Respiratory viruses and mycoplasma as cofactors for epidemic group A meningococcal meningitis.

To investigate the role of coincident respiratory viral and mycoplasmal agents in the pathogenesis of meningococcal meningitis, we performed a matched case-control study of 62 patients with group A meningococcal meningitis during an epidemic in Chad. Case patients were more likely than controls to have nasal colonization or infection with respiratory viruses and Mycoplasma species (matched odds ratio, 23; 95% confidence interval, 3.1 to 170). Respiratory pathogens were found more commonly in older patients with meningitis (odds ratios were 2.9 for children under age 5 years and 46.5 in those over age 15 years), consistent with the increasing risk of meningitis with age during epidemics. In controls, the presence of respiratory pathogens increased the risk of upper-respiratory-tract symptoms but did not significantly increase meningococcal carriage.