Climate, demographic factors and geographical variations in the incidence of invasive meningococcal disease in Italy

Abstract

We investigated the effect of climatic, demographic factors and intra-country geographical variations on the incidence of invasive meningococcal disease (IMD) in Italy. For this purpose, incidence rates of IMD cases reported in Italy between 1994 and 2012 were calculated, and a cluster analysis was performed. A geographical gradient was determined, with lower incidence rates in central and southern Italy, compared to the northern parts, where most clusters were observed. IMD rates were higher in medium-sized towns than in villages. Adults were at lower risk of IMD than children aged ⩽4 years. IMD incidence tended to decrease with increasing monthly mean temperatures (incidence rate ratio 0·94, 95% confidence interval 0·90-0·99). In conclusion, geographical variations in IMD incidence were found, where age and temperature were associated with disease occurrence. Whether geographical variations should be considered in national intervention plans is still a matter for discussion.

Keywords: IMD incidence.

Fig. 1.

Average number of invasive meningococcal disease cases by month, and distribution of the main serogroups in Italy, 1994–2012.

Fig. 2.

Mean annual incidence of meningitis per 100 000 population by province in Italy, 1994–2012.

Fig. 3.

Distribution of invasive meningococcal disease cases by municipality. Clusters are shown on the map and numbered according to the time of occurrence from the beginning of the study period.