Abstract
BackgroundThe Kassena-Nankana District of northern Ghana lies in the African “meningitis belt” where epidemics of meningococcal meningitis have been reoccurring every eight to 12 years for the last 100 years. The dynamics of meningococcal colonisation and disease are incompletely understood, and hence we embarked on a long-term study to determine how levels of colonisation with different bacterial serogroups change over time, and how the patterns of disease relate to such changes.Methods and FindingsBetween February 1998 and November 2005, pharyngeal carriage of Neisseria meningitidis in the Kassena-Nankana District was studied by twice-yearly colonisation surveys. Meningococcal disease was monitored throughout the eight-year study period, and patient isolates were compared to the colonisation isolates. The overall meningococcal colonisation rate of the study population was 6.0%. All culture-confirmed patient isolates and the majority of carriage isolates were associated with three sequential waves of colonisation with encapsulated (A ST5, X ST751, and A ST7) meningococci. Compared to industrialised countries, the colonising meningococcal population was less constant in genotype composition over time and was genetically less diverse during the peaks of the colonisation waves, and a smaller proportion of the isolates was nonserogroupable. We observed a broad age range in the healthy carriers, resembling that of meningitis patients during large disease epidemics.ConclusionsThe observed lack of a temporally stable and genetically diverse resident pharyngeal flora of meningococci might contribute to the susceptibility to meningococcal disease epidemics of residents in the African meningitis belt. Because capsular conjugate vaccines are known to impact meningococcal carriage, effects on herd immunity and potential serogroup replacement should be monitored following the introduction of such vaccines.
Highlights
The highest burden of meningococcal meningitis occurs in the ‘‘meningitis belt’’ of sub-Saharan Africa, a region stretching from Senegal to Ethiopia with an estimated population of 300 million [1,2]
The observed lack of a temporally stable and genetically diverse resident pharyngeal flora of meningococci might contribute to the susceptibility to meningococcal disease epidemics of residents in the African meningitis belt
Because capsular conjugate vaccines are known to impact meningococcal carriage, effects on herd immunity and potential serogroup replacement should be monitored following the introduction of such vaccines
Summary
The highest burden of meningococcal meningitis occurs in the ‘‘meningitis belt’’ of sub-Saharan Africa, a region stretching from Senegal to Ethiopia with an estimated population of 300 million [1,2]. Outbreaks of meningococcal meningitis occur all over the world, but the highest burden of disease is in the African meningitis belt, which stretches across sub-Saharan Africa from Senegal to Ethiopia. Localized epidemics of meningococcal meningitis occur every eight to 12 years during the dry season Control of these epidemics relies on their early detection followed by mass immunization. This approach can be hard to implement in countries with limited resources, but the introduction of other control measures (for example, routine childhood immunization) requires an understanding of how the spread of different strains of N. meningitides through the community causes periodic epidemics. The researchers have studied the long-term dynamics of colonization by N. meningitidis and the occurrence of meningococcal meningitis in one region of the African meningitis belt
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
