Diphtheria is a nasopharyngeal and skin infection caused by Corynebacterium diphtheriae. Toxigenic strains of C. diphtheriae produce a protein toxin that causes systemic toxicity, myocarditis, and polyneuropathy. The toxin is associated with the formation of pseudomembranes in the pharynx during respiratory diphtheria
Mode of transmission
The secretions and discharges from infected person or carrier are the main source of infection. The infection is transmitted by contact or via droplets of secretion. The portal of entry is commonly the respiratory tract.
The incubation period of the disease is 2-5 days.
C. diphtheriae proliferate and liberate powerful exotoxin which is the principal cause of systemic and local lesions. The exotoxin causes necrosis of the epithelial cells and liberates serous and fibrinous material which forms a grayish white pseudomembrane which bleeds on being dislodged. The surrounding tissue is inflamed and edematous. The organs principally affected by the exotoxin include the heart, kidney and myocardium.
- The child has a toxic look.
- The commonest form is faucial/tonsillopharyngeal diphtheria in which there is redness and swelling over the fauces. The exudates coalesce to form a grayish white pseudomembrane, which extends to surrounding areas.
- The cervical lymph nodes are enlarged leading to a bull neck appearance.
- Sore throat
- Muffled voice are frequently present
- In laryngotracheal diphtheria, the membrane over the larynx leads to brassy cough, stridor and respiratory distress
- The commonest complication is respiratory failure due to occlusion of the airways by the membrane.
- Myocarditis generally occurs by second week of illness and can lead to symptoms of congestive cardiac failure, arrhythmias and sudden death.
- Neurological complications include: (i) palatal palsy ; (ii) ocular palsy :(iii) loss of accommodation (iv) generalized polyneuritis
Swab from the oropharynx and larynx.