Immunization, Vaccines and Biologicals

Bacterial meningitis (including Haemophilus influenzae type b (Hib), Neisseria meningitidis, and Streptococcus pneumoniae)

Rationale for surveillance

Bacterial meningitis is one of the most feared infectious diseases of children and epidemic meningitis can have a devastating impact on entire populations. Until recently, antibiotic treatment of cases, and, in some situations, chemoprophylaxis of contacts, was the only means of control. Now, however, vaccines are available for prevention of the major causes of bacterial meningitis - Streptococcus pneumoniae (Sp or pneumococcus), Haemophilus influenzae type b (Hib) and Neisseria meningitidis (Nm or meningococcus). Hib and the pneumococcus are also the most common causes of severe bacterial pneumonia, a leading cause of death in young children in the developing world

Surveillance, including the laboratory investigation of suspected cases, is critical for the early detection of epidemics and formulating an appropriate response, clarifying the burden of disease and evaluating the impact of immunization services (see also the section: Principal uses of data for decision-making). Routine bacterial meningitis surveillance focuses on meningitis and other "invasive" infections such as sepsis, which can be diagnosed with microbiological tests on cerebrospinal fluid (CSF) and blood


Recommended case definition

Clinical description

Bacterial meningitis is characterized by acute onset of fever (usually > 38.5 °C rectal or 38.0 °C axillary), headache and one of the following signs: neck stiffness, altered consciousness or other meningeal signs. Hib, meningococcal meningitis and pneumococcal meningitis cannot be differentiated on clinical grounds alone

Laboratory criteria for diagnosis

Bacterial meningitis can be confirmed by three methods. (1) Culture method: isolation of a bacterial pathogen from a normally sterile clinical specimen such as CSF or blood. (2) Antigen detection methods: identification of a bacterial antigen in normally sterile fluids (i.e. CSF or blood) by such methods as latex agglutination or counterimmunoelectrophoresis (CIE). (3) Gram stain results

Case classification

Suspected: Any person with sudden onset of fever (> 38.5 °C rectal or 38.0 °C axillary) and one of the following signs: neck stiffness, altered consciousness or other meningeal sign
Probable: A suspected case with CSF examination showing at least one of the following:
- turbid appearance;
- leukocytosis (> 100 cells/mm3);
- leukocytosis (10-100 cells/ mm3) AND either an elevated protein (> 100 mg/dl) or decreased glucose (< 40 mg/dl)
Confirmed: A case that is laboratory-confirmed by growing (i.e. culturing) or identifying (i.e. by Gram stain or antigen detection methods) a bacterial pathogen (Hib, pneumococcus or meningococcus) in the CSF or from the blood in a child with a clinical syndrome consistent with bacterial meningitis

Note: Any persons with H. influenzae, meningococcus or pneumococcus isolated from CSF or blood may be reported as confirmed cases of meningitis if their clinical syndrome was meningitis (i.e. culture from normally sterile fluids is the gold standard). Culture of Hib, pneumococcus or meningococcus from a non-sterile site, such as the throat, does not confirm a case of disease, since the bacteria can grow in these other areas without causing disease


Recommended types of surveillance
  • Surveillance of suspected and confirmed cases:
    - epidemic season: routine weekly reporting of surveillance data is recommended from the peripheral level to the intermediate and central levels
    Note: During the epidemic season, it is important to have a well-functioning system for reporting cases and deaths of suspected meningitis in all provinces and to have laboratory confirmation of initial cases in every epidemic district
    - inter-epidemic season and throughout the year in countries without epidemic meningitis: routine monthly reporting of surveillance data is recommended from the peripheral level to the intermediate and central levels
    Note: The extent of surveillance during the inter-epidemic season and throughout the year in countries without epidemic meningitis varies with the capabilities of individual countries. Hospital-/clinic- or laboratory-based sentinel surveillance may be sufficient to fulfil the goals noted in the Rationale section above (see also Principal uses of data for decision-making at the end of the section). In this context, it is more important to have a well-functioning system in some areas than to have a national system that functions poorly
    - designated sites at all levels should report even if there are zero cases (referred to as "zero reporting")
  • Probable cases should also be reported if laboratory performance indicators are to be monitored

Recommended minimum data elements

Aggregated data for reporting

  • Number of suspected and confirmed (not confirmed/ Nm/ Sp or Hi/ other) cases
  • Number of deaths among suspected and confirmed (not confirmed/ Nm/ Sp or Hi/ other) cases
  • Number of Nm AC/ACW/ACWY vaccine doses administered and coverage (%)
  • Number of third doses of Hib vaccine (Hib3) administered to infants

Case-based data for reporting and investigation

  • Unique identifier
  • Date of report: dd/mm/yyyy
  • Geographical area (e.g. village, district and province names)
  • Age or Date of birth: dd/mm/yyyy
  • Sex: 1 = male; 2 = female; 9 = unknown
  • Date of admission: dd/mm/yyyy
  • Admission diagnosis
  • Outcome/discharge status: 1 = alive; 2 = discharge with extremely poor prognosis; 2 = dead; 9 = unknown
  • Vaccination status, Nm: Number of Nm AC/ACW/ACWY (indicate vaccine) doses received in the past 3 years: 1, 2, 3, 9 = unknown
  • Vaccination record, Nm vaccine: 1= card confirmed; 2=verbal report, no card; 8 = not applicable
  • Vaccination status, Hib: Number of doses received, ever: 1, 2, 3, 4, 9 = unknown
  • Vaccination record, Hib vaccine: 1= card confirmed; 2=verbal report, no card; 8 = not applicable
  • Specimen type, if specimen collected: 1=CSF; 2=blood; 3=both CSF and blood; 4=other; 6=no specimen collected; 9=unknown
  • Optional: CSF appearance: 1=clear, 2=xanthrochromic, 3=cloudy/turbid, 8=unknown
  • Optional: CSF white cell count/ml ________ (enter 88888 if not done; enter 99999 if data are missing)
  • Gram stain: 1=negative; 2=S. pneumoniae (Gram-positive diplococci); 3=H. influenzae (small, pleomorphic Gram-negative rods or coccobacilli); 4=N. meningitidis (Gram-negative, diplococci); 5=other/contaminated; 6=not done; 7=pending; 8=missing data
  • Latex agglutination: 1=negative; 2=S. pneumoniae; 3=H. influenzae type b; 4=N. meningitidis A; 5=N. meningitidis W135; 5=other/contaminated; 6=not done; 7=pending; 8=missing data
  • Culture, if obtained: 1=no growth; 2=S. pneumoniae; 3=H. influenzae; 4=N. meningitidis; 5=other/contaminated; 6=not done; 7=pending; 8=missing data
  • Anti-sera grouping or typing of culture: 1=negative; 2=H. influenzae type b; 3=N. meningitidis A; 4=N. meningitidis W135; 5=N. meningitidis C or Y; 6=indeterminate; 7=not done/pending; 8=missing data
  • Final case classification: 1=suspected; 2=probable; 3=confirmed
  • Final laboratory classification: 1=Sp, 2=Hib, 3=Hi (unknown or other type), 4=Nm A, 5=Nm W135, 6=Nm (unknown or other serogroup), 7=other/contaminated, 8=not done/undetermined

Note: The efficacy of Hib vaccines for the prevention of meningitis is more than 90% but less than 100%. The occurrence of patients with Hib meningitis who have a history of vaccination can therefore be expected. The efficacy of Nm vaccines is also less than 100%. A history of vaccination should not influence the final case classification or final laboratory classification


Recommended data analyses, presentations, reports

Aggregated data

  • Hib3 coverage (%) by year and province
  • Dates of Nm campaign, vaccine used (AC/ACW/ACWY), target age group and coverage (%), by province
  • Zero-reporting, completeness of reporting and timeliness of reporting
  • Epidemic season
    (see also: www.who.int/csr/disease/meningococcal/epidemiological/en/)
    weekly reporting of suspected and confirmed meningitis cases:
    - map: show alert and epidemic provinces (see also: Weekly Epidemiological Record 2000; 38: 306-309)
    - for every province, graph: total number of suspected cases (axis 1: columns) and case fatality ratio (axis 2: line); include an indication on the graph of when vaccination campaigns begin and end, Nm vaccine used (AC/ACW/ACWY) and coverage (%); include on the graph the serogroup distribution (A, W135) of confirmed N meningitidis cases, when available
  • Inter-epidemic season reporting and throughout the year in countries without epidemic meningitis (the following analyses can also be performed for Sp, Hib and Nm, separately, using data from confirmed cases):
    - monthly reporting, nationally and by province: total number of suspected cases (axis 1: columns) and case fatality ratio (axis 2: line)

Case-based data

same as for aggregated data plus:

  • Cases by immunization status, separately for Hib and Nm, nationally and by province
  • Epidemic season
    weekly reporting of suspected and confirmed meningitis cases:
    -> for alert and epidemic provinces, graph: suspected case incidence rate by age group (0-23m, 2-4y, 5-14y, 15-29y, 30-45y, 45+y)
    -> for alert and epidemic provinces, graph: case fatality ratio among suspected cases by age group (0-23m, 2-4y, 5-14y, 15-29y, 30-45y, 45+y)
    ->for alert and epidemic provinces, table: vaccination status (card/ verbal, no card/ no vaccination) of confirmed Nm cases, by serogroup
    -> for alert and epidemic provinces, table: vaccination status (card/ verbal, no card/ no vaccination) of deaths among confirmed Nm cases, by serogroup
  • Inter-epidemic season reporting and throughout the year in countries without epidemic meningitis (the following analyses can also be performed for Sp, Hib and Nm, separately, using data from confirmed cases):
    monthly reporting, nationally and by province, of:
    -> suspected cases by age group (0m, 1-5m. 6-11m, 12-23m, 2-4y, 5+y)
    -> case fatality ratio among suspected cases by age group (0m, 1-5m. 6-11m, 12-23m, 2-4y, 5+y)
    -> vaccination status (card/ verbal, no card/ no vaccination) of confirmed cases, by pathogen (Sp, Hib, Nm)
    -> vaccination status (card/ verbal, no card/ no vaccination) of deaths among confirmed cases, by pathogen (Sp, Hib, Nm)
  • Performance indicators of surveillance quality
    - Percentage of all probable cases for which CSF/blood was obtained for evaluation: target >=90%
    - Percentage of probable cases in which a bacterial pathogen was identified from CSF or blood:
    -> Among CSF with 10 or more white blood cells/ml3:target >=15%
    -> Among CSF with 100 or more white blood cells/ml3: target >=40%
    - Percentage of CSF isolates which are H. influenzae: target >=20%

Note: Although persons with bacterial meningitis have a wide range of CSF white blood cell counts the proportion of probale bacterial meningitis cases with identifiable bacterial causes increases with increasing CSF cell counts. For the evaluation of performance, immunization personnel may wish to determine the proportion of potential bacterial meningitis cases in which bacterial causes have been identified in one or both of the above categories. Results below the target levels suggest that some cases of bacterial meningitis are not being identified from the probable cases and that laboratory and clinical practices should be reviewed


Principal uses of data for decision-making

During the epidemic season:

  • the timely detection of epidemics
  • the timely identification of the causal pathogen
  • the provision of sufficient antibiotics for case management
  • the selection and provision of the appropriate vaccine for epidemic response

At any time, to describe the epidemiology of bacterial meningitis by etiological agent in order to:

  • determine the local disease burden (cases, deaths, disability)
  • prioritize bacterial meningitis among other diseases of public health importance
  • advocate for and implement the proper control strategies such as immunization
  • evaluate the impact of immunization services, identify areas with weak performance and provide assistance

Special aspects

During the epidemic season, it is important to have awell-functioning system for reporting cases and deaths of suspected meningitis in all provinces and to have laboratory confirmation of initial cases in every epidemic district

The extent of surveillance during the inter-epidemic season and throughout the year in countries without epidemic meningitis varies with the capabilities of individual countries. Hospital-/clinic- or laboratory-based sentinel surveillance may be sufficient to fulfil the goals noted in theRationale section above (see Principal uses of data for decision-making above). In this context, it is more important to have a well-functioning system in some areas than to have a national system that functions poorly. For example, hospital-based sentinel surveillance for bacterial meningitis is being implemented in many African countries

Surveillance in areas with appropriate clinical and laboratory capacity can provide necessary information on epidemic detection and investigation, disease burden and immunization impact. However, coverage data should be obtained nationwide. Evaluating the combination of nationwide coverage data and area-specific disease data can provide necessary information for making decisions about immunization services

Additional guidance on surveillance methodology may be obtained from:

  • Detecting meningococcal meningitis epidemics in highly-endemic African countries. Weekly Epidemiological Record 2000; 38: 306-309
  • A protocol for population-based surveillance (WHO unpublished document WHO/VRD/GEN/95.05)
  • The WHO AFRO Hib-Paediatric Bacterial Meningitis (Hib-PBM) Surveillance Network Manual, Field Test Version, July 2001 (WHO unpublished document)
  • Laboratory Methods for the Diagnosis of Meningitis Caused by Neisseria meningitidis, Streptococcus pneumoniae and Haemophilus influenzae (WHO unpublished document WHO/CDS/EDC/99.7)

COMPLETE DOCUMENT IN PDF

Share