Summary

Background:

Bacterial meningitis (BM) remains a considerable cause of morbidity.

Objectives:

To evaluate BM incidence rate trends in diverse age groups.

Methods:

We conducted a retrospective cohort study based on the Israeli national registry. Inclusion criteria were acute admissions 2000 to 2019 with primary diagnosis of BM. Predefined age groups were neonates (≤ 30 days), infants (31 days to 1 year), younger children (1 ≤ 5 years), older children (5 ≤ 18 years), and adults (≥ 18 years). Average annual incidence rates per 100,000/year were calculated for the entire period and by decade. Incidence rates for neonates and infants were calculated per 100,000 live births (LB).

Results:

There were 3039 BM cases over 2 decades, 60% were adults. The overall BM incidence rate was 2.0/100,000/year, neonates, 5.4/100,000/year LB, infants 17.6/100,000/year LB. First year of life incidence rate (neonates and infants combined) was 23.0/100,000/year, younger children 1.5/100,000/year, older children 0.9/100,000/year, and adults 1.8/100,000/year. All age groups presented a decrease in incidence rate (last decade vs. previous) except neonates, which increased by 34%. Younger and older children presented the most considerable decrease: 48% and 37% (last decade vs. previous).

Conclusions:

Adults showed the highest number of BM cases. The incidence rate was highest during the first year of life (neonates and infants combined). All age groups, except neonates, showed a decreasing trend. Younger and older children presented the most considerable decrease, most likely attributable to vaccination. The observed increase in BM incidence rate in neonates may influence whether preventive strategy is considered.