Geotemporal Analysis of Neisseria meningitidis Clones in the United States: 2000–2005

Abstract

BackgroundThe detection of meningococcal outbreaks relies on serogrouping and epidemiologic definitions. Advances in molecular epidemiology have improved the ability to distinguish unique Neisseria meningitidis strains, enabling the classification of isolates into clones. Around 98% of meningococcal cases in the United States are believed to be sporadic.MethodsMeningococcal isolates from 9 Active Bacterial Core surveillance sites throughout the United States from 2000 through 2005 were classified according to serogroup, multilocus sequence typing, and outer membrane protein (porA, porB, and fetA) genotyping. Clones were defined as isolates that were indistinguishable according to this characterization. Case data were aggregated to the census tract level and all non-singleton clones were assessed for non-random spatial and temporal clustering using retrospective space-time analyses with a discrete Poisson probability model.ResultsAmong 1,062 geocoded cases with available isolates, 438 unique clones were identified, 78 of which had ≥2 isolates. 702 cases were attributable to non-singleton clones, accounting for 66.0% of all geocoded cases. 32 statistically significant clusters comprised of 107 cases (10.1% of all geocoded cases) were identified. Clusters had the following attributes: included 2 to 11 cases; 1 day to 33 months duration; radius of 0 to 61.7 km; and attack rate of 0.7 to 57.8 cases per 100,000 population. Serogroups represented among the clusters were: B (n = 12 clusters, 45 cases), C (n = 11 clusters, 27 cases), and Y (n = 9 clusters, 35 cases); 20 clusters (62.5%) were caused by serogroups represented in meningococcal vaccines that are commercially available in the United States.ConclusionsAround 10% of meningococcal disease cases in the U.S. could be assigned to a geotemporal cluster. Molecular characterization of isolates, combined with geotemporal analysis, is a useful tool for understanding the spread of virulent meningococcal clones and patterns of transmission in populations.

Genome-Based Characterization of Emergent Invasive Neisseria meningitidis Serogroup Y Isolates in Sweden from 1995 to 2012

“…However, there is also some evidence for differences in the incidence of particular variants at particular times. For example, a study of IMD isolates in the United States from 2000 to 2005 ( 30 ) indicated that the most common clone belonged to serogroup Y and shared the same fine type as the Swedish strain type YI, although it is difficult to assess if this clone is identical to YI in the absence of WGS data. We have shown that the expansion of serogroup Y disease in Sweden was mostly due to the increase of subtype 1 of the previously described strain type YI ( 9 , 12 ).…”

A cluster of invasive meningococcal disease revealed by the characterization of a novel serogroup B meningococcal clone

“…In a US study, 10% of meningococcal disease cases (2000–2005) could be assigned to a geo-temporal cluster (about a third of clusters – serogroup B). Molecular characterization of isolates, combined with geo-temporal analysis, was found useful in detecting the spread of virulent meningococcal clones and transmission patterns [11]. A study from Germany using a combination of molecular fine typing and spatio-temporal analysis revealed that the proportion of IMD cases in spatio-temporal clusters was 4·2% [12].…”

Outbreaks of meningococcal B infection and the 4CMenB vaccine: historical and future perspectives

“…[53]. In Oregon in the mid-1990s, the USA with the same antigenic profile as the Norwegian strains (B:15:P1.7,16) caused the majority of IMD in parts of Washington State and the outbreak had a similar profile to that in Norway -predominantly affecting teenagers and with a high case fatality rate (10%), though with the highest mortality in older adults (aged 55-88) [54,55]. Most recently, in 2013, two college outbreaks occurred in the USA, which prompted the first deployment of the investigational 4CMenB vaccine, the first vaccine capable of eliciting antibody against serogroup B strains used for outbreak control in the USA.…”