[Changing epidemiology of meningococcal disease] / Évolution de l'épidémiologie des infections invasives à méningocoques

Changing epidemiology of meningococcal disease. The epidemiology of invasive meningococcal disease (IMD) is characterized by a marked variation in incidence and serogroup distribution by geographical region and over time. Immunization programs against serogroups A, C, W, Y in adolescents in North America or mass vaccination campaigns against serogroup A in Sub-Saharan Africa reduced the disease burden in these affected areas. In Europe, immunization against serogroup C in several countries has been successful in reducing incidence through direct and indirect effect. In France, surveillance of IMD is based on mandatory notification and strain genetic characterization at the National reference Center for meningococci. Despite its low incidence (between 0.7 and 1.6 cases per 100,000 people), the disease remains of public health concern because it affects mostly young children and the case fatality rate is around 10%. The rates of vaccination coverage for serogroup C vaccines remain insufficient, particularly among adolescents, to induce herd immunity.

Évolution de l'épidémiologie des infections invasives à méningocoques. L'épidémiologie des infections invasives à méningocoques se caractérise par une variation de l'incidence et de la distribution des sérogroupes en fonction des régions géographiques et des années. Des programmes de vaccination des adolescents contre les sérogroupes A, C, W et Y en Amérique du Nord ou des campagnes de vaccination de masse contre le sérogroupe A en Afrique subsaharienne ont réduit le poids de la maladie dans les régions concernées. En Europe, la vaccination contre le méningocoque C dans plusieurs pays a permis de réduire de façon importante l'incidence de la maladie par effets direct et indirect de la vaccination. En France, la surveillance des infections repose sur la déclaration obligatoire et la caractérisation génotypique des méningocoques invasifs au Centre national de référence des méningocoques. Même si l'incidence des infections invasives à méningocoques est basse (entre 0,7 et 1,6 cas pour 100 000 habitants), la maladie reste une préoccupation de santé publique du fait des taux d'incidence élevés chez les jeunes enfants et de la mortalité (10 % en moyenne). Les niveaux de couverture vaccinale contre le méningocoque C restent encore insuffisants, notamment chez les adolescents, pour induire une immunité de groupe.

From tailor-made to ready-to-wear meningococcal B vaccines: longitudinal study of a clonal meningococcal B outbreak.

BACKGROUND: Outer-membrane-vesicle vaccines for meningococcal B outbreaks are complex and time consuming to develop. We studied the use of already available vaccine to control an outbreak caused by a genetically close strain. METHODS: From 2006 to 2009, all individuals younger than 20 years living in the region of Normandy, France, in which an outbreak caused by a B:14:P1.7,16 strain occurred, were eligible to receive MenBvac, a Norwegian vaccine designed 20 years earlier against a strain sharing the same serosubtype (B:15:P1.7,16). The immunogenicity (in a randomly selected cohort of 400 children aged 1-5 years), safety, and epidemiological effect of the vaccination were assessed. FINDINGS: 26,014 individuals were eligible to receive the vaccine. Shortage of vaccine production prompted start of the campaign in the highest incidence groups (1-5 years). 16,709 (64%) received a complete vaccination schedule of whom 13,589 (81%) received a 2+1 dose schedule (week 0, week 6, and month 8). At 6 weeks after the third dose, of 235 vaccinees for whom samples were available, 206 (88%) had a seroresponse, and 108 (56 %) of 193 had a seroresponse at 15 months. These results were similar to those described for tailor-made vaccines and their homologous strain. Only previously described adverse effects occurred. The incidence of B:14:P1.7,16 cases decreased significantly in the vaccine targeted population after the primary vaccination period (from 31·6 per 100,000 to 5·9 per 100,000; p=0·001). INTERPRETATION: The ready-to-wear approach is reliable if epidemic and vaccine strains are genetically close. Other meningococcal B clonal outbreaks might benefit from this strategy; and previously described outer-membrane-vesicle vaccines can be effective against various strains. FUNDING: French Ministry of Health.

Co-circulation of multiple measles virus genotypes during an epidemic in France in 2008.

In 2008, measles reappeared in France in a series of outbreaks. During this period, 604 measles cases were reported to a routine surveillance system and 305 (50%) of these cases were then confirmed in the laboratory. To understand better the current epidemiological situation and the circulation of different measles strains, a phylogenetic characterization of 113 (19%) of the measles cases from these outbreaks was performed. All measles cases met the WHO clinical criteria and were confirmed either by laboratory detection of measles-specific IgM and/or by detection of the virus genome by polymerase chain reaction (PCR) and viral isolation. PCR products generated from blood, oral fluid, urine, or nasopharyngeal-swab samples were sequenced for molecular epidemiology studies. Phylogenetic analysis showed a co-circulation of genotypes D4 and D5 during the first measles outbreak in the city of Reims in early 2008. Over the course of the year, the A, B3.2, D8, and D9 genotypes also appeared. The data from this study show the simultaneous circulation of several measles genotypes in France and describe genotypes D8 and D9 for the first time in this country. The data also suggest that there are still many pockets of unvaccinated individuals helping to maintain the circulation of measles virus in the population. Phylogenetic studies allowed the corroboration of epidemiologic links and showed that nosocomial transmission can create significant risk for measles dissemination. Finally, the pattern of changes in viral genotypes during 2008 suggests a regular introduction of measles strains from abroad.

Evidence of Bordetella pertussis infection in adults presenting with persistent cough in a french area with very high whole-cell vaccine coverage.

Although France has had a vaccination program for 40 years, since 1990, an increase in whooping cough cases with parent-infant transmission has been observed. This study prospectively assessed the frequency of Bordetella pertussis infection in adults who consulted general practitioners for a persistent cough without an evident diagnosis. Among 217 patients, 70 (32%) confirmed whooping cough cases were identified. One case was culture positive, 36 were polymerase chain reaction positive, and 40 had increases or decreases of > or =2-fold in anti-pertussis toxin IgG titer between serum samples collected during the acute and convalescent phases. The median duration of cough in confirmed cases was 49 days (range, 13-123 days). Of the patients, 60% reported vaccination, and 33% reported whooping cough in infancy. Pertussis should be considered for diagnosis of acute and chronic cough in adults. Future studies should evaluate the public health interest of booster doses of pertussis vaccine in adults.