Welcome to the Diphtheria Outbreak Toolbox

Key reference documents

Diptheria Fact Sheet (Geneva: World Health Organization; 2023)
Immunization, Vaccines and Biologicals: Diphtheria (Geneva: World Health Organization; 2020).
Diphtheria: Questions and Answers (Geneva: World Health Organization; 2023).
Diphtheria vaccine: WHO position paper – August 2017 (World Health Organisation; 2017).
Diphtheria: Surveillance standards for vaccine-preventable diseases (Geneva: World Health Organization; 2018).

Case definitions

WHO suggested outbreak case definition

Suspected case:

any person with an illness of upper respiratory tract with:
- pharyngitis, nasopharyngitis, tonsillitis or laryngitis; and
- adherent pseudomembrane of the pharynx, tonsils, larynx and/or nose.¹

Final case classification²:

Laboratory-confirmed case: a person with Corynebacterium spp. isolated by culture and positive for toxin production, regardless of symptoms³
- Laboratory-confirmed classic respiratory diphtheria cases meet the suspected case definition and are laboratory-confirmed as defined above.
- Laboratory-confirmed mild respiratory/asymptomatic diphtheria cases have some respiratory symptoms such as pharyngitis and tonsillitis, but no pseudomembrane, or no symptoms (usually identified via contact tracing).
- Non-respiratory laboratory-confirmed diphtheria cases have a skin lesion or non-respiratory mucosal infection (for example, eye, ear

Epidemiologically linked case: a person that meets the definition of a suspected case and is linked epidemiologically to a laboratory-confirmed case⁴
Clinically compatible case: a person that meets the definition of a suspected case and lacks both a confirmatory laboratory test result and epidemiologic linkage to a laboratory-confirmed case.
Discarded case/non-case: suspected case that meets either of these criteria: Corynebacterium spp. but negative Elek test (non-toxigenic Corynebacterium) OR negative PCR for the diphtheria toxin (tox) gene.

WHO surveillance case definition

Diphtheria: Surveillance standards for vaccine-preventable diseases (Geneva: World Health Organization; 2018 (pp. 4–5)).

_{1. A diphtheria pseudomembrane is an exudate that is greyish, thick, firmly adherent and patchy to confluent. Dislodging the pseudomembrane is likely to cause profuse bleeding. Some countries may choose to expand the suspected case definition to include suspect cases without a pseudomembrane.}

_{2. Refer to Figure 1: Diphtheria: Surveillance standards for vaccine-preventable diseases (Geneva: World Health Organization; 2018).}

_{3. PCR is normally considered a complementary tool to the gold standard of culture and Elek testing.}

_{4. Epidemiological link: In this situation, a person has had intimate respiratory or physical contact with a laboratory-confirmed case within the 14 days prior to onset of sore throat}

Data collection tools

Case investigation form: PDF | Word
Line list: Recommended data elements: Diphtheria: Surveillance standards for vaccine-preventable diseases (Geneva: World Health Organization; 2018 (pg. 8-9)).
Electronic tool: Not available.

Laboratory confirmation

Laboratory testing for diphtheria in outbreak settings: Interim guidance ( Geneva: World Health Organization; 2024)
Diphtheria: Surveillance standards for vaccine-preventable diseases (Geneva: World Health Organization; 2018).
Field Guide for Preparedness and Response to Diphtheria Outbreaks ( Geneva: World Health Organization; 2023).
Control of diphtheria, pertussis, tetanus, Haemophilus influenzae type B, and hepatitis B: field guide. Washington (DC): Pan American Health Organization; 2005).
WHO laboratory manual for the diagnosis of diphtheria and other related infections (World Health Organisation; 2021).

Response tools and resources

Diphtheria: Surveillance standards for vaccine-preventable diseases (Geneva: World Health Organization; 2018).
WHO laboratory manual for the diagnosis of diphtheria and other related infections (World Health Organisation; 2021).

Training

Diphtheria: Clinical management of respiratory diphtheria (Geneva: World Health Organization; 2018).