Seasonal paradox in acute meningitis at Nawabshah

ABSTRACT

To assess the reasons for paradoxical increase in cases of meningitis in the summer of the year 2001. Design: An observational study. Place and Duration of Study Medical Unit III, Peoples Medical College Hospital, Nawabshah, Pakistan, from 1st January, 2001 to 31st December, 2001. Subjects and A total number of 229 cases of meningitis were admitted throughout the year with typical clinical features or CSF findings. Maximum number [179] was noted from April to July, which was alarming. The reason for this change was assessed in these cases. One hundred and seventy-nine cases of meningitis presented from 1st April to 31st July 2001. They were predominantly males n= 107 [59.7%] with age range of 15 to 64 years. Presenting symptoms were fever and headache in all and altered sensorium in 160 [89%] cases with positive signs of meningeal irritation in 175 [97.8%]. Cerebrospinal fluid examination revealed altered biochemistry and neutrophil leucocytosis in all cases. Organism was identified in 139 [77.65%] cases on gram staining. Culture was done only in 61 [34.07%]. Predisposing factors were smoking in 93 [52%] and diabetes in 17 [9.5%] cases. Five female patients were pregnant. Common organisms detected were gram positive diplococci [Streptococcus pneumoniae] in 83 [59.7%], gram negative diplococci [Nisseria meningitides] in 51 [36.7%] and Haemophilus influenzae in 5 [3.6%]. As the frequency of isolates were approximately same as in other seasons, the increased in meningitis cases during summer was probably due to hot and dry weather causing low absolute humidity