Published online by Cambridge University Press: 05 March 2013
Diphtheria is a disease caused by toxin producing strains of Corynebacterium diphtheriae.
The problem in Africa
Serious diphtheria always seems to have been relatively uncommon in Africa, possibly due to repeated skin infections due to C. diphtheriae (van Geldermalsen and Wenning, 1993). Widespread use of diphtheria toxoid vaccine (against the toxin), has probably also contributed to a low rate of significant diphtheria in Africa and it is now rare, with vaccine rates of DTP vaccine running at around 70 per cent (Arevshatian et al., 2007). Some cases do occur, however, and it is worth being aware of the typical presentation of diphtheria.
Classically patients present with a very sore throat or with a very sore nasopharynx with discharge which is bloody. The key to suspecting the diagnosis is to examine the throat, or the nose, which will show a grey–white pseudomembrane which on touching it with a swab is adherent and bleeds when you try to pull it away. Where possible, try and culture diphtheria, but seeing a typical pseudomembrane is sufficiently diagnostic that it should be treated as diphtheria for practical purposes. Nasopharyngeal diphtheria causes two sets of problems, local and general, both caused by toxin. The local effects of diphtheria are to cause massive inflammation of the throat and eventually larynx. Externally this may be seen with swelling and inflammation of the neck (bull neck). This can cause local pressure on the airways particularly around the larynx, which can lead to complete or near complete obstruction.