Subacute and chronic meningitis (SCM) presents significant diagnostic challenges, with numerous infectious and non-infectious inflammatory causes. This study examined patients aged 16 and older with SCM admitted to referral centers for neuroinfections and neuroinflammations in Mashhad, Iran, between March 2015 and October 2022. Among 183 episodes, tuberculous meningitis was the most common infectious cause (46.5%), followed by Brucella meningitis (24.6%). The cause of SCM was definitively proven in 40.4%, presumptive in 35.0%, and unknown in 24.6% of cases. In-hospital mortality was 14.4%, and 30.5% of survivors experienced unfavorable outcomes (Glasgow Outcome Scale 2–4). Patients with unknown causes had a significantly higher risk of death compared to those with presumptive or proven diagnoses (risk ratio 4.18). This study emphasizes the diagnostic difficulties of SCM, with one-quarter of cases remaining undiagnosed and over one-third having only a presumptive diagnosis. Improving diagnostic methods could potentially enhance prognosis and reduce mortality.

We evaluated the incidence rate of culture-positive central nervous system tuberculosis (CNS TB) in France in 2007 and its time trend between 1990 and 2007. We used a capture–recapture analysis by using data recorded in 2007 by the mandatory notification system and the national network of the National Reference Centre (NRC). The 2007 sensitivity of the NRC was 79·4%. The previous sensitivity for 2000 (75·6%) and that for 2007 yielded a pooled estimate of 77·4% (95% confidence interval 64·8–88·0), which was used to extrapolate the number of culture-positive CNS TB cases from those reported in four surveys (1990, 1995, 2000, 2007). The extrapolated number of culture-positive CNS TB cases fell from 90 to 35 between 1990 and 2007, and the extrapolated incidence rates fell from 1·6 to 0·55 cases/million (P < 0·001). This favourable trend should be closely monitored following the change of the BCG vaccination policy in 2007.

Tuberculous meningitis (TBM) is a severe complication of tuberculosis and occurs mainly during early childhood. The incidence rate of TBM varies with season, and serum vitamin D levels, which are dependent on sunlight, might play a role. We studied the association between TBM incidence rate and hours of sunshine in Cape Town, South Africa and found a significant association between the incidence rate of TBM and hours of sunshine 3 months earlier (incidence rate ratio per 100 sunshine hours 0·69, 95% confidence interval 0·54–0·88, P = 0·002). The association supports the hypothesis that vitamin D might play a role in the pathophysiology of TBM. Further prospective studies in which vitamin D status is measured are necessary to determine causality.