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1.
Trans R Soc Trop Med Hyg ; 106(5): 289-97, 2012 May.
Artículo en Inglés | MEDLINE | ID: mdl-22341686

RESUMEN

To investigate the potential herd immunity effect of MenAfriVac, a new conjugate vaccine against serogroup A Neisseria meningitidis, a multiple cross-sectional carriage study was conducted in three districts in Burkina Faso in 2009, yielding a total of 20 326 oropharyngeal samples. A major challenge was the harmonisation of operational procedures and ensuring the reliability of results. Here we describe the laboratory quality control (QC) system that was implemented. Laboratory analysis performed by three local laboratories included colony morphology assessment, oxidase test, Gram stain, ß-galactosidase activity using o-nitrophenyl-ß-galactopyranoside (ONPG), γ-glutamyl transferase (GGT) activity and slide agglutination serogrouping. Internal QC was performed on media, reagents, laboratory equipment and field conditions. Confirmation of results and molecular characterisation was performed at the Norwegian Institute of Public Health (Oslo, Norway). External QC was performed on 3% of specimens where no colonies morphologically resembling N. meningitidis had been identified and on 10% of non-ONPG-/GGT+ isolates. The QC system was a critical element: it identified logistical and operational problems in real time and ensured accuracy of the final data. The overall N. meningitidis carriage prevalence (3.98%) was probably slightly underestimated and the calculated true prevalence was 4.48%. The components of the presented QC system can easily be implemented in any other laboratory study.


Asunto(s)
Portador Sano/inmunología , Meningitis Meningocócica/inmunología , Vacunas Meningococicas/farmacología , Neisseria meningitidis/inmunología , Burkina Faso/epidemiología , Estudios Transversales , Humanos , Meningitis Meningocócica/prevención & control , Neisseria meningitidis/clasificación , Neisseria meningitidis/aislamiento & purificación , Prevalencia , Control de Calidad , Reproducibilidad de los Resultados , Vacunas Conjugadas/farmacología
2.
Clin Vaccine Immunol ; 18(3): 435-43, 2011 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-21228139

RESUMEN

The serogroup A meningococcal conjugate vaccine MenAfriVac has the potential to confer herd immunity by reducing carriage prevalence of epidemic strains. To better understand this phenomenon, we initiated a meningococcal carriage study to determine the baseline carriage rate and serogroup distribution before vaccine introduction in the 1- to 29-year old population in Burkina Faso, the group chosen for the first introduction of the vaccine. A multiple cross-sectional carriage study was conducted in one urban and two rural districts in Burkina Faso in 2009. Every 3 months, oropharyngeal samples were collected from >5,000 randomly selected individuals within a 4-week period. Isolation and identification of the meningococci from 20,326 samples were performed by national laboratories in Burkina Faso. Confirmation and further strain characterization, including genogrouping, multilocus sequence typing, and porA-fetA sequencing, were performed in Norway. The overall carriage prevalence for meningococci was 3.98%; the highest prevalence was among the 15- to 19-year-olds for males and among the 10- to 14-year-olds for females. Serogroup Y dominated (2.28%), followed by serogroups X (0.44%), A (0.39%), and W135 (0.34%). Carriage prevalence was the highest in the rural districts and in the dry season, but serogroup distribution also varied by district. A total of 29 sequence types (STs) and 51 porA-fetA combinations were identified. The dominant clone was serogroup Y, ST-4375, P1.5-1,2-2/F5-8, belonging to the ST-23 complex (47%). All serogroup A isolates were ST-2859 of the ST-5 complex with P1.20,9/F3-1. This study forms a solid basis for evaluating the impact of MenAfriVac introduction on serogroup A carriage.


Asunto(s)
Portador Sano/epidemiología , Infecciones Meningocócicas/epidemiología , Neisseria meningitidis/clasificación , Neisseria meningitidis/aislamiento & purificación , Adolescente , Adulto , Técnicas de Tipificación Bacteriana , Burkina Faso/epidemiología , Portador Sano/microbiología , Niño , Preescolar , Estudios Transversales , Femenino , Genotipo , Humanos , Lactante , Masculino , Infecciones Meningocócicas/microbiología , Vacunas Meningococicas/administración & dosificación , Vacunas Meningococicas/inmunología , Tipificación Molecular , Tipificación de Secuencias Multilocus , Prevalencia , Población Rural , Serotipificación , Población Urbana , Vacunas Conjugadas/administración & dosificación , Vacunas Conjugadas/inmunología , Adulto Joven
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