Pneumococcal diseases are caused by Streptococcus pneumoniae (also called pneumococcus) and are a major cause of morbidity and mortality.

Streptococcus pneumoniae is an encapsulated gram-positive coccus. The capsule is the most important virulence factor of Streptococcus pneumoniae; pneumococci that lack the capsule are normally not virulent.  It is a bacterial pathogen that colonises the upper respiratory tract and can cause the following types of illnesses: disseminated invasive infections, including bacteremia and meningitis; pneumonia and other lower respiratory tract infections; and upper respiratory tract infections, including otitis media and sinusitis.

Eight to ten capsular types cause about 66% of serious infections in adults and about 80% of invasive infections in children but over 90 different types are known.

Pneumococcal disease particularly affects the very young, the elderly and those with an absent or nonfunctioning spleen and those with other causes of impaired immunity.

Recurrent infections may occur in association with skull defects, cerebrospinal fluid leaks, cochlear implants or fractures of the skull.

How does disease transmission occur?

• By aerosol, droplets or direct contact with respiratory secretions of someone carrying the organism
• The organism may then spread into the sinuses or middle ear cavity (causing sinusitis or otitis media), lungs (causing pneumonia) or invasive infections (bacteraemic pneumonia, bacteraemia and meningitis)
• Transmission usually requires either frequent or prolonged close contact
• There is a seasonal variation in pneumococcal disease, with peak levels in the winter months

Did you know?

Before the introduction of routine vaccination pneumococcal infection killed approximately one child every week in England and Wales.

Click on the links below to learn more about some of the specific conditions pneumococcal disease can cause including, symptoms and who is at risk?

Otitis Media

Meningitis & Septicaemia

Pneumonia