Infection of the pharynx, larynx, nose or skin caused by the bacterium Corynebacterium diphtheriae
Typical symptoms include fever usually less than 39°C, sore throat with rapid onset, oedema in the infected region spreading outside the tonsillae, and nausea (in one fourth of the patients).
Myocarditis and polyneuropathy may occur as complications.
Contact through saliva with a patient having diphtheria is required for infection; the disease does not spread by droplets.
A sample is obtained from under the exudate into 2 transport tubes. Bacterial culture requires a special medium; the laboratory should be informed beforehand.
Epidemiology
A dangerous communicable disease with potential for causing serious epidemics, preventable by vaccination. Find out about local policies and requirements concerning notification to relevant authorities.
The disease spreads via respiratory secretions (nasal secretions, saliva), but also via direct contact with wounds and other secretions; a near contact with a patient or a carrier is needed for infection.
High-risk areas of diphtheria infection are South Asia and Southeast Asia, Middle East, South America, Africa and Eastern Europe.
Symptoms
Local inflammation with copious pharyngeal exudates, grey or dark mucosal adhering exudates and soft tissue oedema. In children this phase of the disease may result in the obstruction of the airway.
The systemic disease caused by bacterial toxin starts 1-2 weeks after the local symptoms. The toxin affects the heart (myocarditis, arrhythmias particularly during the second week of the disease) and the nervous system (paralyses, neuritis 2-7 weeks after disease onset). If the patient survives the acute phase of the disease he/she usually recovers without sequelae.
Also toxin-producing strains of Corynebacterium ulcerans and C. pseudotuberculosis may cause the same kind of systemic disease as the one caused by C. diphtheriae.
Diagnosis
The need for treatment is decided on the basis of the history and clinical picture (severe, exudative pharyngitis, particularly in a patient who has visited any of the aforementioned high-risk areas 1-7 days before the onset of the disease).
The diagnosis is confirmed by bacterial culture of an exudate sample taken from beneath the coating into an appropriate Stuart transport tube (special culture medium, inform the laboratory in advance). For detecting the toxin gene, a sample is taken into a dry tube; the result of the nucleic acid detection test will be available even already on the same day.
Whenever diphtheria is suspected, consult an infectious disease specialist regarding the diagnostics and treatment of the acute phase. Also notify the relevant authorities without delay.
Treatment
Severely ill patients with diphtheria are treated in a hospital in a single room, following droplet and contact precautions; patients with mild symptoms can be treated at home.
In children, the patency of the airway must be ensured in the initial phase.
Take throat diphtheria bacterial cultures from close contacts, after which
treat them with antibiotics (benzathine penicillin, 600 000-1.2 million units as a single dose intramuscularly or roxithromycin, chlarithromycin, azithromycin, or erythromycin at a standard dose for 7-10 days) and
vaccinate them.
When a suspicion of diphtheria is aroused, antitoxin treatment must already be started before the confirmation of the diagnosis. The antitoxin is only beneficial if started within 3 days from the onset of symptoms.
Prevention
Vaccination prevents complications caused by the toxin but it does not prevent infection.
If the basic diphtheria vaccinations have been given in childhood, the protection is over 90% before the age of 20 years.
If the dtap vaccine (diphtheria, tetanus, and acellular pertussis) has been given at the age of 25, a dT booster (diphtheria and tetanus) is recommended at the age of 45 and 65 years. After this, a booster vaccination is recommended every 10 years.
Travellers should be given the basic series of three vaccinations, if they have not been vaccinated previously. A booster vaccination is sufficient in adults if they are over 30 years of age and have previously received a full basic series of three vaccinations.
Find out about local recommendations concerning vaccination, boosters and their timing, which may differ from the information contained herein.