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Search Results: 1 - 10 of 316773 matches for " Francisco J Luquero "
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Prognostic Accuracy of WHO Growth Standards to Predict Mortality in a Large-Scale Nutritional Program in Niger
Nathanael Lapidus,Francisco J Luquero,Valérie Gaboulaud,Susan Shepherd,Rebecca F Grais
PLOS Medicine , 2009, DOI: 10.1371/journal.pmed.1000039
Abstract: Background Important differences exist in the diagnosis of malnutrition when comparing the 2006 World Health Organization (WHO) Child Growth Standards and the 1977 National Center for Health Statistics (NCHS) reference. However, their relationship with mortality has not been studied. Here, we assessed the accuracy of the WHO standards and the NCHS reference in predicting death in a population of malnourished children in a large nutritional program in Niger. Methods and Findings We analyzed data from 64,484 children aged 6–59 mo admitted with malnutrition (<80% weight-for-height percentage of the median [WH]% [NCHS] and/or mid-upper arm circumference [MUAC] <110 mm and/or presence of edema) in 2006 into the Médecins Sans Frontières (MSF) nutritional program in Maradi, Niger. Sensitivity and specificity of weight-for-height in terms of Z score (WHZ) and WH% for both WHO standards and NCHS reference were calculated using mortality as the gold standard. Sensitivity and specificity of MUAC were also calculated. The receiver operating characteristic (ROC) curve was traced for these cutoffs and its area under curve (AUC) estimated. In predicting mortality, WHZ (NCHS) and WH% (NCHS) showed AUC values of 0.63 (95% confidence interval [CI] 0.60–0.66) and 0.71 (CI 0.68–0.74), respectively. WHZ (WHO) and WH% (WHO) appeared to provide higher accuracy with AUC values of 0.76 (CI 0.75–0.80) and 0.77 (CI 0.75–0.80), respectively. The relationship between MUAC and mortality risk appeared to be relatively weak, with AUC = 0.63 (CI 0.60–0.67). Analyses stratified by sex and age yielded similar results. Conclusions These results suggest that in this population of children being treated for malnutrition, WH indicators calculated using WHO standards were more accurate for predicting mortality risk than those calculated using the NCHS reference. The findings are valid for a population of already malnourished children and are not necessarily generalizable to a population of children being screened for malnutrition. Future work is needed to assess which criteria are best for admission purposes to identify children most likely to benefit from therapeutic or supplementary feeding programs.
Learning lessons from field surveys in humanitarian contexts: a case study of field surveys conducted in North Kivu, DRC 2006-2008
Rebecca F Grais, Francisco J Luquero, Emmanuel Grellety, Heloise Pham, Benjamin Coghlan, Pierre Salignon
Conflict and Health , 2009, DOI: 10.1186/1752-1505-3-8
Abstract: In media and agency reports on complex emergencies, an estimate of the number of people who have died, the prevalence of childhood malnutrition and other key health indicators are often quoted. Although a discriminating reader may understand that these are estimates, we rarely question how or from where these numbers come. In most cases, estimates are obtained by means of field surveys which are subject to a number of limitations. In the past, the application of standard survey methods by various humanitarian actors has been criticised [1]. Currently, different methods of conducting field surveys are the subject of debate among epidemiologists and their strengths and weakness have been described in the literature [2-6]. Beyond the technical arguments, decision makers may find it difficult to conceptualize what the estimates actually mean. For instance, what makes this particular situation an emergency? And how should the operational response - humanitarian, political, even military - be adapted accordingly [7,8]? This brings into question not only the quality of the survey methodology, but also the difficulties epidemiologists face in interpreting results and selecting the most important information to guide operations.As a case study, we reviewed publicly available field surveys of a current acute-on-chronic humanitarian crisis - North Kivu, Democratic Republic of Congo (DRC) - to examine the methodologies employed, the findings presented, the interpretation of the results and the recommendations made. The eastern DRC Province of North Kivu has been the scene of conflict that has erupted sporadically for over a decade (Figure 1). The most recent renewal of violence has forced some 250,000 people to flee their homes since August 2008 [9].We searched PubMed/Medline for articles published from January 1, 2006 to January 1, 2009, in English, French, German, and Spanish using the key words ["mortality" (major topic) OR "nutrition" (major topic)] AND ["Congo" (text word)
Health care seeking behavior for diarrhea in children under 5 in rural Niger: results of a cross-sectional survey
Anne-Laure Page, Sarah Hustache, Francisco J Luquero, Ali Djibo, Mahamane Manzo, Rebecca F Grais
BMC Public Health , 2011, DOI: 10.1186/1471-2458-11-389
Abstract: A cluster survey was done on 35 clusters of 21 children under 5 years of age in each of four districts of the Maradi Region, Niger. Caretakers were asked about diarrhea of the child during the recall period and their health seeking behavior in case of diarrhea. A weighted cluster analysis was conducted to determine the prevalence of diarrhea, as well as the proportion of consultations and types of health structures consulted.In total, the period prevalence of diarrhea and severe diarrhea between April 24th and May 21st 2009 were 36.8% (95% CI: 33.7 - 40.0) and 3.4% (95% CI: 2.2-4.6), respectively. Of those reporting an episode of diarrhea during the recall period, 70.4% (95% CI: 66.6-74.1) reported seeking care at a health structure. The main health structures visited were health centers, followed by health posts both for simple or severe diarrhea. Less than 10% of the children were brought to the hospital. The proportion of consultations was not associated with the level of education of the caretaker, but increased with the number of children in the household.The proportion of consultations for diarrhea cases in children under 5 years old was higher than those reported in previous surveys in Niger and elsewhere. Free health care for under 5 years old might have participated in this improvement. In this type of decentralized health systems, the WHO recommended hospital-based surveillance of severe diarrheal diseases would capture only a fraction of severe diarrhea. Lower levels of health structures should be considered to obtain informative data to ensure appropriate care and burden estimates.Although better sanitation, hygiene and access to care have successfully alleviated the burden of diarrheal diseases in developed countries [1,2], diarrhea remains the second leading cause of death in children under 5 years of age in the world, representing nearly one in five child deaths - about 1.5 million each year [3,4]. In sub-Saharan Africa, the etiology of diarrhea is se
Observational Bias during Nutrition Surveillance: Results of a Mixed Longitudinal and Cross-Sectional Data Collection System in Northern Nigeria
Emmanuel Grellety, Francisco J. Luquero, Christopher Mambula, Hassana H. Adamu, Greg Elder, Klaudia Porten
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0062767
Abstract: Background The Sahel is subject to seasonal hungry periods with increasing rates of malnutrition. In Northern Nigeria, there is no surveillance system and surveys are rare. The objectives were to analyse possible observational bias in a sentinel surveillance system using repeated mixed longitudinal/cross-sectional data and estimate the extent of seasonal variation. Methods Thirty clusters were randomly selected using probability proportional to size (PPS) sampling from Kazaure Local Government Area, Jigawa State. In each cluster, all the children aged 6–59 months within 20 randomly selected households had their mid-upper arm circumference measured and were tested for oedema. The surveys were repeated every 2 or 4 weeks. At each survey round, three of the clusters were randomly selected to be replaced by three new clusters chosen at random by PPS. The seasonal variation of acute malnutrition was assessed using cyclical regression. The effect of repeated visits to the same cluster was examined using general linear mixed effects models adjusted for the seasonal change. Results There was a significant seasonal fluctuation of Global Acute Malnutrition (GAM) with a peak in October. With each repeat survey of a cluster, the prevalence of GAM decreased by 1.6% (95% CI: 0.4 to 2.7; p = 0.012) relative to the prevalence observed during the previous visit after adjusting for seasonal change. Conclusions Northern Nigeria has a seasonal variation in the prevalence of acute malnutrition. Repeated surveys in the same cluster-village, even if different children are selected, lead to a progressive improvement of the nutritional status of that village. Sentinel site surveillance of nutritional status is prone to observational bias, with the sentinel site progressively deviating from that of the community it is presumed to represent.
The Impact of a One-Dose versus Two-Dose Oral Cholera Vaccine Regimen in Outbreak Settings: A Modeling Study
Andrew S. Azman?,Francisco J. Luquero,Iza Ciglenecki?,Rebecca F. Grais?,David A. Sack?,Justin Lessler
PLOS Medicine , 2015, DOI: 10.1371/journal.pmed.1001867
Abstract: Background In 2013, a stockpile of oral cholera vaccine (OCV) was created for use in outbreak response, but vaccine availability remains severely limited. Innovative strategies are needed to maximize the health impact and minimize the logistical barriers to using available vaccine. Here we ask under what conditions the use of one dose rather than the internationally licensed two-dose protocol may do both. Methods and Findings Using mathematical models we determined the minimum relative single-dose efficacy (MRSE) at which single-dose reactive campaigns are expected to be as or more effective than two-dose campaigns with the same amount of vaccine. Average one- and two-dose OCV effectiveness was estimated from published literature and compared to the MRSE. Results were applied to recent outbreaks in Haiti, Zimbabwe, and Guinea using stochastic simulations to illustrate the potential impact of one- and two-dose campaigns. At the start of an epidemic, a single dose must be 35%–56% as efficacious as two doses to avert the same number of cases with a fixed amount of vaccine (i.e., MRSE between 35% and 56%). This threshold decreases as vaccination is delayed. Short-term OCV effectiveness is estimated to be 77% (95% CI 57%–88%) for two doses and 44% (95% CI ?27% to 76%) for one dose. This results in a one-dose relative efficacy estimate of 57% (interquartile range 13%–88%), which is above conservative MRSE estimates. Using our best estimates of one- and two-dose efficacy, we projected that a single-dose reactive campaign could have prevented 70,584 (95% prediction interval [PI] 55,943–86,205) cases in Zimbabwe, 78,317 (95% PI 57,435–100,150) in Port-au-Prince, Haiti, and 2,826 (95% PI 2,490–3,170) cases in Conakry, Guinea: 1.1 to 1.2 times as many as a two-dose campaign. While extensive sensitivity analyses were performed, our projections of cases averted in past epidemics are based on severely limited single-dose efficacy data and may not fully capture uncertainty due to imperfect surveillance data and uncertainty about the transmission dynamics of cholera in each setting. Conclusions Reactive vaccination campaigns using a single dose of OCV may avert more cases and deaths than a standard two-dose campaign when vaccine supplies are limited, while at the same time reducing logistical complexity. These findings should motivate consideration of the trade-offs between one- and two-dose campaigns in resource-constrained settings, though further field efficacy data are needed and should be a priority in any one-dose campaign.
Measuring the Performance of Vaccination Programs Using Cross-Sectional Surveys: A Likelihood Framework and Retrospective Analysis
Justin Lessler ,C. Jessica E. Metcalf,Rebecca F. Grais,Francisco J. Luquero,Derek A. T. Cummings,Bryan T. Grenfell
PLOS Medicine , 2011, DOI: 10.1371/journal.pmed.1001110
Abstract: Background The performance of routine and supplemental immunization activities is usually measured by the administrative method: dividing the number of doses distributed by the size of the target population. This method leads to coverage estimates that are sometimes impossible (e.g., vaccination of 102% of the target population), and are generally inconsistent with the proportion found to be vaccinated in Demographic and Health Surveys (DHS). We describe a method that estimates the fraction of the population accessible to vaccination activities, as well as within-campaign inefficiencies, thus providing a consistent estimate of vaccination coverage. Methods and Findings We developed a likelihood framework for estimating the effective coverage of vaccination programs using cross-sectional surveys of vaccine coverage combined with administrative data. We applied our method to measles vaccination in three African countries: Ghana, Madagascar, and Sierra Leone, using data from each country's most recent DHS survey and administrative coverage data reported to the World Health Organization. We estimate that 93% (95% CI: 91, 94) of the population in Ghana was ever covered by any measles vaccination activity, 77% (95% CI: 78, 81) in Madagascar, and 69% (95% CI: 67, 70) in Sierra Leone. “Within-activity” inefficiencies were estimated to be low in Ghana, and higher in Sierra Leone and Madagascar. Our model successfully fits age-specific vaccination coverage levels seen in DHS data, which differ markedly from those predicted by na?ve extrapolation from country-reported and World Health Organization–adjusted vaccination coverage. Conclusions Combining administrative data with survey data substantially improves estimates of vaccination coverage. Estimates of the inefficiency of past vaccination activities and the proportion not covered by any activity allow us to more accurately predict the results of future activities and provide insight into the ways in which vaccination programs are failing to meet their goals. Please see later in the article for the Editors' Summary
Cholera Epidemic in Guinea-Bissau (2008): The Importance of “Place”
Francisco J. Luquero,Cunhate Na Banga,Daniel Remartínez,Pedro Pablo Palma,Emanuel Baron,Rebeca F. Grais
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0019005
Abstract: As resources are limited when responding to cholera outbreaks, knowledge about where to orient interventions is crucial. We describe the cholera epidemic affecting Guinea-Bissau in 2008 focusing on the geographical spread in order to guide prevention and control activities.
Feasibility of Mass Vaccination Campaign with Oral Cholera Vaccines in Response to an Outbreak in Guinea
Iza Ciglenecki ,Keita Sakoba,Francisco J. Luquero,Melat Heile,Christian Itama,Martin Mengel,Rebecca F. Grais,Francois Verhoustraeten,Dominique Legros
PLOS Medicine , 2013, DOI: 10.1371/journal.pmed.1001512
Abstract:
Urban Cholera Transmission Hotspots and Their Implications for Reactive Vaccination: Evidence from Bissau City, Guinea Bissau
Andrew S. Azman,Francisco J. Luquero,Amabelia Rodrigues,Pedro Pablo Palma,Rebecca F. Grais,Cunhate Na Banga,Bryan T. Grenfell,Justin Lessler
PLOS Neglected Tropical Diseases , 2012, DOI: 10.1371/journal.pntd.0001901
Abstract: Background Use of cholera vaccines in response to epidemics (reactive vaccination) may provide an effective supplement to traditional control measures. In Haiti, reactive vaccination was considered but, until recently, rejected in part due to limited global supply of vaccine. Using Bissau City, Guinea-Bissau as a case study, we explore neighborhood-level transmission dynamics to understand if, with limited vaccine and likely delays, reactive vaccination can significantly change the course of a cholera epidemic. Methods and Findings We fit a spatially explicit meta-population model of cholera transmission within Bissau City to data from 7,551 suspected cholera cases from a 2008 epidemic. We estimated the effect reactive vaccination campaigns would have had on the epidemic under different levels of vaccine coverage and campaign start dates. We compared highly focused and diffuse strategies for distributing vaccine throughout the city. We found wide variation in the efficiency of cholera transmission both within and between areas of the city. “Hotspots”, where transmission was most efficient, appear to drive the epidemic. In particular one area, Bandim, was a necessary driver of the 2008 epidemic in Bissau City. If vaccine supply were limited but could have been distributed within the first 80 days of the epidemic, targeting vaccination at Bandim would have averted the most cases both within this area and throughout the city. Regardless of the distribution strategy used, timely distribution of vaccine in response to an ongoing cholera epidemic can prevent cases and save lives. Conclusions Reactive vaccination can be a useful tool for controlling cholera epidemics, especially in urban areas like Bissau City. Particular neighborhoods may be responsible for driving a city's cholera epidemic; timely and targeted reactive vaccination at such neighborhoods may be the most effective way to prevent cholera cases both within that neighborhood and throughout the city.
First Outbreak Response Using an Oral Cholera Vaccine in Africa: Vaccine Coverage, Acceptability and Surveillance of Adverse Events, Guinea, 2012
Francisco J. Luquero ,Lise Grout,Iza Ciglenecki,Keita Sakoba,Bala Traore,Melat Heile,Alpha Amadou Dialo,Christian Itama,Micaela Serafini,Dominique Legros,Rebecca F. Grais
PLOS Neglected Tropical Diseases , 2013, DOI: 10.1371/journal.pntd.0002465
Abstract: Background Despite World Health Organization (WHO) prequalification of two safe and effective oral cholera vaccines (OCV), concerns about the acceptability, potential diversion of resources, cost and feasibility of implementing timely campaigns has discouraged their use. In 2012, the Ministry of Health of Guinea, with the support of Médecins Sans Frontières organized the first mass vaccination campaign using a two-dose OCV (Shanchol) as an additional control measure to respond to the on-going nationwide epidemic. Overall, 316,250 vaccines were delivered. Here, we present the results of vaccination coverage, acceptability and surveillance of adverse events. Methodology/Principal Findings We performed a cross-sectional cluster survey and implemented adverse event surveillance. The study population included individuals older than 12 months, eligible for vaccination, and residing in the areas targeted for vaccination (Forécariah and Boffa, Guinea). Data sources were household interviews with verification by vaccination card and notifications of adverse events from surveillance at vaccination posts and health centres. In total 5,248 people were included in the survey, 3,993 in Boffa and 1,255 in Forécariah. Overall, 89.4% [95%CI:86.4–91.8%] and 87.7% [95%CI:84.2–90.6%] were vaccinated during the first round and 79.8% [95%CI:75.6–83.4%] and 82.9% [95%CI:76.6–87.7%] during the second round in Boffa and Forécariah respectively. The two dose vaccine coverage (including card and oral reporting) was 75.8% [95%CI: 71.2–75.9%] in Boffa and 75.9% [95%CI: 69.8–80.9%] in Forécariah respectively. Vaccination coverage was higher in children. The main reason for non-vaccination was absence. No severe adverse events were notified. Conclusions/Significance The well-accepted mass vaccination campaign reached high coverage in a remote area with a mobile population. Although OCV should not be foreseen as the long-term solution for global cholera control, they should be integrated as an additional tool into the response.
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