Diseases caused by Haemophilus influenzae

Haemophilus influenzae produces both invasive and non invasive infections

Invasive diseases are usually caused by capsulated strains. The bacilli are protected from phagocytes by the capsule and spread through blood. The various invasive infections are:

• Meningitis – most common
• conjunctivitis
• laryngoepiglottitis
• pneumonia
• pericarditis
• endocarditis
• arthritis
• bacteremia

Non invasive diseases usually occur as superadded infections and are often caused by non capsulated strains. It spreads locally in the mucous membranes and are associated with respiratory infections. The various conditions include:

• otitis media
• sinusitis
• acute exacerbation of chronic bronchitis, bronchiectasis