Dr Effua Usuf a post-doctoral Clinical Epidemiologist working with the Disease Control and Elimination Theme is the first author of a recent publication “Pneumococcal carriage in rural Gambia prior to the introduction of pneumococcal conjugate vaccine: a population-based survey”, funded by the MRC. This article was first published  in the Tropical Medicine and International Health (TMIH) journal.
As part of Effua’s PhD, the main aim of the study was to describe pneumococcal carriage within a rural community prior to routine pneumococcal conjugate vaccine (PCV). The project was part of the Pneumococcal Surveillance Project, headed by Dr Grant Mackenzie.

The study was conducted in Upper River Region (URR) in an area where a large pneumococcal conjugate vaccine (PCV) trial, the PCV 9 vaccine trial took place. The prevalence of nasopharyngeal pneumococcal carriage was high as previously described in other studies in the Gambia. The result further showed that there was no difference in the overall carriage of pneumococci between vaccinated and unvaccinated children, 8 years after primary vaccination with three doses of PCV 9.

Pneumococcal serotypes included in PCV13 accounted for about half the pneumococcal serotypes identified in the study. Therefore, it is  expected that with the introduction of PCV13 into the Gambian immunisation programme, there will be a substantial decrease in pneumococcal carriage and disease, since carriage is a necessary step on the pathway to disease.

The result of the study is an important baseline for further studies in this community where there is ongoing surveillance for invasive pneumococcal carriage. In comparison with carriage studies that will be conducted after routine introduction of PCV, we will be able to assess changes in pneumococcal carriage after widespread use of PCV in the study area. This information would be a useful supplement to the sureveillance data.

“Working in Basse with the wonderful PSP surveillance team was a great experience for me. I am glad to be part of the extensive work on the pneumococcal carriage and diseases in The Gambia and look forward to now explore the relationship between serotypes in carriage and those in invasive disease in the post PCV era”.