General Info - Diphtheria

  • What is Diphtheria?
  • Diphtheria - Clinical Aspects
  • Diphtheria Epidemiology
  • The need for DIPNET
  • Diphtheria Hotspots
  • What is Diphtheria?

    Diphtheria is an acute infectious disease of humans affecting the upper respiratory tract and occasionally the skin, caused by the action of diphtheria toxin produced by toxigenic Corynebacterium diphtheriae or by C.ulcerans. The most characteristic feature of diphtheria affecting the upper respiratory tract is a membranous pharyngitis (often referred to as a pseudo-membrane) with fever, enlarged anterior cervical lymph nodes and oedema of soft tissues giving a "bull neck" appearance. The pseudo-membrane may cause respiratory obstruction. The toxin also affects other parts of the body including the heart and nervous systems, causing paralysis and cardiac failure. Milder infections resemble streptococcal pharyngitis and the pseudo-membrane may not develop, particularly in vaccinated individuals. The bacteria can also be carried without any symptoms at all.

    Cutaneous diphtheria usually appears on exposed parts, especially the legs. The lesions start as vesicles and quickly form small, clearly demarcated, and sometimes multiple ulcers. The lesions are usually difficult to treat and may take months or even years to heal and have been seen in UK returning travellers from exotic holiday destinations in Africa, South East Asia.


    Diphtheria - Clinical Aspects

    The bacteria, Corynebacterium diphtheriae, infects the throat and sometimes the skin. The incubation period is 5 to 9 days following exposure. Symptoms of diphtheria infection are brought about by the diphtheria toxin which can spread to the heart, central nervous system, and other organs.

    Signs and symptoms

    Early stages:
  • Sore throat
  • Low fever
  • Swollen neck glands
  • Late stages:
  • Airway obstruction and breathing difficulty
  • Shock (low blood pressure, rapid heartbeat, paleness, cold skin, sweating, and anxious appearance)
  • Risk Factors

  • Outbreak in the community
  • Crowded or unsanitary living conditions
  • Immunity gaps in adults
  • Lack of mass immunization programmes amongst children and adults at high risk
  • Lack of vaccines in many areas
  • Possible complications

  • Heart inflammation and heart failure.
  • Suffocation, due to blockage from pseudo-membrane.
  • Nerve inflammation.
  • Misdiagnosis as a less-serious infection, resulting in dangerous delay of treatment.
  • The organisms do not invade deep tissues or the blood, but, they multiply within the membrane. Within the infected area, the toxin diffuses through the mucous membrane and causes necrosis of the mucosal cells. This gives rise to a thick grey "pseudomembrane" composed of fibrin, epithelial cells, bacteria and polymorph neutrophils. The cervical lymph nodes enlarge causing oedema of the neck (a classical condition of "bullneck"). Furthermore, toxin released into the circulation and tissues causes extensive organ damage. Ultimately, neurological and myocardial complications develop. The detection of diphtheria toxin is therefore the most important test to perform on any suspect corynebacteria isolate.


    Diphtheria Epidemiology

    Mass immunisation against diphtheria in Western Europe transformed the disease to one of the first infectious diseases to be conquered. However, factors such as inadequate healthcare delivery systems, poverty and other social factors have led to diphtheria being an endemic/epidemic in many regions of the world e.g. the former USSR, the Indian subcontinent, South East Asia and South America. Diphtheria therefore, continues to be a serious health problem within these countries and presents potential health risks to other countries.

    Prompt and accurate diagnosis of diphtheria, the identification of contacts and carriers and the appropriate management of these patients is imperative. Also, the resurgence of non-toxigenic strains of C.diphtheriae causing pharyngitis and atypical symptoms such as endocarditis, septic arthritis and other forms of systemic disease have recently been indicated in the European region. The age distribution of cases has made this epidemic unusual, in that there has been a high proportion of cases among adolecents and adults. The geographical distribution of the epidemic is largely urban, except in Central Asian Republic and the Caucasus, where most of the population lives in rural areas.


    The Need for DIPNET

    A resurgence of diphtheria in the Russian Federation and NIS occurred in the 1990s with more than 50,000 cases being reported at the peak of the epidemic in 1995. Prior to 1990, only about 600 or so cases were being reported. At the request of the World Health Organization Regional Office for Europe (WHO EURO), the European Laboratory Working Group on Diphtheria (ELWGD) was formed in July 1993. Following mass immunisation campaigns, additional control measures and support from WHO, ELWGD and other agencies, diphtheria is now largely under control in the WHO EURO region. However, a network of diphtheria reference laboratories and epidemiologists/public health specialists is still required, as there may be another diphtheria resurgence in the future, despite vaccination.


    Diphtheria Hotspots 1997 - 2006 from cases reported to the WHO

    Over 100 reported cases
    Between 50 and 100 reported cases
    1-49 reported cases
    No cases reported/Information Not Available