Serogroup C Neisseria meningitidis disease epidemiology, seroprevalence, vaccine effectiveness and waning immunity, England, 1998/99 to 2015/16.

Background In 1999, the United Kingdom (UK) was the first country to introduce meningococcal group C (MenC) conjugate vaccination. This vaccination programme has evolved with further understanding, new vaccines and changing disease epidemiology. Aim To characterise MenC disease and population protection against MenC disease in England. Methods Between 1998/99-2015/16, surveillance data from England for laboratory-confirmed MenC cases were collated; using the screening method, we updated vaccine effectiveness (VE) estimates. Typing data and genomes were obtained from the Meningitis Research Foundation Meningococcus Genome Library and PubMLST Neisseria database. Phylogenetic network analysis of MenC cc11 isolates was undertaken. We compared bactericidal antibody assay results using anonymised sera from 2014 to similar data from 1996-1999, 2000-2004 and 2009. Results MenC cases fell from 883 in 1998/99 (1.81/100,000 population) to 42 cases (0.08/100,000 population) in 2015/16. Lower VE over time since vaccination was observed after infant immunisation (p = 0.009) and a single dose at 1-4 years (p = 0.03). After vaccination at 5-18 years, high VE was sustained for ≥ 8 years; 95.0% (95% CI: 76.0- 99.5%). Only 25% (75/299) children aged 1-14 years were seroprotected against MenC disease in 2014. Recent case isolates mostly represented two cc11 strains. Conclusion High quality surveillance has furthered understanding of MenC vaccines and improved schedules, maximising population benefit. The UK programme provides high direct and indirect protection despite low levels of seroprotection in some age groups. High-resolution characterisation supports ongoing surveillance of distinct MenC cc11 lineages

Emergence of Epidemic Neisseria meningitidis Serogroup X Meningitis in Togo and Burkina Faso

Serogroup X meningococci (NmX) historically have caused sporadic and clustered meningitis cases in sub-Saharan Africa. To study recent NmX epidemiology, we analyzed data from population-based, sentinel and passive surveillance, and outbreak investigations of bacterial meningitis in Togo and Burkina Faso during 2006–2010. Cerebrospinal fluid specimens were analyzed by PCR. In Togo during 2006–2009, NmX accounted for 16% of the 702 confirmed bacterial meningitis cases. Kozah district experienced an NmX outbreak in March 2007 with an NmX seasonal cumulative incidence of 33/100,000. In Burkina Faso during 2007–2010, NmX accounted for 7% of the 778 confirmed bacterial meningitis cases, with an increase from 2009 to 2010 (4% to 35% of all confirmed cases, respectively). In 2010, NmX epidemics occurred in northern and central regions of Burkina Faso; the highest district cumulative incidence of NmX was estimated as 130/100,000 during March–April. Although limited to a few districts, we have documented NmX meningitis epidemics occurring with a seasonal incidence previously only reported in the meningitis belt for NmW135 and NmA, which argues for development of an NmX vaccine

Epidemiology, Molecular Characterization and Antibiotic Resistance of Neisseria meningitidis from Patients ≤15 Years in Manhiça, Rural Mozambique

BACKGROUND: The epidemiology of meningococcal disease in Mozambique and other African countries located outside the "meningitis belt" remains widely unknown. With the event of upcoming vaccines microbiological and epidemiological information is urgently needed. METHODS: Prospective surveillance for invasive bacterial infections was conducted at the Manhiça District hospital (rural Mozambique) among hospitalized children below 15 years of age. Available Neisseria meningitidis isolates were serogrouped and characterized by Multilocus Sequence Typing (MLST). Antibiotic resistance was also determined. RESULTS: Between 1998 and 2008, sixty-three cases of confirmed meningococcal disease (36 meningitis, 26 sepsis and 1 conjunctivitis) were identified among hospitalized children. The average incidence rate of meningococcal disease was 11.6/100,000 (8/100,000 for meningitis and 3.7/100,000 for meningococcemia, respectively). There was a significant rise on the number of meningococcal disease cases in 2005-2006 that was sustained till the end of the surveillance period. Serogroup was determined for 43 of the 63 meningococcal disease cases: 38 serogroup W-135, 3 serogroup A and 2 serogroup Y. ST-11 was the most predominant sequence type and strongly associated with serogroup W-135. Two of the three serogroup A isolates were ST-1, and both serogroup Y isolates were ST-175. N. meningitidis remained highly susceptible to all antibiotics used for treatment in the country, although the presence of isolates presenting intermediate resistance to penicillin advocates for continued surveillance. CONCLUSIONS: Our data show a high rate of meningococcal disease in Manhiça, Mozambique, mainly caused by serogroup W-135 ST-11 strains, and advocates for the implementation of a vaccination strategy covering serogroup W-135 meningococci in the country

The everchanging epidemiology of meningococcal disease worldwide and the potential for prevention through vaccination.

Neisseria meningitidis is a major cause of bacterial meningitis and septicaemia worldwide and is associated with high case fatality rates and serious life-long complications among survivors. Twelve serogroups are recognised, of which six (A, B, C, W, X and Y) are responsible for nearly all cases of invasive meningococcal disease (IMD). The incidence of IMD and responsible serogroups vary widely both geographically and over time. For the first time, effective vaccines against all these serogroups are available or nearing licensure. Over the past two decades, IMD incidence has been declining across most parts of the world through a combination of successful meningococcal immunisation programmes and secular trends. The introduction of meningococcal C conjugate vaccines in the early 2000s was associated with rapid declines in meningococcal C disease, whilst implementation of a meningococcal A conjugate vaccine across the African meningitis belt led to near-elimination of meningococcal A disease. Consequently, other serogroups have become more important causes of IMD. In particular, the emergence of a hypervirulent meningococcal group W clone has led many countries to shift from monovalent meningococcal C to quadrivalent ACWY conjugate vaccines in their national immunisation programmes. Additionally, the recent licensure of two protein-based, broad-spectrum meningococcal B vaccines finally provides protection against the most common group responsible for childhood IMD across Europe and Australia. This review describes global IMD epidemiology across each continent and trends over time, the serogroups responsible for IMD, the impact of meningococcal immunisation programmes and future needs to eliminate this devastating disease

Radiative energy loss in an opaque medium

Dans le but de comprendre les résultats des expériences sur le plasma de quarks et de gluons telle qu'ALICE au LHC du CERN, il est important d'avoir des modèles précis pour étudier le comportement des particules élémentaires dans ce milieu exotique. Ce travail de thèse s'inscrit dans l'optique de l'évaluation de la perte d'énergie d'une particule ultrarelativiste se propageant dans un milieu dense. La perte d'énergie par rayonnement étant un processus caractérisé par un temps appelé temps de formation, on peut se demander si celle-ci est modifiée lorsque le gluon produit interagit luimême dans le milieu pendant ce même temps. Du point de vue microscopique, on souhaite regarder la situation dans laquelle le libre parcours moyen dans le milieu est plus court que le temps de formation du gluon principal. Ainsi, dans cette fenêtre en temps, la paire quark-gluon continuant d'interagir dans le milieu, on s'attend à la possibilité d'émettre d'autres gluons, secondaires, de plus basse énergie et pouvant avoir une influence sur la perte d'énergie du quark elle-même. Pour regarder cela, on propose un formalisme effectif permettant d'inclure dans la propagation du quark ou du gluon principal ce rayonnement secondaire dans une limite ultrarelativiste et pour des rayonnements dont l'énergie est négligeable devant celle de la paire principale. On montre que l'effet de ce rayonnement secondaire est de réduire le temps de formation du gluon primaire à des valeurs de l'ordre du libre parcours moyen impliquant une diminution du spectre de rayonnement et de la perte d'énergie du parton émetteur.In order to understand the results of experiments on quark-gluon plasma such as ALICE at LHC at CERN, it is important to have accurate models to study the behavior of elementary particles in this kind of exotic medium. This thesis work is incorporated within the framework of radiative energy loss of an ultrarelativistic particle propagating in a dense medium. The radiative energy loss is a process characterized by a time called formation time so one can wonder if this energy loss is modified when the emitted gluon itself interacts in the medium during its formation. From the microscopic viewpoint, we want to look at the situation in which the mean free path in the medium is shorter than the formation time of the primary gluon. Thus, in this window of time, the quark-gluon pair being formed continues to interact in the medium with the possibility of emitting other gluons, called secondary ones, at lower energies and which could have an effect on the energy loss of the quark itself. To investigate this, we propose an effective formalism allowing us to include these secondary radiations in the propagation of the main quark or gluon in an ultrarelativistic limit and for radiations whose energy is negligible compared to the one of the principal pair. It will be shown that these secondary radiations reduce the formation time of the primary gluon to values of the order of the mean free path implying a decrease for the radiation spectrum and for the energy loss of the emitting parton

Etude des possibilites de mesure des parametres oceaniques avec un radar en onde de ciel

SIGLEAvailable from INIST (FR), Document Supply Service, under shelf-number : TD 20395 / INIST-CNRS - Institut de l'Information Scientifique et TechniqueFRFranc

FILCOH - A Novel Technique to Reduce Ground Clutter Echoes in Precipitation Radars Operating in Multiple PRT

International audienceFILtering by COHerence (FILCOH) is a novel technique for mitigating ground clutter echoes of weather radar, particularly those transmitting in multiple pulse repetition time (PRT) schemes. FILCOH takes advantage of the differences in correlation time for separating rain and ground echoes. In short, the longest time-lag coefficients of the autocorrelation function are used to estimate the ground clutter contribution which is then subtracted from the shortest lag coefficients before the extraction of the meteorological parameters using the conventional estimators. The initial results are obtained for uniform PRT data provided by the Degreane Horizon wind profiler radar. The analysis illustrates the behavior of FILCOH filtering and its high performance in such cases. The simulation results are then presented for 2- and 3-PRT pulse schemes using standard PRT ratios. For the 2-PRT scheme, FILCOH filters out the ground clutter echoes up to a clutter to signal ratio (CSR) of 65 dB for the received power and up to 45 and 60 dB for the radial velocity and spectrum width, respectively. For the 3-PRT scheme, ground clutter filtering is effective up to CSR = 45 dB for the received power and up to CSR = 35 dB for radial velocity and spectrum width. These results are confirmed by 3-PRT real data issued from the French X- and C-band radars. The observed performances are, however, a little less than those of the simulation since we observed a maximum 40-dB attenuation of the ground clutter echoes of the studied rain events