Pneumococcal disease is a leading cause of serious illness in children and adults. It is caused by a common bacterium, Streptococcus pneumoniae (also known as pneumococcus), which can target different parts of the body to cause non-invasive diseases such as pneumonia, otitis media and sinusitis, as well as invasive pneumococcal disease (IPD), including bacteraemia and meningitis. To read more about the types of pneumococcal disease click here.

How does it spread?

Pneumococcal disease is spread by the bacterial pathogen Streptococcus pneumoniae, an encapsulated Gram-positive coccus. The capsule is the most important virulence factor of Streptococcus pneumococci that lack the capsule are normally not virulent.

It is relatively common for healthy people to carry pneumococcal bacteria in the back of the nose or throat without causing disease: carriage is estimated to be in excess of 40% in pre-school children, falling to <10% in young adults in the UK.

Disease transmission can occur by aerosol, droplets or direct contact with respiratory secretions of someone carrying the organism.  The organism then may 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 also a seasonal variation in pneumococcal disease, with peak levels in the winter months.

According to the World Health Organization (WHO), pneumococcal disease is the world’s number one vaccine-preventable cause of death among infants and children younger than 5 years of age. To find out more about preventing pneumococcal disease click here.

How common is it?

Pneumococcal disease is a leading cause of illness and death worldwide. Although infection can affect anyone, young children, older people and certain at-risk groups of people have an increased risk of developing the disease. To read more about who is at risk of pneumococcal infection click here.

Pneumococcal disease tends to be more common during winter and when influenza and other respiratory viruses are circulating. In the UK there are up to 500,000 adult cases of pneumonia each year, of which an estimated 42% are due to Streptococcus pneumoniae infection.

In 2008, pneumococcal disease killed up to 12,750 people in the UK over the age of 65. This is comparable to the number of deaths in the UK due to colon cancer, breast cancer and prostate cancer each year (10,188, 12,141 and 10,175, respectively, in 2008).

Pneumococcal disease also represents an increasing burden on the NHS. Between 22-42% of adults with community acquired pneumonia (CAP) in the UK are admitted to hospital. Furthermore, the number of hospital admissions for CAP has more than doubled since 2002/3. To find out more about the impact of pneumococcal disease download our fact sheet.

What are serotypes?

There are more than 90 different types of pneumococci, known as serotypes, but only a small number actually cause pneumococcal disease. Understanding which serotypes cause disease can aid the development of appropriate vaccines.

A recent review of the literature found that 6 to 11 serotypes account for around 70% of cases of invasive pneumococcal disease (IPD) among children under 5 years old.

In the UK,before the introduction of the pneumococcal conjugate vaccine into the childhood schedule, the serotypes covered by the vaccine accounted for 70% of cases of IPD in the under 5’s(2005-2006). This dramatically reduced to only 24% in 2007-2008 after the vaccine was launched.

Antibiotics are almost always used to treat pneumococcal infections. However, there is concern that pneumococci are becoming increasingly resistant to commonly- used antibiotics. As pneumococcal bacteria become harder to treat because of this resistance, prevention of pneumococcal disease by immunisation becomes even more important. The uses of vaccines coupled with prudent use of antibiotics are important if we are to see an impact on resistant pneumococci in the community.

To read more about serotypes and vaccination pneumococcal disease click here.

Key points

• Pneumococcal disease is spread by the bacterium Streptococcus pneumoniae
• In 2008, pneumococcal disease killed up to 12,750 people in the UK over the age of 65
• There are more than 90 different types of pneumococci, known as serotypes