Why model pneumococcal carriage?

Streptococcus pneumoniae is the most common bacterial cause of pneumonia, meningitis and otitis media in children and adults world-wide. Pneumococcal infections also cause exacerbations of chronic lung disease, particularly COPD and asthma.

The difference between pneumococcal disease and carriage

An important paradox in pneumococcal infection, is that in most people pneumococci are only found harmlessly inhabiting the naso-pharynx. This common harmless state, termed pneumococcal carriage, boosts immunity to pneumococcal disease and is therefore of some benefit to the individual. As pneumococcal carriage is the means by which infection is transmitted, however, it poses a community threat. Recently acquired bacteria can lead to infection. Control of pneumococcal carriage is considered to be the key to controlling disease as it is the means of transmission and the prerequisite of disease.

We have established a method of inducing pneumococcal carriage in healthy human volunteers. 

This model of natural carriage can be used to:

  • discover how healthy subjects make immune responses to carriage
  • discover how subjects with risk factors (age, chronic lung disease) make responses to carriage and how this is different from healthy people
  • test new vaccines for their effect in experimental carriage and
  • discover how the host alters the biology of the bacteria while it is being carried