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close this bookWHO Recommended Surveillance Standards (WHO; 1999; 157 pages)
View the documentAcknowledgements
View the documentAcronyms
View the documentIntroduction
View the documentNational Coordination of Communicable Disease Surveillance
View the documentExplanatory notes
View the documentSurveillance activities: criteria and WHO Department
View the documentCommunicable disease contacts in Regional Offices
close this folderDiseases
View the documentB20-B21-B22-B23-B24 AIDS
View the documentA22 Anthrax
View the documentA23 Brucellosis
View the documentA00 Cholera
View the documentA81.0 Creutzfeldt-Jakob disease
View the documentA90, A91 Dengue fever (A90) including Dengue haemorrhagic fever (DHF) & Dengue shock syndrome (DSS, A91)
View the documentA36 Diphtheria
View the documentB72 Dracunculiasis (Guinea worm disease)
View the documentA98.3, A98.4 Ebola-Marburg viral diseases
View the documentA83.0 Japanese encephalitis
View the documentB74 Lymphatic filariasis
View the documentB96.3 Haemophilus influenzae type b
View the documentB15-B17 Acute viral hepatitis
View the documentB20-B24 HIV infection
View the documentJ10, J11 Influenza
View the documentA96.2 Lassa fever
View the documentA48.1 Legionellosis
View the documentB55.1, B55.2 Cutaneous leishmaniasis
View the documentLeishmania / HIV co-infections
View the documentB55.0 Visceral leishmaniasis
View the documentA30 Leprosy
View the documentA27 Leptospirosis
View the documentB50-54 Malaria
View the documentB05 Measles
View the documentA39 Meningococcal disease
View the documentA87 Viral meningitis
View the documentB73 Onchocerciasis
View the documentA37.0 Pertussis
View the documentA20 Plague
View the documentA36 Poliomyelitis
View the documentA82 Rabies
View the documentA02.0 Salmonellosis
View the documentB65 Schistosomiasis
View the documentA50-52 Syphilis
View the documentA33 Tetanus, neonatal
View the documentB56-0, B56-1 African trypanosomiasis
View the documentB57 American trypanosomiasis
View the documentA15-A19 Tuberculosis
View the documentA75.3 Scrub typhus
View the documentA95.9 Yellow fever
open this folder and view contentsSyndromes
View the documentAnnex 1 Software free and in the public domain
View the documentAnnex 2 Proposed surveillance definitions
View the documentAnnex 3 Role and use of Geographic Information Systems (GIS) and mapping for epidemiological surveillance
 

A36 Diphtheria

RATIONALE FOR SURVEILLANCE

Diphtheria is a widespread severe infectious disease that has potential for epidemics. The control of diphtheria is based on the following 3 measures:

 

1. Primary prevention of disease by ensuring high population immunity through immunization.

2. Secondary prevention of spread through rapid investigation of close contacts, in order to ensure proper treatment.

3. Tertiary prevention of complications and deaths through early diagnosis and proper management.

Surveillance data can be used to monitor levels of immunization coverage (target >90%) and disease as a measure of the impact of control programmes. Recent epidemics have highlighted the need for adequate surveillance and epidemic preparedness.

RECOMMENDED CASE DEFINITION

Clinical description

An illness of the upper respiratory tract characterized by laryngitis or pharyngitis or tonsillitis, and

 

• adherent membranes of tonsils, pharynx and/or nose

Laboratory criteria for diagnosis

Isolation of Corynebacterium diphtheriae from a clinical specimen.

 

Note: A rise in serum antibody (fourfold or greater) is of interest only if both serum samples were obtained before administration of diphtheria toxoid or antitoxin. This is not usually the case in surveillance, where serological diagnosis of diphtheria is thus unlikely to be an issue.

Case classification

Suspected: Not applicable.

Probable: A case that meets the clinical description.

Confirmed: A probable case that is laboratory confirmed or linked epidemiologically to a laboratory confirmed case.

 

Note: Persons with positive C. diphtheriae cultures who do not meet the clinical description (i.e. asymptomatic carriers) should not be reported as probable or confirmed diphtheria cases.

RECOMMENDED TYPES OF SURVEILLANCE

 

• Routine monthly reporting of aggregated data of probable or confirmed cases is recommended from peripheral level to intermediate and central levels; zero reporting required at all levels

• All outbreaks must be investigated immediately and case-based data collected

• In countries achieving low incidence (usually where immunization coverage is >85% - 90%) immediate reporting of case-based data for probable or confirmed cases is recommended from peripheral to intermediate and central levels

Aggregated data on probable of confirmed cases and on immunization coverage must be reported from national level to WHO Regional Offices according to regional specifications.

RECOMMENDED MINIMUM DATA ELEMENTS

Aggregated data:

 

• Number of cases
• Number of third doses of diphtheria-tetanus-pertussis vaccine (DTP3) administered to infants

Case-based data:

 

• Unique identifier

• Geographical area (e.g., district) name

• Date of birth

• Date of onset

• Date of first treatment

• Treatment type:

 

1 = antibiotic & antitoxin; 2 = antibiotic only; 3 = antitoxin only; 4 = no or other treatment; 9 = unknown

 

• Laboratory result:

 

1 = toxigenic C. diphtheriae isolated; 2 = non-toxigenic C. diphtheriae isolated; 3 = C. diphtheriae isolated, toxigenicity unknown; 4 = C. diphtheriae not isolated; 6 = no specimen processed; 9 = unknown

 

• Total number of doses of diphtheria vaccine (DPT, DT or Td) received

• Date of last dose

• Final classification of the case:

 

1 = confirmed; 2 = probable; 3 = discarded

 

• Outcome:

 

1 = alive; 2 = dead; 3 = unknown

RECOMMENDED DATA ANALYSES, PRESENTATION, REPORTS

Aggregated data:

 

• Incidence rate by month, year, and geographic area
• DPT3 coverage by year and geographic area
• Completeness/timeliness of monthly reporting
• Proportional morbidity (compared to other diseases of public health importance)

Case-based data: same as aggregated data plus the following:

 

• Age-specific incidence rate
• Cases by immunization status, laboratory results, treatment type
• Cases treated "on time" (≤7 days of onset)
• Case-fatality rate
• Proportional mortality (compared to other diseases of public health importance)

PRINCIPAL USES OF DATA FOR DECISION-MAKING

 

• Monitor case-fatality rate and, if high, determine cause (e.g., poor case management, lack of antibiotics/anti-toxin, patients not seeking treatment in time) so that corrective action can be taken

• Determine age-specific incidence rate, geographical area, and season of diphtheria cases, to know risk groups and risk period

• Monitor incidence rate to assess impact of control efforts

• Monitor immunization coverage per geographical area to identify areas of poor programme performance

• Detect outbreaks and implement control measures

• Investigate outbreaks to understand epidemiology, determine why the outbreak occurred (e.g., vaccine failure, failure to immunize, accumulation of susceptibles, waning immunity, new toxigenic strain), and ensure proper case management

 

Note: In addition to surveillance, carefully designed serologic studies can be used to monitor the immune status of different age groups.

SPECIAL ASPECTS

Further information is available from the Expanded Programme on Immunization.

CONTACT

Regional Offices

See Regional Office contacts on section "Communicable disease contacts in Regional Offices".

Headquarters: 20 avenue Appia, CH-1211 Geneva 27, Switzerland

Vaccines and Other Biologicals (VAB)/Expanded Programme on Immunization (EPI)

 

E-mail: wengerj@who.ch / gpv@who.ch
Tel: (41 22)791 4511/4410
Fax: 4193 or (4122) 7910746 attn VAB
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