Health: a study shows that seasonal variations can increase the presence of bacteria responsible for meningitis in humans
A study carried out in Côte d'Ivoire by the meningitis research group at the Centre Suisse de Recherches Scientifiques en Côte d'Ivoire (CSRS) has shed light on the spatio-temporal dynamics of the oropharyngeal microbiome in Ivorian schoolchildren aged between 8 and 12. This research made it possible to characterise seasonal variations in the micro-organisms present in the throat and the impact of climate on certain families of bacteria containing pathogenic species such as Neisseria (Neisseria meningitidis), Streptococci (Streptococci pneumoniae) and Haemophilus (Haemophilus influenzae). These bacteria, commonly found in the throat, can under certain conditions become pathogenic and cause meningitis, a serious and often fatal infection capable of spreading in epidemics.
The study was published in December 2024 in the journal Nature-Scientific Report (read the full publication here: https://www.nature.com/articles/s41598-024-81829-6 ). The respiratory tract, and more specifically the throat, is home to a multitude of micro-organisms that generally coexist symbiotically with humans. One of these micro-organisms is Neisseria meningitidis. The main aim of this study was to analyse how micro-organisms in the throat vary according to season and geographical location, and to determine the impact of these variations on the local immune system, particularly with regard to the presence of meningococci (another name for the Neisseria meningitidis bacterium). The research was carried out on a cohort of schoolchildren divided between the northern (Korhogo) and southern (Abidjan) regions of Côte d'Ivoire, two geographical areas characterised by distinct climatic conditions. The north of Côte d'Ivoire, located in the meningitis belt, is associated with sudden climatic changes and generally lower humidity levels, while the south of the country enjoys a more stable climate that is more humid throughout the year. The study revealed significant differences in the throat microbiome between children at the two sites studied, Abidjan and Korhogo. Children in Abidjan showed higher bacterial diversity, generally associated with better health, while children in Korhogo showed more frequent carriage of bacteria of the genus Neisseria, although carriage of Neisseria meningitidis remained very low overall. No carriage of Neisseria was detected in Abidjan. The preliminary results of the study indicate that significant fluctuations in microbial populations in the throat occur according to the seasons... Indeed, correlations between climatic factors (temperature, wind speed and humidity levels) and changes in the microbiome were explored in this study and revealed significant correlations between certain factors such as relative humidity and Nesseria abundance; this negative correlation indicates that Neisseria abundance decreases when humidity increases.
Major implications for public health
This study is of vital importance for public health in Côte d'Ivoire and other at-risk regions. The microbiota is recognised for its influence on the state of health of populations. Understanding its composition and variations will open up new avenues for more targeted preventive strategies, such as vaccination, awareness campaigns during seasons that are favourable for the colonisation of potential pathogens such as Neisseria meningitidis, or even the development of probiotics adapted to the Ivorian context.
Analysis of the spatio-temporal dynamics of the oropharyngeal microbiome is helping to refine our understanding of the environmental and seasonal factors that influence the presence of potentially dangerous bacteria, explains Dr Kanny Diallo, head of the research group. These findings reinforce the importance of ongoing microbiological surveillance to accurately identify the pathogens circulating in our populations.
About the study
The study was carried out by a team of researchers from CSRS and Afrique One in collaboration with institutions specialising in microbiology, genomics and public health, namely WACCBIP (Ghana), UFHB, INPHB, Université Nangui Abrogoua, LANADA (Côte d'Ivoire), Imperial College London (UK) and University of Cape Town (South Africa). The study is part of a wider framework for monitoring respiratory health and preventing serious infections in vulnerable populations, particularly children.
