RESUMEN
Antimicrobial resistance poses a significant challenge to public health globally, leading to increased morbidity and mortality. AMR surveillance involves the systematic collection, analysis, and interpretation of data on the occurrence and distribution of AMR in humans, animals, and the environment for action. The West African Health Organization, part of the Economic Community of West African States (ECOWAS), is committed to addressing AMR in the region. This paper examines the status of AMR surveillance in ECOWAS countries using available WHO data from the TrACSS survey and GLASS enrollments. The analysis reveals that while progress has been made, significant challenges remain. Twelve of the fifteen ECOWAS countries are enrolled in GLASS, and ten have developed national action plans (NAPs) for AMR. However, there is a need to ensure all countries fully implement their NAPs, continue reporting to GLASS, and use the data for evidence-based actions and decision making. Surveillance systems for AMR and antimicrobial consumption/use vary across countries with some demonstrating limited capacity. All countries, except Cabo Verde, reported having a reference laboratory for AMR testing. Strengthening laboratory capabilities, data management and use, and multisectoral coordination are crucial for effective AMR surveillance and response. Based on the findings and the regional context, it is essential to prioritize capacity building, data utilization, and the adoption of standardized guidelines for AMR surveillance. Collaboration among ECOWAS countries, the WAHO, and international partners is essential to address AMR comprehensively. Ensuring a consistent supply of essential antimicrobial medications and reagents is vital.
RESUMEN
OBJECTIVE: To investigate potential risk factors for acquisition in seven countries of the meningitis belt. METHODS: Households were followed up every 2 weeks for 2 months, then monthly for a further 4 months. Pharyngeal swabs were collected from all available household members at each visit and questionnaires completed. Risks of acquisition over the whole study period and for each visit were analysed by a series of logistic regressions. RESULTS: Over the course of the study, acquisition was higher in: (i) 5-to 14-year olds, as compared with those 30 years or older (OR 3.6, 95% CI 1.4-9.9); (ii) smokers (OR 3.6, 95% CI 0.98-13); and (iii) those exposed to wood smoke at home (OR 2.6 95% CI 1.3-5.6). The risk of acquisition from one visit to the next was higher in those reporting a sore throat during the dry season (OR 3.7, 95% CI 2.0-6.7) and lower in those reporting antibiotic use (OR 0.17, 95% CI 0.03-0.56). CONCLUSIONS: Acquisition of meningococcal carriage peaked in school age children. Recent symptoms of sore throat during the dry season, but not during the rainy season, were associated with a higher risk of acquisition. Upper respiratory tract infections may be an important driver of epidemics in the meningitis belt.
OBJECTIF: Investiguer les facteurs de risque potentiels d'acquisition dans sept pays de la ceinture de la méningite. MÉTHODES: Des ménages ont été suivis toutes les deux semaines pendant deux mois, puis tous les mois pendant quatre mois. Des prélèvements pharyngés sur écouvillons ont été collectés auprès de tous les membres disponibles du ménage à chaque visite et des questionnaires ont été remplis. Les risques d'acquisition sur l'ensemble de la période d'étude et pour chaque visite ont été analysés par une série de régressions logistiques. RÉSULTATS: Au cours de l'étude, l'acquisition a été plus élevée chez: (i) les 5-14 ans, par rapport à ceux âgés de 30 ans ou plus (OR = 3,6; IC95%: 1,4-9,9); (ii) les fumeurs (OR = 3,6; IC95%: 0,98-13); et (iii) les personnes exposées à la fumée de bois à la maison (OR = 2,6; IC95%: 1,3-5,6). Le risque d'acquisition d'une visite à l'autre était plus élevé chez les personnes signalant un mal de gorge pendant la saison sèche (OR = 3,7; IC95%: 2,0-6,7) et plus faible chez celles signalant une utilisation d'antibiotique (OR = 0,17; IC95%: 0,03-0,56). CONCLUSIONS: L'acquisition du portage du méningocoque a culminé chez les enfants d'âge scolaire. Les symptômes récents de maux de gorge pendant la saison sèche, mais pas pendant la saison des pluies, étaient associés à un risque d'acquisition plus élevé. Les infections des voies respiratoires supérieures pourraient être un facteur important d'épidémies dans la ceinture de la méningite.
Asunto(s)
Portador Sano/microbiología , Meningitis Meningocócica/etiología , Infecciones del Sistema Respiratorio/complicaciones , Estaciones del Año , Adolescente , Adulto , África del Sur del Sahara/epidemiología , Anciano , Antibacterianos/uso terapéutico , Niño , Preescolar , Estudios Transversales , Femenino , Humanos , Lactante , Modelos Logísticos , Masculino , Meningitis Meningocócica/microbiología , Persona de Mediana Edad , Neisseria meningitidis Serogrupo A/crecimiento & desarrollo , Faringitis , Factores de Riesgo , Humo/efectos adversos , Fumar/efectos adversos , Adulto JovenRESUMEN
Improved methods for the detection and characterization of carried Neisseria meningitidis isolates are needed. We evaluated a multiplex PCR algorithm for the detection of a variety of carriage strains in the meningitis belt. To further improve the sensitivity and specificity of the existing PCR assays, primers for gel-based PCR assays (sodC, H, Z) and primers/probe for real-time quantitative PCR (qPCR) assays (porA, cnl, sodC, H, E, Z) were modified or created using Primer Express software. Optimized multiplex PCR assays were tested on 247 well-characterised carriage isolates from six countries of the African meningitis belt. The PCR algorithm developed enabled the detection of N. meningitidis species using gel-based and real-time multiplex PCR targeting porA, sodC, cnl and characterization of capsule genes through sequential multiplex PCR assays for genogroups (A, W, X, then B, C, Y and finally H, E and Z). Targeting both porA and sodC genes together allowed the detection of meningococci with a sensitivity of 96% and 89% and a specificity of 78% and 67%, for qPCR and gel-based PCR respectively. The sensitivity and specificity ranges for capsular genogrouping of N. meningitidis are 67% - 100% and 98%-100% respectively for gel-based PCR and 90%-100% and 99%-100% for qPCR. We developed a PCR algorithm that allows simple, rapid and systematic detection and characterisation of most major and minor N. meningitidis capsular groups, including uncommon capsular groups (H, E, Z).
Asunto(s)
Algoritmos , Meningitis Meningocócica , Reacción en Cadena de la Polimerasa Multiplex/métodos , Neisseria meningitidis/genética , Porinas/genética , Superóxido Dismutasa/genética , Femenino , Humanos , Masculino , Malí/epidemiología , Meningitis Meningocócica/diagnóstico , Meningitis Meningocócica/epidemiología , Meningitis Meningocócica/genética , Neisseria meningitidis/aislamiento & purificación , Sensibilidad y EspecificidadRESUMEN
OBJECTIVES: Carriers of Neisseria meningitidis are a key source of transmission. In the African meningitis belt, where risk of meningococcal disease is highest, a greater understanding of meningococcal carriage dynamics is needed. METHODS: We randomly selected an age-stratified sample of 400 residents from 116 households in Bamako, Mali, and collected pharyngeal swabs in May 2010. A month later, we enrolled all 202 residents of 20 of these households (6 with known carriers) and collected swabs monthly for 6 months prior to MenAfriVac vaccine introduction and returned 10 months later to collect swabs monthly for 3 months. We used standard bacteriological methods to identify N. meningitidis carriers and fit hidden Markov models to assess acquisition and clearance overall and by sex and age. RESULTS: During the cross-sectional study 5.0% of individuals (20/400) were carriers. During the longitudinal study, 73 carriage events were identified from 1422 swabs analyzed, and 16.3% of individuals (33/202) were identified as carriers at least once. The majority of isolates were non-groupable; no serogroup A carriers were identified. CONCLUSIONS: Our results suggest that the duration of carriage with any N. meningitidis averages 2.9 months and that males and children acquire and lose carriage more frequently in an urban setting in Mali. Our study informed the design of a larger study implemented in seven countries of the African meningitis belt.
Asunto(s)
Portador Sano/epidemiología , Portador Sano/microbiología , Infecciones Meningocócicas/epidemiología , Neisseria meningitidis/aislamiento & purificación , Adolescente , Adulto , Niño , Preescolar , Estudios Transversales , Composición Familiar , Femenino , Humanos , Lactante , Estudios Longitudinales , Masculino , Malí/epidemiología , Tamizaje Masivo , Meningitis Meningocócica/epidemiología , Infecciones Meningocócicas/transmisión , Neisseria meningitidis Serogrupo A/aislamiento & purificación , Faringe/microbiología , Proyectos Piloto , Adulto JovenRESUMEN
BACKGROUND: Serum bactericidal antibody titres that correlate with protection against invasive meningococcal disease have been characterised. However, titres that are associated with protection against acquisition of pharyngeal carriage of Neisseria meningitidis are not known. METHODS: Sera were obtained from the members of a household in seven countries of the African meningitis belt in which a pharyngeal carrier of N. meningitidis had been identified during a cross-sectional survey. Serum bactericidal antibody titres at baseline were compared between individuals in the household of the carrier who became a carrier of a meningococcus of the same genogroup during six months of subsequent follow-up and household members who did not become a carrier of a meningococcus of this genogroup during this period. RESULTS: Serum bacterial antibody titres were significantly higher in carriers of a serogroup W or Y meningococcus at the time of recruitment than in those who were not a carrier of N. meningitidis of the same genogroup. Serum bactericidal antibody titres to a strain of N. meningitis of the same genogroup as the index cases were no different in individuals who acquired carriage with a meningococcus of the same genogroup as the index case than in those who did not become a carrier during six months of follow-up. CONCLUSION: Serum bacterial antibody titres to N. meningitidis of genogroup W or Y in the range of those acquired by natural exposure to meningococci of these genogroups, or with cross-reactive bacteria, are not associated with protection against acquisition of carriage with meningococci of either of these genogroups.
Asunto(s)
Enfermedades Endémicas , Meningitis Meningocócica/microbiología , Neisseria meningitidis Serogrupo W-135/inmunología , Neisseria meningitidis Serogrupo Y/inmunología , Faringe/microbiología , Anticuerpos Antibacterianos/sangre , Portador Sano , Estudios Transversales , Femenino , Humanos , Masculino , Meningitis Meningocócica/epidemiología , Meningitis Meningocócica/inmunología , Meningitis Meningocócica/prevención & control , Factores Protectores , Factores de Riesgo , Vacunación , Adulto JovenRESUMEN
BACKGROUND: Serogroup A Neisseria meningitidis (NmA) was the cause of the 2011 meningitis epidemics in Chad. This bacterium, often carried asymptomatically, is considered to be an "accidental pathogen"; however, the transition from carriage to disease phenotype remains poorly understood. This study examined the role genetic diversity might play in this transition by comparing genomes from geographically and temporally matched invasive and carried NmA isolates. RESULTS: All 23 NmA isolates belonged to the ST-5 clonal complex (cc5). Ribosomal MLST comparison with other publically available NmA:cc5 showed that isolates were closely related, although those from Chad formed two distinct branches and did not cluster with other NmA, based on their MLST profile, geographical and temporal location. Whole genome MLST (wgMLST) comparison identified 242 variable genes among all Chadian isolates and clustered them into three distinct phylogenetic groups (Clusters 1, 2, and 3): no systematic clustering by disease or carriage source was observed. There was a significant difference (p = 0.0070) between the mean age of the individuals from which isolates from Cluster 1 and Cluster 2 were obtained, irrespective of whether the person was a case or a carrier. CONCLUSIONS: Whole genome sequencing provided high-resolution characterization of the genetic diversity of these closely related NmA isolates. The invasive meningococcal isolates obtained during the epidemic were not homogeneous; rather, a variety of closely related but distinct clones were circulating in the human population with some clones preferentially colonizing specific age groups, reflecting a potential age-related niche adaptation. Systematic genetic differences were not identified between carriage and disease isolates consistent with invasive meningococcal disease being a multi-factorial event resulting from changes in host-pathogen interactions along with the bacterium.
Asunto(s)
Enfermedades Asintomáticas/epidemiología , Epidemias , Genómica , Meningitis Meningocócica/epidemiología , Neisseria meningitidis/genética , Neisseria meningitidis/fisiología , Serogrupo , Adolescente , Adulto , Chad/epidemiología , Niño , Preescolar , Análisis por Conglomerados , Femenino , Humanos , Lactante , Masculino , Secuenciación Completa del Genoma , Adulto JovenRESUMEN
Conventional methods for detecting pharyngeal carriage of Neisseria meningitidis are complex. There is a need for simpler methods with improved performance. We have investigated two alternative approaches. Three pharyngeal swabs were collected from 999 pupils aged 10 to 18 years in The Gambia. Carriage of N. meningitidis was investigated by using three different methods: (i) plating on Thayer-Martin selective medium and testing by conventional microbiological methods followed by PCR testing; (ii) seeding in Todd-Hewitt broth (THB) and, after culture overnight, testing by PCR; and (iii) compression of the swab on filter paper and, after DNA concentration, testing by PCR. PCR after culture in THB was more than twice as sensitive as conventional methods in detecting N. meningitidis (13.2% versus 5.7%; P < 0.0001). PCR after DNA extraction from filter paper had a sensitivity similar to that of conventional methods (4.9% versus 5.7%; P = 0.33). Capsular genogroups detected by broth culture were genogroups W (21 isolates), B (12 isolates), Y (8 isolates), E (3 isolates), and X (2 isolates), and 68 meningococci had the capsule-null intergenic region. The distributions of genogroups and of capsule-null organisms were similar with each of the three methods. The carriage density in samples extracted from filter paper ranged from 1 to 25,000 DNA copies. PCR of broth cultures grown overnight doubled the yield of N. meningitidis carriage isolates compared with conventional methods. This approach could improve the efficiency of carriage studies. Collection on filter paper followed by quantitative PCR could be useful for density measurement and for carriage studies in areas with limited resources.
Asunto(s)
Carga Bacteriana/métodos , Portador Sano/diagnóstico , Infecciones Meningocócicas/diagnóstico , Neisseria meningitidis/aislamiento & purificación , Faringe/microbiología , Reacción en Cadena de la Polimerasa/métodos , Adolescente , Niño , Estudios Transversales , Medios de Cultivo/química , Femenino , Gambia , Humanos , Masculino , Sensibilidad y EspecificidadRESUMEN
[This corrects the article DOI: 10.1371/journal.pone.0147928.].
RESUMEN
OBJECTIVES: Neisseria meningitidis, together with the non-pathogenic Neisseria species (NPNs), are members of the complex microbiota of the human pharynx. This paper investigates the influence of NPNs on the epidemiology of meningococcal infection. METHODS: Neisseria isolates were collected during 18 surveys conducted in six countries in the African meningitis belt between 2010 and 2012 and characterized at the rplF locus to determine species and at the variable region of the fetA antigen gene. Prevalence and risk factors for carriage were analyzed. RESULTS: A total of 4694 isolates of Neisseria were obtained from 46,034 pharyngeal swabs, a carriage prevalence of 10.2% (95% CI, 9.8-10.5). Five Neisseria species were identified, the most prevalent NPN being Neisseria lactamica. Six hundred and thirty-six combinations of rplF/fetA_VR alleles were identified, each defined as a Neisseria strain type. There was an inverse relationship between carriage of N. meningitidis and of NPNs by age group, gender and season, whereas carriage of both N. meningitidis and NPNs was negatively associated with a recent history of meningococcal vaccination. CONCLUSION: Variations in the prevalence of NPNs by time, place and genetic type may contribute to the particular epidemiology of meningococcal disease in the African meningitis belt.
Asunto(s)
Portador Sano/epidemiología , Meningitis Meningocócica/epidemiología , Infecciones Meningocócicas/epidemiología , Neisseria meningitidis/aislamiento & purificación , Neisseria/aislamiento & purificación , Faringe/microbiología , Adolescente , Adulto , África/epidemiología , Proteínas de la Membrana Bacteriana Externa/genética , Portador Sano/microbiología , Niño , Preescolar , Femenino , Variación Genética/genética , Humanos , Lactante , Masculino , Meningitis Meningocócica/microbiología , Infecciones Meningocócicas/microbiología , Neisseria/clasificación , Prevalencia , Factores de Riesgo , Adulto JovenRESUMEN
The pattern of epidemic meningococcal disease in the African meningitis belt may be influenced by the background level of population immunity but this has been measured infrequently. A standardised enzyme-linked immunosorbent assay (ELISA) for measuring meningococcal serogroup A IgG antibodies was established at five centres within the meningitis belt. Antibody concentrations were then measured in 3930 individuals stratified by age and residence from six countries. Seroprevalence by age was used in a catalytic model to determine the force of infection. Meningococcal serogroup A IgG antibody concentrations were high in each country but showed heterogeneity across the meningitis belt. The geometric mean concentration (GMC) was highest in Ghana (9.09 µg/mL [95% CI 8.29, 9.97]) and lowest in Ethiopia (1.43 µg/mL [95% CI 1.31, 1.57]) on the margins of the belt. The force of infection was lowest in Ethiopia (λ = 0.028). Variables associated with a concentration above the putative protective level of 2 µg/mL were age, urban residence and a history of recent vaccination with a meningococcal vaccine. Prior to vaccination with the serogroup A meningococcal conjugate vaccine, meningococcal serogroup A IgG antibody concentrations were high across the African meningitis belt and yet the region remained susceptible to epidemics.
Asunto(s)
Anticuerpos Antibacterianos/sangre , Epidemias , Inmunoglobulina G/sangre , Meningitis Meningocócica/epidemiología , Meningitis Meningocócica/prevención & control , Vacunas Meningococicas/administración & dosificación , Adolescente , Adulto , África/epidemiología , Anciano , Portador Sano , Niño , Preescolar , Estudios Transversales , Ensayo de Inmunoadsorción Enzimática , Femenino , Humanos , Memoria Inmunológica , Lactante , Masculino , Meningitis Meningocócica/sangre , Meningitis Meningocócica/inmunología , Persona de Mediana Edad , Neisseria meningitidis/clasificación , Neisseria meningitidis/inmunología , Neisseria meningitidis/patogenicidad , Estudios Seroepidemiológicos , Serogrupo , VacunaciónRESUMEN
BACKGROUND: In 2010, mass vaccination with a then-new meningococcal A polysaccharide-tetanus toxoid protein conjugate vaccine (PsA-TT, or MenAfriVac) was undertaken in 1- to 29-year-olds in Bamako, Mali. Whether vaccination with PsA-TT effectively boosts tetanus immunity in a population with heterogeneous baseline tetanus immunity is not known. We assessed the impact of PsA-TT on tetanus toxoid (TT) immunity by quantifying age- and sex-specific immunity prior to and 2 years after introduction. METHODS: Using a household-based, age-stratified design, we randomly selected participants for a prevaccination serological survey in 2010 and a postvaccination survey in 2012. TT immunoglobulin G (IgG) antibodies were quantified and geometric mean concentrations (GMCs) pre- and postvaccination among all age groups targeted for vaccination were compared. The probability of TT IgG levels ≥0.1 IU/mL (indicating short-term protection) and ≥1.0 IU/mL (indicating long-term protection) by age and sex was determined using logistic regression models. RESULTS: Analysis of 793 prevaccination and 800 postvaccination sera indicated that while GMCs were low pre-PsA-TT, significantly higher GMCs in all age-sex strata were observed 2 years after PsA-TT introduction. The percentage with short-term immunity increased from 57.1% to 88.4% (31.3-point increase; 95% confidence interval [CI], 26.6-36.0;, P < .0001) and with long-term immunity increased from 20.0% to 58.5% (38.5-point increase; 95% CI, 33.7-43.3; P < .0001) pre- and postvaccination. CONCLUSIONS: Significantly higher TT immunity was observed among vaccine-targeted age groups up to 2 years after Mali's PsA-TT mass vaccination campaign. Our results, combined with evidence from clinical trials, strongly suggest that conjugate vaccines containing TT such as PsA-TT should be considered bivalent vaccines because of their ability to boost tetanus immunity.
Asunto(s)
Anticuerpos Antibacterianos/sangre , Vacunas Meningococicas/administración & dosificación , Vacunas Meningococicas/inmunología , Antitoxina Tetánica/sangre , Toxoide Tetánico/inmunología , Adolescente , Adulto , Niño , Preescolar , Femenino , Humanos , Inmunoglobulina G/sangre , Lactante , Recién Nacido , Masculino , Malí , Adulto JovenRESUMEN
In 2011, vaccination with a serogroup A meningococcal polysaccharide conjugate vaccine was implemented in 3 of 23 regions in Chad. Cases of meningitis declined dramatically in vaccinated areas, but an epidemic continued in the rest of Chad. In 2012, the remaining Chad population was vaccinated, and the epidemic was halted.
Asunto(s)
Meningitis Meningocócica/prevención & control , Vacunas Meningococicas/administración & dosificación , Vacunación , Adolescente , Adulto , Chad/epidemiología , Niño , Preescolar , Humanos , Lactante , Meningitis Meningocócica/epidemiología , Meningitis Meningocócica/inmunología , Adulto JovenRESUMEN
OBJECTIVE: Detection of meningococcal carriers is key to understanding the epidemiology of Neisseria meningitidis, yet no gold standard has been established. Here, we directly compare two methods for collecting pharyngeal swabs to identify meningococcal carriers. METHODS: We conducted cross-sectional surveys of schoolchildren at multiple sites in Africa to compare swabbing the posterior pharynx behind the uvula (U) to swabbing the posterior pharynx behind the uvula plus one tonsil (T). Swabs were cultured immediately and analyzed using molecular methods. RESULTS: One thousand and six paired swab samples collected from schoolchildren in four countries were analyzed. Prevalence of meningococcal carriage was 6.9% (95% CI: 5.4-8.6%) based on the results from both swabs, but the observed prevalence was lower based on one swab type alone. Prevalence based on the T swab or the U swab alone was similar (5.2% (95% CI: 3.8-6.7%) versus 4.9% (95% CI: 3.6-6.4%) respectively (p=0.6)). The concordance between the two methods was 96.3% and the kappa was 0.61 (95% CI: 0.50-0.73), indicating good agreement. CONCLUSIONS: These two commonly used methods for collecting pharyngeal swabs provide consistent estimates of the prevalence of carriage, but both methods misclassified carriers to some degree, leading to underestimates of the prevalence.
Asunto(s)
Portador Sano/epidemiología , Infecciones Meningocócicas/epidemiología , Neisseria meningitidis/aislamiento & purificación , Manejo de Especímenes/métodos , Adolescente , África Occidental/epidemiología , Niño , Estudios Transversales , Etiopía/epidemiología , Femenino , Humanos , Masculino , Infecciones Meningocócicas/transmisión , Nasofaringe/microbiología , Tonsila Palatina/microbiología , PrevalenciaRESUMEN
For over 100 years, large epidemics of meningococcal meningitis have occurred every few years in areas of the African Sahel and sub-Sahel known as the African meningitis belt. Until recently, the main approach to the control of these epidemics has been reactive vaccination with a polysaccharide vaccine after an outbreak has reached a defined threshold and provision of easy access to effective treatment but this approach has not prevented the occurrence of new epidemics. Meningococcal conjugate vaccines, which can prevent meningococcal carriage and thus interrupt transmission, may be more effective than polysaccharide vaccines at preventing epidemics. Because the majority of African epidemics have been caused by serogroup A meningococci, a serogroup A polysaccharide/tetanus toxoid protein conjugate vaccine (PsA-TT) has recently been developed. Results from an initial evaluation of the impact of this vaccine on meningococcal disease and meningococcal carriage in Burkina Faso have been encouraging. To review how the research agenda for meningococcal disease in Africa has been changed by the advent of PsA-TT and to define a new set of research priorities for study of meningococcal infection in Africa, a meeting of 41 scientists was held in Dakar, Senegal on April 24th and 25th 2012. The research recommendations developed during the course of this meeting are presented in this paper. The need for enhanced surveillance for meningitis in defined populations with good diagnostic facilities in African countries at risk of epidemics was identified as the highest priority. This is needed to determine the duration of protection against serogroup A meningococcal disease provided by PsA-TT and to determine the risk of disease and carriage caused by meningococci of other serogroups. Other research areas given high priority included identification and validation of serological correlates of protection against meningococcal disease and carriage, development of improved methods for detecting carriage and epidemiological studies aimed at determining the reasons underlying the peculiar epidemiology of meningococcal disease in the African meningitis belt. Minutes and working papers from the meeting are provided in supplementary tables and some of the presentations made at the meeting are available on the MenAfriCar consortium website (www.menafricar.org) and on the web site of the Centers for Disease Control (www.cdc.gov).
Asunto(s)
Meningitis Meningocócica/epidemiología , Meningitis Meningocócica/prevención & control , Vacunas Meningococicas/administración & dosificación , Vacunas Meningococicas/inmunología , Neisseria meningitidis Serogrupo A/inmunología , Neisseria meningitidis Serogrupo A/aislamiento & purificación , Investigación Biomédica/tendencias , Burkina Faso/epidemiología , Portador Sano/epidemiología , Portador Sano/microbiología , Portador Sano/prevención & control , Descubrimiento de Drogas/tendencias , Humanos , Meningitis Meningocócica/microbiología , Vacunas Meningococicas/aislamiento & purificación , Senegal , Vacunas Conjugadas/administración & dosificación , Vacunas Conjugadas/inmunología , Vacunas Conjugadas/aislamiento & purificaciónRESUMEN
A critical step in HIV-1 transmission studies is the rapid and accurate identification of epidemiologically linked transmission pairs. To date, this has been accomplished by comparison of polymerase chain reaction (PCR)-amplified nucleotide sequences from potential transmission pairs, which can be cost-prohibitive for use in resource-limited settings. Here we describe a rapid, cost-effective approach to determine transmission linkage based on the heteroduplex mobility assay (HMA), and validate this approach by comparison to nucleotide sequencing. A total of 102 HIV-1-infected Zambian and Rwandan couples, with known linkage, were analyzed by gp41-HMA. A 400-base pair fragment within the envelope gp41 region of the HIV proviral genome was PCR amplified and HMA was applied to both partners' amplicons separately (autologous) and as a mixture (heterologous). If the diversity between gp41 sequences was low (<5%), a homoduplex was observed upon gel electrophoresis and the transmission was characterized as having occurred between partners (linked). If a new heteroduplex formed, within the heterologous migration, the transmission was determined to be unlinked. Initial blind validation of gp-41 HMA demonstrated 90% concordance between HMA and sequencing with 100% concordance in the case of linked transmissions. Following validation, 25 newly infected partners in Kigali and 12 in Lusaka were evaluated prospectively using both HMA and nucleotide sequences. Concordant results were obtained in all but one case (97.3%). The gp41-HMA technique is a reliable and feasible tool to detect linked transmissions in the field. All identified unlinked results should be confirmed by sequence analyses.
Asunto(s)
Proteína gp41 de Envoltorio del VIH/genética , Infecciones por VIH/transmisión , Infecciones por VIH/virología , VIH-1/aislamiento & purificación , Análisis Heterodúplex/métodos , Epidemiología Molecular/métodos , Virología/métodos , Electroforesis , Femenino , VIH-1/genética , Humanos , Masculino , Datos de Secuencia Molecular , Estudios Prospectivos , Análisis de Secuencia de ADNRESUMEN
BACKGROUND: HIV-1 superinfection occurs at varying frequencies in different at risk populations. Though seroincidence is decreased, in the negative partner of HIV-discordant couples after joint testing and counseling in the Zambia Emory HIV Research Project (ZEHRP) cohort, the annual infection rate remains relatively high at 7-8%. Based on sequencing within the gp41 region of each partner's virus, 24% of new infections between 2004 and 2008 were the result of transmission from a non-spousal partner. Since these seroconvertors and their spouses have disparate epidemiologically-unlinked viruses, there is a risk of superinfection within the marriage. We have, therefore, investigated the incidence and viral origin of superinfection in these couples. RESULTS: Superinfection was detected by heteroduplex mobility assay (HMA), degenerate base counting of the gp41 sequence, or by phylogenetic analysis of the longitudinal sequences. It was confirmed by full-length env single genome amplification and phylogenetic analysis. In 22 couples (44 individuals), followed for up to five years, three of the newly infected (initially HIV uninfected) partners became superinfected. In each case superinfection occurred during the first 12 months following initial infection of the negative partner, and in each case the superinfecting virus was derived from a non-spousal partner. In addition, one probable case of intra-couple HIV-1 superinfection was observed in a chronically infected partner at the time of his seroconverting spouse's initial viremia. Extensive recombination within the env gene was observed following superinfection. CONCLUSIONS: In this subtype-C discordant couple cohort, superinfection, during the first year after HIV-1 infection of the previously negative partner, occurred at a rate similar to primary infection (13.6% [95% CI 5.2-34.8] vs 7.8% [7.1-8.6]). While limited intra-couple superinfection may in part reflect continued condom usage within couples, this and our lack of detecting newly superinfected individuals after one year of primary infection raise the possibility that immunological resistance to intra-subtype superinfection may develop over time in subtype C infected individuals.
Asunto(s)
Coinfección/epidemiología , Infecciones por VIH/epidemiología , VIH-1/clasificación , VIH-1/aislamiento & purificación , Adulto , Coinfección/virología , Composición Familiar , Genotipo , Proteína gp41 de Envoltorio del VIH/genética , Infecciones por VIH/virología , VIH-1/genética , Humanos , Incidencia , Masculino , Epidemiología Molecular , Datos de Secuencia Molecular , Análisis de Secuencia de ADN , Factores de Tiempo , ZambiaRESUMEN
BACKGROUND: Mother-to-child transmission (MTCT) of HIV remains a significant problem in resource-limited settings, despite the advent of antiretroviral therapies. Because perturbations in vaginal microbial communities are associated with sexual transmission of HIV, we determined whether perinatal MTCT is associated with the vaginal microbiotas of HIV-infected mothers. METHODS: We conducted a retrospective analysis of cervicovaginal microbiotas by pyrosequencing of bacterial 16S rRNA genes (median 350 sequences per sample) from 10 transmitters and 54 nontransmitters during a perinatal MTCT prevention clinical trial of azidothymidine and the microbicide benzalkonium chloride. Logistic regression was performed adjusting for multiple covariates, including CD4(+) T-cell numbers and treatment group, to correlate abundances of microbial taxa with perinatal MTCT. RESULTS: The vaginal microbiotas of these subjects were dominated by several lactobacilli species, although a subset of subjects was colonized by diverse anaerobic species. MTCT of HIV was associated with significantly greater relative abundances of several groups of microorganisms. Most notably, among the abundant bacterial species, Gardnerella vaginalis was significantly enriched in cases of antepartum transmission, compared with nontransmission (odds ratio 1.7; P = 0.004). Neither azidothymidine nor benzalkonium chloride treatment was associated with shifts in microbial distributions compared with the placebo control group. CONCLUSIONS: These data suggest that alterations in vaginal microbial communities are associated with an increased risk for perinatal MTCT, consistent with results with horizontal transmission of HIV. Therefore, determining the mucosal features associated with alterations in vaginal microbial communities may guide efforts to modulate the risk for HIV MTCT.