External quality assurance scheme for diphtheria diagnostics

Effective control of an uncommon vaccine-preventable disease is dependent upon prompt and early recognition and diagnosis. It is often difficult to diagnose diphtheria clinically, particularly in those countries where the disease is rarely seen. Diphtheria is often confused with other conditions, such as severe streptococcal sore throat, Vincent's angina, or glandular fever. Therefore, accurate microbiological diagnosis is crucial and complementary to clinical diagnosis. It is fundamental that EU Member States have the capacity and ability to undertake the procedures relating to the microbiological diagnosis of not only diphtheria but also the related infections caused by all potentially toxigenic strains of corynebacteria. The European Centre for Disease Prevention and Control (ECDC) recognises the importance of international collaboration for sustaining high quality diagnostics within this specialised field across the EU and catalysing research to counteract this public health threat. ECDC promotes the performance of External Quality Assurance (EQA) schemes, in which laboratories are sent simulated clinical specimens or bacterial isolates for testing by routine and/or reference laboratory methods. These exercises strengthen quality assurance systems and enable a laboratory performance to be assessed against reference methods and other peer laboratories. ECDC has a role in building and developing microbiology laboratory networks and has established the European Diphtheria Surveillance Network. One of the work packages of the laboratory aspects includes the organisation of a questionnaire assessment and an EQA dispatch for the laboratory diagnosis of diphtheria in Year One. Key findings are listed below; a description of the work involved and the outcomes of these exercises are detailed further in this report.