The association between respiratory tract infection incidence and localised meningitis epidemics: an analysis of high-resolution surveillance data from Burkina Faso

Judith E Mueller,Yoann Madec,Maxime Woringer,Haoua Tall,Souleymane Porgho,Brice W Bicaba,Nadège Martiny

doi:10.1038/s41598-017-11889-4

Abstract

Meningococcal meningitis epidemics in the African meningitis belt consist of localised meningitis epidemics (LME) that reach attack proportions of 1% within a few weeks. A meningococcal serogroup A conjugate vaccine was introduced in meningitis belt countries from 2010 on, but LME due to other serogroups continue to occur. The mechanisms underlying LME are poorly understood, but an association with respiratory pathogens has been hypothesised. We analysed national routine surveillance data in high spatial resolution (health centre level) from 13 districts in Burkina Faso, 2004–2014. We defined LME as a weekly incidence rate of suspected meningitis ≥75 per 100,000 during ≥2 weeks; and high incidence episodes of respiratory tract infections (RTI) as the 5th quintile of monthly incidences. We included 10,334 health centre month observations during the meningitis season (January-May), including 85 with LME, and 1891 (1820) high-incidence episodes of upper (lower) RTI. In mixed effects logistic regression accounting for spatial structure, and controlling for dust conditions, relative air humidity and month, the occurrence of LME was strongly associated with high incidence episodes of upper (odds ratio 23.9, 95%-confidence interval 3.1–185.3), but not lower RTI. In the African meningitis belt, meningitis epidemics may be triggered by outbreaks of upper RTI.

Highlights

The mechanisms behind the meningitis belt epidemiology are only partially understood
Burkina Faso introduced Haemophilus influenzae type b and pneumococcal conjugate vaccine into the Expanded Program on Immunization in 2006 and 2013 respectively. These pathogens are, not involved in meningitis epidemics, pneumococci substantially contribute to the seasonality of bacterial meningitis and cause outbreaks
We used routine surveillance data at health centre resolution from 13 health districts in Burkina Faso, including weekly case counts of suspected acute bacterial meningitis[3] and monthly case counts of clinically suspected upper (URTI) and lower (LRTI) respiratory tract infections

Summary

Introduction

The mechanisms behind the meningitis belt epidemiology are only partially understood. A hypothetical explanatory model proposed that a viral respiratory infection epidemic in a given population may act as an epidemic co-factor[1], by rapidly increasing meningococcal transmission and acquisition in the nasopharynx. This would lead to a proportional increase in disease, on the background of high risk of invasive disease given carriage during the dry season[11]. Burkina Faso introduced Haemophilus influenzae type b and pneumococcal conjugate vaccine into the Expanded Program on Immunization in 2006 and 2013 respectively These pathogens are, not involved in meningitis epidemics, pneumococci substantially contribute to the seasonality of bacterial meningitis and cause outbreaks. Meningitis epidemics remain a major burden to the population and understanding the pathophysiological mechanism behind the phenomenon is needed to design appropriate and sustainable prevention strategies

Methods

Results

Conclusion