Diphtheria is an infectious disease caused by aerobic bacteria, Cornyebacterium diphtheria. It is now more common in children below the adolescents and adults above the age of 40. It usually affects the respiratory system, skin and rarely causes a systemic infection. It is highly communicable however incidence and mortality of the disease have greatly reduced over the years because of childhood vaccination with DPT (Diphtheria, Pertussis, and Tetanus) vaccine which confers 80% immunity. Even when the vaccine doesn’t confer immunity, it greatly reduces the severity of the disease. The immunity conferred by the vaccine wanes and it is advisable to renew vaccination after 10 years.
RISK FACTORS
These include overcrowding, malnutrition, lack of or incomplete immunization, immunosuppression, low herd immunity, low socioeconomic status, travel to endemic areas, exposure to carriers, infected persons or animals.
CLINICAL FEATURES
Symptoms usually begin 2-5 (or 1-10) days following infection. For respiratory diphtheria, symptoms initially are non-specific and mild but may later become severe. Mimicking a typical viral upper respiratory tract infection, it usually starts with sore throat and fever. Afterward, a pseudomembrane (a highly infectious grey or white patch composed of mixed dead cells and organisms) may develop anywhere along the respiratory tract and be big enough to occlude the airway and cause a cough and difficulty in breathing. Removal of this membrane reveals a bleeding mucosa. Other symptoms include weakness, fatigue, cyanosis, painful swallowing, blood-stained or foul-smelling nasal discharge, wheezing, and halitosis. Enlargement of cervical lymph nodes coupled with the effect of the pseudomembrane causes the neck to swell.
Cutaneous diphtheria usually presents with non-healing ulcers covered with a grey membrane and often co-infected with other bacteria.
Systemic involvement may lead to cardiac toxicity (myocarditis, endocarditis) and neurologic toxicity (neuropathy, cranial nerve deficits).
MANAGEMENT
For diagnosis, it is imperative to isolate the causative organism via a Microscopy, culture and sensitivity test, polymerase chain reaction assay. Clinical criteria for diagnosis include an upper respiratory tract infection with a sore throat, low-grade fever, and presence of a pseudomembrane.
A complete blood culture should be done and can show moderate leukocytosis. A chest radiograph and neck radiography, ultrasonography or computed tomography may be done.
A serum troponin level check can assess the severity of myocarditis.
The patient may need interventions such as endotracheal intubation and/or tracheostomy to relieve airway obstruction and prevent aspiration.
Cases should be isolated and emergency care should be instituted promptly. Antibiotics and antitoxin administration should be ensured. Cutaneous wounds should be properly cared for and the patient should be strictly monitored.
