Difterie

Difterie, or diphtheria, is a contagious bacterial disease caused by Corynebacterium diphtheriae. Toxigenic strains produce an exotoxin that can injure tissues and cause systemic effects. The disease most commonly affects the upper respiratory tract and nose, but cutaneous forms can occur.

The infection spreads mainly through respiratory droplets and close contact with contaminated secretions. After colonization of the throat or nasal passages, toxin production can lead to a thick, grayish-white pseudomembrane on the tonsils, pharynx, or nasal passages and can cause sore throat, fever, and sometimes swelling of the neck. The toxin can affect the heart and nervous system, leading to myocarditis or neuropathies days to weeks after infection.

Diagnosis relies on clinical suspicion supported by laboratory tests, such as throat or nasopharyngeal culture or PCR for C. diphtheriae. Determining whether the strain produces toxin may guide management.

Treatment requires rapid administration of diphtheria antitoxin to neutralize circulating toxin, along with antibiotics (commonly erythromycin or penicillin) to eradicate the bacteria. Patients should be isolated to prevent further spread, and airway support may be needed in severe cases. Antitoxin is derived from animal or human sources and carries potential hypersensitivity risks.

Prevention is primarily through vaccination. The DTaP vaccine protects children, with Td or Tdap boosters recommended for adolescents and adults approximately every 10 years. Close contacts may receive prophylactic antibiotics and, if not adequately immunized, vaccination.

Difterie has become rare in countries with high vaccination coverage, but outbreaks can occur in unvaccinated populations. Historically, the development of diphtheria antitoxin marked a turning point in treatment and public health response.