Diphtheria (from the Greek word for leather which refers to the tough pharyngeal membrane that is the clinical hallmark of infection) is an acute, communicable disease caused by the gram-positive bacillus Corynebacterium diphtheriae. The membrane is created by a thick, inflammatory exudate. A rare bacterial infectious disease marked by the formation of a membrane over the tonsils, uvula, soft palate, and posterior pharynx and occasionally on the skin.

Clinical features:DIPHTHERIA

DIPHTHERIA

• it is caused by Corynebacterium diphtheriae.It may be anterior nasal, faucial, laryngeal. Skin and conjunctiva may also be involved.
• The bacteria produces an exotoxin which forms a grey membrane over the tonsils, pharynx, larynx. There is congestion, edema, local tissue destruction, and en largement of regional lymph nodes.
• There are features of toxaemia.
• The exotoxin can cause myocarditis and nerve dam age leading to paralysis.
• Mortality is 10%.
• The bacteria may be gravis, mitis, intermedius. The gravis bacteria produces severe infections. Source of infection is a case with running nose.

PATHOPHYSIOLOGY

• Symptomatic diphtherial infection results from two factors: Local noninvasive inflammation of the respiratory tract or skin Local and systemic effects of a potent diphtheria exotoxin

• 14 – 28 days from onset of disease.

Age:
• 1-5 years
• Immunity is high in the population Incubation period 2 – 6 days.

Clinical features:DIPHTHERIA

• It is common to base a presumptive diagnosis upon initial clinical features of the illness.
• There is a membrane on the tonsils and pharynx.
• The earliest pharyngeal finding is generally mild erythema.
• Diphtheria should be considered in patients with pharyngitis, low-grade fever and/or cervical adenopathy.
• This typically progresses to areas of white exudate, which coalesce to form an adherent gray pseudomembrane that bleeds with scraping.
• Both culture of C. diphtheriae and a positive toxin-production assay are required for confirmation of the diagnosis.
• Affects the tonsils, pharynx, larynx, nasal passages. There is sore throat, difficulty in swallowing, low grade fever.
• There is hoarseness and shrill cough.

Schick test DIPHTHERIA

Schick test DIPHTHERIA

• Definitive diagnosis of diphtheria requires isolation of C. diphtheriae from respiratory tract secretions or cutaneous lesions.
• This is an intradermal test for antitoxin and hyper sensitivity.
• An intradermal Schick test toxin is injected into the forearm and inactivated toxin is injected into the other arm as control.
• A negative reaction is seen in immune persons.
• A positive reaction is a red flush of 1-5 cm. in one or two days in the test arm.
• A pseudopositive reaction is a red flush in both the arms.

Clinical features:DIPHTHERIA of skin

Treatment of Diphtheria :

• The treatment of respiratory diphtheria combines administration of diphtheria antitoxin with antibiotic therapy
• Diphtheria antitoxin 50,000 unit 1M / IV
• Penicillin 2.5 lakhs unit 6 hrly or erythromycin 250 mg 6 hrly for 5 days
• Carriers are given erythromycin for 10 days. Diphtheria antitoxin in horse serum 10,000 – 1,00,000 units intramuscular in 2 doses.

Vaccination of Diphtheria, DPT

Vaccination of Diphtheria:

• DPT – Diphtheria, Pertussis, Tetanus is given as-l  doses at 4-week intervals and booster at 2 years given
• Fever may occur after vaccination.
• Supportive measures including electrocardiographic monitoring and careful airway management are also important due to the risk of myocarditis and airway obstruction.