Communicable disease factsheets

Diphtheria

Diphtheria is caused by a toxigenic strain of the bacteria Corynebacterium diphtheriae. This fact sheet covers: the disease and its agent; spread of infection; prevention; surveillance and reporting.

The disease and its agent

Diphtheria is caused by a toxigenic strain of the bacteria Corynebacterium diphtheriae. The disease mainly affects the upper respiratory tract, where an inflammatory exudate forms a greyish membrane which can cause severe respiratory obstruction. The bacteria produce a toxin which may cause neuropathy and cardiomyopathy, and can be fatal. Death occurs in about 10 per cent of cases.

Spread of infection

Diphtheria is spread via respiratory droplets or contact with soiled articles from an infected person. The incubation period is 2 to 5 days, and the disease remains communicable for up to four weeks. Shedding of the organism by carriers may persist for longer than this.

Prevention

Diphtheria vaccines provide effective protection against the disease by stimulating the production of antibodies against the Diphtherial toxin. In Australia, Diphtheria vaccine in the form of DTP (a combined diphtheria, tetanus and pertussis vaccine) at 2, 4, 6 and 18 months of age, and at 4 to 5 years of age. Td (ADT), a combined Diphtheria-tetanus vaccine, is used for the 15-19 year old and adult doses.

Surveillance and reporting

Diphtheria is a notifiable disease and treating GP's and/or diagnosing laboratories should report cases to their State and Territory health departments. Reported cases are collected through the National Notifiable Diseases Surveillance System, for national reporting in the Communicable Diseases Intelligence (CDI).

Diphtheria has almost been eradicated from Australia; reporting of coses is therefore of considerable public health importance. The latest reported case of diphtheria was an imported case in a traveller to the Northern Territory in March 2001 but before that, Australia had not recorded a case of diphtheria since 1993.