Diphtheria: forgotten, but not gone

Diphtheria is an acute, highly infectious, vaccine-preventable and previously endemic disease whose etiologic agent is Corynebacterium diphtheriae. Diphtheria may manifest as an upper respiratory tract infection, a cutaneous infection or as an asymptomatic carrier state. The most common sites of infection are the pharynx and the tonsils, with common clinical manifestations that include sore throat, malaise, cervical lymphadenopathy and low-grade fever. Absorption and dissemination of C.diphtheriae from the respiratory tract can cause disseminated infection and may lead to cardiac or neurological toxicity. The cornerstone of treatment for diphtheria is diphtheria antitoxin. Early treatment is critical as the degree of protection is inversely proportional to the duration of the illness before its administration. Routine childhood vaccination virtually eliminated diphtheria in most industrialised countries. However, in the pre-vaccination era, diphtheria was the most common infectious cause of death in Australia. A case of diphtheria in Brisbane in April 2011 and two recent positive cultures in regional Victoria underscore the need for heightened awareness of C.diphtheriae as an important pathogen. In order to prevent the re-emergence of diphtheria in Australia, public health measures are required to increase immunity in early school leavers and the adult population, and to ensure that travellers to endemic regions are fully immunised. Health policy-makers and clinicians alike should not underestimate the importance of primary vaccination and booster vaccination against diphtheria among healthy adults and travellers.