World Health Organization

About: World Health Organization is a government organization based out in Islamabad, Pakistan. It is known for research contribution in the topics: Population & Public health. The organization has 13330 authors who have published 22232 publications receiving 1322023 citations. The organization is also known as: World Health Organisation & WHO.

Elaboración de valores de referencia de la OMS para el crecimiento de escolares y adolescentes

Abstract: Introduction The need to develop an appropriate single growth reference for the screening, surveillance and monitoring of school-aged children and adolescents has been stirred by two contemporary events: the increasing public health concern over childhood obesity (1) and the April 2006 release of the WHO Child Growth Standards for preschool children based on a prescriptive approach. (2) As countries proceed with the implementation of growth standards for children under 5 years of age, the gap across all centiles between these standards and existing growth references for older children has become a matter of great concern. It is now widely accepted that using descriptive samples of populations that reflect a secular trend towards overweight and obesity to construct growth references results inadvertently in an undesirable upward skewness leading to an underestimation of overweight and obesity, and an overestimation of undernutrition. (3) The reference previously recommended by WHO for children above 5 years of age, i.e. the National Center for Health Statistics (NCHS)/WHO international growth reference, (4) has several drawbacks. (5) In particular, the body mass index-for-age reference, developed in 1991, (6) only starts at 9 years of age, groups data annually and covers a limited percentile range. Many countries pointed to the need to have body mass index (BMI) curves that start at 5 years and permit unrestricted calculation of percentile and z-score curves on a continuous age scale from 5 to 19 years. The need to harmonize growth assessment tools conceptually and pragmatically prompted an expert group meeting in January 2006 to evaluate the feasibility of developing a single international growth reference for school-aged children and adolescents. (7,8) The experts agreed that appropriate growth references for these age groups should be developed for clinical and public health applications. They also agreed that a multicentre study, similar to the one that led to the development of the WHO Child Growth Standards for 0 to 5 years, would not be feasible for older children, as it would not be possible to control the dynamics of their environment. Therefore, as an alternative, the experts suggested that a growth reference be constructed for this age group using existing historical data and discussed the criteria for selecting the data sets. WHO subsequently initiated a process to identify existing data sets from various countries. This process resulted in an initial identification of 115 candidate data sets from 45 countries, which were narrowed down to 34 data sets from 22 countries that met the inclusion criteria developed by the expert group. However, after further review, even these most promising studies showed great heterogeneity in methods and data quality, sample size, age categories, socioeconomic status of participating children and various other factors critical to growth curve construction. Therefore, it was unlikely that a growth reference constructed from these heterogeneous data sets would agree with the WHO Child Growth Standards at 5 years of age for the different anthropometric indicators needed (i.e. height-for-age, weight-for-age and BMI-for-age). In consequence, WHO proceeded to reconstruct the 1977 NCHS/WHO growth reference from 5 to 19 years, using the original sample (a non-obese sample with expected heights), supplemented with data from the WHO Child Growth Standards (to facilitate a smooth transition at 5 years), and applying the state-of-the-art statistical methods (9,10) used to develop standards for preschool children, that is, the Box-Cox power exponential (BCPE) method with appropriate diagnostic tools for the selection of best models. The purposes of this paper are to report the methods used to reconstruct the 1977 NCHS/WHO growth reference, to compare the resulting new curves (the 2007 WHO reference) with the 1977 NCHS/WHO charts, and to describe the transition at 5 years of age from the WHO standards for under-fives to these new curves for school-aged children and adolescents. …

A molecular marker of artemisinin-resistant Plasmodium falciparum malaria

Abstract: Plasmodium falciparum resistance to artemisinin derivatives in southeast Asia threatens malaria control and elimination activities worldwide. To monitor the spread of artemisinin resistance, a molecular marker is urgently needed. Here, using whole-genome sequencing of an artemisinin-resistant parasite line from Africa and clinical parasite isolates from Cambodia, we associate mutations in the PF3D7_1343700 kelch propeller domain ('K13-propeller') with artemisinin resistance in vitro and in vivo. Mutant K13-propeller alleles cluster in Cambodian provinces where resistance is prevalent, and the increasing frequency of a dominant mutant K13-propeller allele correlates with the recent spread of resistance in western Cambodia. Strong correlations between the presence of a mutant allele, in vitro parasite survival rates and in vivo parasite clearance rates indicate that K13-propeller mutations are important determinants of artemisinin resistance. K13-propeller polymorphism constitutes a useful molecular marker for large-scale surveillance efforts to contain artemisinin resistance in the Greater Mekong Subregion and prevent its global spread.

Water sanitation and hygiene interventions to reduce diarrhoea in less developed countries: a systematic review and meta-analysis.

Abstract: Many studies have reported the results of interventions to reduce illness through improvements in drinking water, sanitation facilities, and hygiene practices in less developed countries. There has, however, been no formal systematic review and meta-analysis comparing the evidence of the relative effectiveness of these interventions. We developed a comprehensive search strategy designed to identify all peer-reviewed articles, in any language, that presented water, sanitation, or hygiene interventions. We examined only those articles with specific measurement of diarrhoea morbidity as a health outcome in non-outbreak conditions. We screened the titles and, where necessary, the abstracts of 2120 publications. 46 studies were judged to contain relevant evidence and were reviewed in detail. Data were extracted from these studies and pooled by meta-analysis to provide summary estimates of the effectiveness of each type of intervention. All of the interventions studied were found to reduce significantly the risks of diarrhoeal illness. Most of the interventions had a similar degree of impact on diarrhoeal illness, with the relative risk estimates from the overall meta-analyses ranging between 0·63 and 0·75. The results generally agree with those from previous reviews, but water quality interventions (point-of-use water treatment) were found to be more effective than previously thought, and multiple interventions (consisting of combined water, sanitation, and hygiene measures) were not more effective than interventions with a single focus. There is some evidence of publication bias in the findings from the hygiene and water treatment interventions.