Time trends of viral meningitis among young adults in Israel: 1978-2012.

Viral meningitis (VM) is a medical condition of public health concern, as it is a common sporadic and epidemic illness. However, there is limited data on the epidemiology of VM. The purpose of this study was to analyze long-term and seasonal trends of VM in a young adult military population. VM is a obligatory notifiable disease in the Israel Defense Forces. For the present study, the archives of the Army Health Branch were reviewed for all cases of VM from January 1, 1978 to December 31, 2012, and the annual, monthly, and seasonal rates were calculated. The annual incidence over the 35-year period showed a high peak every 3-5 years followed by a quiescent period of 2-3 years, reaching as high as 58.4 per 100,000 in 1980 and as low as 3.0 per 100,000 in 2005. This cyclic pattern has diminished over the last decade, reflected by a decline in mean incidence (10.46 per 100,000 in 2003-2012 compared to 19.79 per 100,000 in 1978-2002). Average monthly rates ranged from 1.0 cases per 100,000 soldiers in January/February to 2.2 per 100,000 in July/August. The difference in average rates between winter (1.2 cases per 100,000) and summer (1.9 cases per 100,000) was statistically significant (p < 0.001). Analysis of the long-term epidemiology of VM shows an epidemic pattern, with predominance in the warmer months. Identifying viral causes of meningitis may spare patients unnecessary treatment while prompting the introduction of public health interventions and control measures, especially in crowded settings.