NOTE: A surveillance case definition is a set of uniform criteria used to define a disease for public health surveillance. Surveillance case definitions enable public health officials to classify and count cases consistently across reporting jurisdictions. Surveillance case definitions are not intended to be used by healthcare providers for making a clinical diagnosis or determining how to meet an individual patient’s health needs.
Diphtheria is caused by toxin-producing Corynebacterium diphtheriae (C. diphtheriae). This disease primarily manifests as respiratory infections that may result in death, but it may also present as mild infections in non-respiratory sites, such as the skin. While respiratory diphtheria is now extremely rare, non-respiratory infections caused by toxin-producing bacteria have recently been detected. Non-respiratory disease caused by toxin-producing C. diphtheriae may act as a source of transmission and can lead to new respiratory and non-respiratory diphtheria disease; both respiratory and non-respiratory disease caused by toxin-producing bacteria require public health follow-up. This diphtheria surveillance case definition better reflects the epidemiology of diphtheria in the U.S, in order to focus efforts on identifying disease caused by toxin-producing bacteria and appropriately guide public health interventions.
Confirmatory laboratory evidence:
Supportive laboratory evidence:
Epidemiologic linkage requires direct contact with a laboratory-confirmed case of diphtheria.
Individuals without evidence of clinical criteria as described by the diphtheria surveillance case definition but for whom toxin-producing Corynebacterium diphtheriae is confirmed via laboratory testing (isolation and toxigenicity testing by modified Elek test or other validated test capable of confirming toxin-production) should not be classified as cases. These individuals are considered carriers of the bacteria and are not reportable.