:
  • individuals with prolonged exposure while in close proximity (less than 1 metre) to the index case (e.g., household contacts);
  • individuals directly exposed to oral secretions of the index case (e.g. via kissing, mouth-to-mouth resuscitation, endotracheal intubation).

1. A normally sterile fluid is defined as blood, cerebrospinal fluid, joint fluid or other sterile site.

 

 

 

Data collection tools

Training

Other resources