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Showing papers by "World Health Organization published in 2000"


Journal ArticleDOI
TL;DR: There is need for increased support for schistosomiasis control in the most severely affected countries, which are among the least developed whose health systems face difficulties to provide basic care at the primary health level.

1,292 citations


Journal ArticleDOI
TL;DR: Public health officials must gain a better understanding of the magnitude and characteristics of the problem, contribute to the development and evaluation of injury prevention programs, and develop the best possible prehospital and hospital care and rehabilitation for injured persons.
Abstract: The traditional view of injuries as "accidents", or random events, has resulted in the historical neglect of this area of public health. However, the most recent estimates show that injuries are among the leading causes of death and disability in the world. They affect all populations, regardless of age, sex, income, or geographic region. In 1998, about 5.8 million people (97.9 per 100,000 population) died of injuries worldwide, and injuries caused 16% of the global burden of disease. Road traffic injuries are the 10th leading cause of death and the 9th leading cause of the burden of disease; self-inflicted injuries, falls, and interpersonal violence follow closely. Injuries affect mostly young people, often causing long-term disability. Decreasing the burden of injuries is among the main challenges for public health in the next century--injuries are preventable, and many effective strategies are available. Public health officials must gain a better understanding of the magnitude and characteristics of the problem, contribute to the development and evaluation of injury prevention programs, and develop the best possible prehospital and hospital care and rehabilitation for injured persons.

1,232 citations


Journal ArticleDOI
01 Mar 2000-JAMA
TL;DR: Current knowledge of mother-to-child HIV transmission in developing countries is reviewed, key findings from the trials are summarized, future research requirements are outlined, and public health challenges of implementing perinatal HIV prevention interventions in resource-poor settings are described.
Abstract: Each year, an estimated 590,000 infants acquire human immunodeficiency virus type 1 (HIV) infection from their mothers, mostly in developing countries that are unable to implement interventions now standard in the industrialized world. In resource-poor settings, the HIV pandemic has eroded hard-won gains in infant and child survival. Recent clinical trial results from international settings suggest that short-course antiretroviral regimens could significantly reduce perinatal HIV transmission worldwide if research findings could be translated into practice. This article reviews current knowledge of mother-to-child HIV transmission in developing countries, summarizes key findings from the trials, outlines future research requirements, and describes public health challenges of implementing perinatal HIV prevention interventions in resource-poor settings. Public health efforts must also emphasize primary prevention strategies to reduce incident HIV infections among adolescents and women of childbearing age. Successful implementation of available perinatal HIV interventions could substantially improve global child survival.

1,155 citations


Journal ArticleDOI
TL;DR: By investigating four key functions of the health system and how they combine, it is possible not only to understand the proximate determinants of health system performance, but also to contemplate major policy challenges.
Abstract: Health systems vary widely in performance, and countries with similar levels of income, education and health expenditure differ in their ability to attain key health goals. This paper proposes a framework to advance the understanding of health system performance. A first step is to define the boundaries of the health system, based on the concept of health action. Health action is defined as any set of activities whose primary intent is to improve or maintain health. Within these boundaries, the concept of performance is centred around three fundamental goals: improving health, enhancing responsiveness to the expectations of the population, and assuring fairness of financial contribution. Improving health means both increasing the average health status and reducing health inequalities. Responsiveness includes two major components: (a) respect for persons (including dignity, confidentiality and autonomy of individuals and families to decide about their own health); and (b) client orientation (including prompt attention, access to social support networks during care, quality of basic amenities and choice of provider). Fairness of financial contribution means that every household pays a fair share of the total health bill for a country (which may mean that very poor households pay nothing at all). This implies that everyone is protected from financial risks due to health care. The measurement of performance relates goal attainment to the resources available. Variation in performance is a function of the way in which the health system organizes four key functions: stewardship (a broader concept than regulation); financing (including revenue collection, fund pooling and purchasing); service provision (for personal and non-personal health services); and resource generation (including personnel, facilities and knowledge). By investigating these four functions and how they combine, it is possible not only to understand the proximate determinants of health system performance, but also to contemplate major policy challenges.

870 citations


Journal ArticleDOI
TL;DR: This paper reviews the valid species of Cryptosporidium, their hosts and morphometrics; the reported hosts for the human pathogen, C. parvum; the mechanisms of transmission; the drinking water, recreational water, and food-borne outbreaks resulting from infection with C.parvum%; and the microscopic, immunological, and molecular methods used to detect and identify species and genotypes.

852 citations


Journal ArticleDOI
TL;DR: In this paper, the authors reviewed the nature and importance of environmental exposure to lead in developing and developed countries, outlining past actions, and indicating requirements for future policy responses and interventions.
Abstract: Lead is the most abundant of the heavy metals in the Earth’s crust. It has been used since prehistoric times, and has become widely distributed and mobilized in the environment. Exposure to and uptake of this non-essential element have consequently increased. Both occupational and environmental exposures to lead remain a serious problem in many developing and industrializing countries, as well as in some developed countries. In most developed countries, however, introduction of lead into the human environment has decreased in recent years, largely due to public health campaigns and a decline in its commercial usage, particularly in petrol. Acute lead poisoning has become rare in such countries, but chronic exposure to low levels of the metal is still a public health issue, especially among some minorities and socioeconomically disadvantaged groups. In developing countries, awareness of the public health impact of exposure to lead is growing but relatively few of these countries have introduced policies and regulations for significantly combating the problem. This article reviews the nature and importance of environmental exposure to lead in developing and developed countries, outlining past actions, and indicating requirements for future policy responses and interventions.

842 citations


Journal ArticleDOI
TL;DR: The most commonly studied genotoxicity endpoints have been selected for inclusion in this document and they are structural and numerical chromosomal aberrations assessed using cytogenetic methods (classical chromosomal aberration analysis (CA), fluorescence in situ hybridisation (FISH), micronuclei (MN), DNA damage (adducts, strand breaks, crosslinking, alkali-labile sites) assessed using bio-chemical/electrophoretic assays or sister chromatid exchanges (SCE); protein adducts; and hypoxanthine-
Abstract: The purpose of these guidelines is to provide concise guidance on the planning, performing and interpretation of studies to monitor groups or individuals exposed to genotoxic agents. Most human carcinogens are genotoxic but not all genotoxic agents have been shown to be carcinogenic in humans. Although the main interest in these studies is due to the association of genotoxicity with carcinogenicity, there is also an inherent interest in monitoring human genotoxicity independently of cancer as an endpoint. The most often studied genotoxicity endpoints have been selected for inclusion in this document and they are structural and numerical chromosomal aberrations assessed using cytogenetic methods (classical chromosomal aberration analysis (CA), fluorescence in situ hybridisation (FISH), micronuclei (MN)); DNA damage (adducts, strand breaks, crosslinking, alkali-labile sites) assessed using bio-chemical/electrophoretic assays or sister chromatid exchanges (SCE); protein adducts; and hypoxanthine-guanine phosphoribosyltransferase (HPRT) mutations. The document does not consider germ cells or gene mutation assays other than HPRT or markers of oxidative stress, which have been applied on a more limited scale.

756 citations


Journal ArticleDOI
TL;DR: Estimates show that attention should be paid to monitoring levels and trends of overweight in children, however, not at the expense of decreasing international commitments to alleviating undernutrition.

680 citations


Journal ArticleDOI
TL;DR: Rationales and evidence are presented to justify ensuring the widest possible coverage for preschool-age children and girls and women of childbearing age in intestinal parasite control programmes, in order to prevent morbidity and mortality in general and specifically to help decrease the vicious intergenerational cycle of growth failure.
Abstract: The Global Burden of Disease caused by the 3 major intestinal nematodes is an estimated 22.1 million disability-adjusted life-years (DALYs) lost for hookworm, 10.5 million for Ascaris lumbricoides, 6.4 million for Trichuris trichiura, and 39.0 million for the three infections combined (as compared with malaria at 35.7 million) (World Bank, 1993; Chan et al. 1994); these figures illustrate why some scarce health care resources must be used for their control. Strongyloides stercoralis is the fourth most important intestinal worm infection; its nutritional implications are discussed, and the fact that its geographic distribution needs further study is emphasized. Mechanisms underlying the malnutrition induced by intestinal helminths are described. Anorexia, which can decrease intake of all nutrients in tropical populations on marginal diets, is likely to be the most important in terms of magnitude and the probable major mechanism by which intestinal nematodes inhibit growth and development. We present a revised and expanded conceptual framework for how parasites cause/aggravate malnutrition and retard development in endemic areas. Specific negative effects that a wide variety of parasites may have on gastrointestinal physiology are presented. The synergism between Trichuris and Campylobacter, intestinal inflammation and growth failure, and new studies showing that hookworm inhibits growth and promotes anaemia in preschool (as well as school-age) children are presented. We conclude by presenting rationales and evidence to justify ensuring the widest possible coverage for preschool-age children and girls and women of childbearing age in intestinal parasite control programmes, in order to prevent morbidity and mortality in general and specifically to help decrease the vicious intergenerational cycle of growth failure (of low-birth-weight/intrauterine growth retardation and stunting) that entraps infants, children and girls and women of reproductive age in developing areas.

658 citations


Journal ArticleDOI
TL;DR: The data presented provide a baseline for assessing progress and help identify countries and regions in need of populationwide interventions and approaches to lower child malnutrition should be based on successful nutrition programmes and policies.
Abstract: Nutritional status is the best global indicator of well-being in children. Although many surveys of children have been conducted since the 1970s, lack of comparability between them has made it difficult to monitor trends in child malnutrition. Cross-sectional data from 241 nationally representative surveys were analysed in a standard way to produce comparable results of low height-for-age (stunting). Multilevel modelling was applied to estimate regional and global trends from 1980 to 2005. The prevalence of stunting has fallen in developing countries from 47% in 1980 to 33% in 2000 (i.e. by 40 million), although progress has been uneven according to regions. Stunting has increased in Eastern Africa, but decreased in South-eastern Asia, South-central Asia and South America; Northern Africa and the Caribbean show modest improvement; and Western Africa and Central America present very little progress. Despite an overall decrease of stunting in developing countries, child malnutrition still remains a major public health problem in these countries. In some countries rates of stunting are rising, while in many others they remain disturbingly high. The data we have presented provide a baseline for assessing progress and help identify countries and regions in need of populationwide interventions. Approaches to lower child malnutrition should be based on successful nutrition programmes and policies.

562 citations


Journal ArticleDOI
17 May 2000-JAMA
TL;DR: In this paper, the authors investigated the impact of multidrug-resistant tuberculosis (TB) on the outcome of standard short-course chemotherapy under countrywide TB control program conditions in the World Health Organization's
Abstract: ContextNo large-scale study has investigated the impact of multidrug-resistant tuberculosis (TB) on the outcome of standard short-course chemotherapy under routine countrywide TB control program conditions in the World Health Organization's (WHO) directly observed treatment short-course strategy for TB control.ObjectiveTo assess the results of treatment with first-line drugs for patients enrolled in the WHO and the International Union Against Tuberculosis and Lung Disease's global project on drug-resistance surveillance.Design and SettingRetrospective cohort study of patients with TB in the Dominican Republic, Hong Kong Special Administrative Region (People's Republic of China), Italy, Ivanovo Oblast (Russian Federation), the Republic of Korea, and Peru.PatientsNew and retreatment TB cases who received short-course chemotherapy with isoniazid, rifampicin, pyrazinamide, and either ethambutol or streptomycin between 1994 and 1996.Main Outcome MeasureTreatment response according to WHO treatment outcome categories (cured; died; completed, defaulted, or failed treatment; or transferred).ResultsOf the 6402 culture-positive TB cases evaluated, 5526 (86%) were new cases and 876 (14%) were retreatment cases. A total of 1148 (20.8%) new cases and 390 (44.5%) retreatment cases were drug resistant, including 184 and 169 cases of multidrug-resistant TB, respectively. Of the new cases 4585 (83%) were treated successfully, 138 (2%) died, and 151 (3%) experienced short-course chemotherapy failure. Overall, treatment failure (relative risk [RR], 15.4; 95% confidence interval [CI], 10.6-22.4; P<.001) and mortality (RR, 3.73; 95% CI, 2.13-6.53; P<.001) were higher among new multidrug-resistant TB cases than among new susceptible cases. Even in settings using 100% direct observation, cases with multidrug resistance had a significantly higher failure rate than those who were susceptible (9/94 [10%] vs 8/1410 [0.7%]; RR, 16.9; 95% CI, 6.6-42.7; P<.001). Treatment failure was also higher among patients with any rifampicin resistance (n=115) other than multidrug resistance (RR, 5.48; 95% CI, 3.04-9.87; P<.001), any isoniazid resistance (n=457) other than multidrug resistance (RR, 3.06; 95% CI, 1.85-5.05; P<.001), and among patients with TB resistant to rifampicin only (n=76) (RR, 5.47; 95% CI, 2.68-11.2; P<.001). Of the retreatment cases, 497 (57%) were treated successfully, 51 (6%) died, and 124 (14%) failed short-course chemotherapy treatment. Failure rates among retreatment cases were higher in those with multidrug-resistant TB, with any isoniazid resistance other than multidrug resistance, and in cases with TB resistant to isoniazid only.ConclusionsThese data suggest that standard short-course chemotherapy, based on first-line drugs, is an inadequate treatment for some patients with drug-resistant TB. Although the directly observed treatment short-course strategy is the basis of good TB control, the strategy should be modified in some settings to identify drug-resistant cases sooner, and to make use of second-line drugs in appropriate treatment regimens.

Journal ArticleDOI
01 May 2000-Stroke
TL;DR: Using a uniform methodology, the WHO MONICA Project has shown very large variations in attack rates of SAH across 11 populations in Europe and China, adding to the wide gap in the burden of stroke between East and West Europe.
Abstract: Background and Purpose —By official, mostly unvalidated statistics, mortality from subarachnoid hemorrhage (SAH) show large variations between countries. Using uniform criteria for case ascertainment and diagnosis, a multinational comparison of attack rates and case fatality rates of SAH has been performed within the framework of the WHO MONICA Project. Methods —In 25- to 64-year-old men and women, a total of 3368 SAH events were recorded during 35.9 million person-years of observation in 11 populations in Europe and China. Strict MONICA criteria were used for case ascertainment and diagnosis of stroke subtype. Case fatality was based on follow-up at 28 days after onset. Results —Age-adjusted average annual SAH attack rates varied 10-fold among the 11 populations studied, from 2.0 (95% CI 1.6 to 2.4) per 100 000 population per year in China-Beijing to 22.5 (95% CI 20.9 to 24.1) per 100 000 population per year in Finland. No consistent pattern was observed in the sex ratio of attack rates in the different populations. The overall 28-day case fatality rate was 42%, with 2-fold differences in age-adjusted rates between populations but little difference between men and women. Case fatality rates were consistently higher in Eastern than in Western Europe. Conclusions —Using a uniform methodology, the WHO MONICA Project has shown very large variations in attack rates of SAH across 11 populations in Europe and China. The generally accepted view that women have a higher risk of SAH than men does not apply to all populations. Marked differences in outcome of SAH add to the wide gap in the burden of stroke between East and West Europe.

Journal ArticleDOI
TL;DR: The prevalence of reduced vision is very low in school-age children in Nepal, most of it because of correctable refractive error, and the prevalence of myopia is higher for more recent birth cohorts.

Journal ArticleDOI
TL;DR: In this paper, the authors used location information to assist the targeting of interventions against malaria at the focal and household levels, leading to improved effectiveness and cost-effectiveness of control.
Abstract: Malaria transmission is strongly associated with location. This association has two main features. First, the disease is focused around specific mosquito breeding sites and can normally be transmitted only within certain distances from them: in Africa these are typically between a few hundred metres and a kilometre and rarely exceed 2-3 kilometres. Second, there is a marked clustering of persons with malaria parasites and clinical symptoms at particular sites, usually households. In localities of low endemicity the level of malaria risk or case incidence may vary widely between households because the specific characteristics of houses and their locations affect contact between humans and vectors. Where endemicity is high, differences in human/vector contact rates between different households may have less effect on malaria case incidences. This is because superinfection and exposure-acquired immunity blur the proportional relationship between inoculation rates and case incidences. Accurate information on the distribution of malaria on the ground permits interventions to be targeted towards the foci of transmission and the locations and households of high malaria risk within them. Such targeting greatly increases the effectiveness of control measures. On the other hand, the inadvertent exclusion of these locations causes potentially effective control measures to fail. The computerized mapping and management of location data in geographical information systems should greatly assist the targeting of interventions against malaria at the focal and household levels, leading to improved effectiveness and cost-effectiveness of control.

Journal ArticleDOI
18 Nov 2000-BMJ
TL;DR: Interpregnancy intervals less than 6 months and longer than 59 months are associated with an increased risk of adverse maternal outcomes.
Abstract: Objective: To study the impact of interpregnancy interval on maternal morbidity and mortality. Design: Retrospective cross sectional study with data from the Perinatal Information System database of the Latin American Centre for Perinatology and Human Development, Montevideo, Uruguay. Setting: Latin America and the Caribbean, 1985-97. Participants: 456 889 parous women delivering singleton infants. Main outcome measures: Crude and adjusted odds ratios of the effects of short and long interpregnancy intervals on maternal death, pre-eclampsia, eclampsia, gestational diabetes mellitus, third trimester bleeding, premature rupture of membranes, postpartum haemorrhage, puerperal endometritis, and anaemia. Results: Short ( 59 months) interpregnancy intervals were observed for 2.8% and 19.5% of women, respectively. After adjustment for major confounding factors, compared with those conceiving at 18 to 23 months after a previous birth, women with interpregnancy intervals of 5 months or less had higher risks for maternal death (odds ratio 2.54; 95% confidence interval 1.22 to 5.38), third trimester bleeding (1.73; 1.42 to 2.24), premature rupture of membranes (1.72; 1.53 to 1.93), puerperal endometritis (1.33; 1.22 to 1.45), and anaemia (1.30; 1.18 to 1.43). Compared with women with interpregnancy intervals of 18 to 23 months, women with interpregnancy intervals longer than 59 months had significantly increased risks of pre-eclampsia (1.83; 1.72 to 1.94) and eclampsia (1.80; 1.38 to 2.32). Conclusions: Interpregnancy intervals less than 6 months and longer than 59 months are associated with an increased risk of adverse maternal outcomes.

Journal ArticleDOI
TL;DR: The strategy for controlling diarrhoea through case management, with special reference to ORT, is reported on, and the relationship between its implementation and reduced mortality is examined, and there are important lessons for evaluators.
Abstract: In 1980, diarrhoea was the leading cause of child mortality, accounting for 4.6 million deaths annually. Efforts to control diarrhoea over the past decade have been based on multiple, potentially powerful interventions implemented more or less simultaneously. Oral rehydration therapy (ORT) was introduced in 1979 and rapidly became the cornerstone of programmes for the control of diarrhoeal diseases. We report on the strategy for controlling diarrhoea through case management, with special reference to ORT, and on the relationship between its implementation and reduced mortality. Population-based data on the coverage and quality of facility-based use of ORT are scarce, despite its potential importance in reducing mortality, especially for severe cases. ORT use rates during the 1980s are available for only a few countries. An improvement in the availability of data occurred in the mid-1990s. The study of time trends is hampered by the use of several different definitions of ORT. Nevertheless, the data show positive trends in diarrhoea management in most parts of the world. ORT is now given to the majority of children with diarrhoea. The annual number of deaths attributable to diarrhoea among children aged under 5 years fell from the estimated 4.6 million in 1980 to about 1.5 million today. Case studies in Brazil, Egypt, Mexico, and the Philippines confirm increases in the use of ORT which are concomitant with marked falls in mortality. In some countries, possible alternative explanations for the observed decline in mortality have been fairly confidently ruled out. Experience with ORT can provide useful guidance for child survival programmes. With adequate political will and financial support, cost-effective interventions other than that of immunization can be successfully delivered by national programmes. Furthermore, there are important lessons for evaluators. The population-based data needed to establish trends in health service delivery, outcomes and impact are not available in respect of diarrhoea, as is true for malaria, pneumonia and other major childhood conditions. Standard indicators and measurement methods should be established. Efforts to change existing global indicators should be firmly resisted. Support should be given for the continuing evaluation and documentation activities needed to guide future public health policies and programmes.

Journal ArticleDOI
TL;DR: The present paper examines, describes and documents country-specific trends in under-five mortality rates (i.e., mortality among children under five years of age) in the 1990s, and identifies countries and WHO regions where sustained improvement has occurred and those where setbacks are evident.
Abstract: The present paper examines, describes and documents country-specific trends in under-five mortality rates (i.e., mortality among children under five years of age) in the 1990s. Our analysis updates previous studies by UNICEF, the World Bank and the United Nations. It identifies countries and WHO regions where sustained improvement has occurred and those where setbacks are evident. A consistent series of estimates of under-five mortality rate is provided and an indication is given of historical trends during the period 1950-2000 for both developed and developing countries. It is estimated that 10.5 million children aged 0-4 years died in 1999, about 2.2 million or 17.5% fewer than a decade earlier. On average about 15% of newborn children in Africa are expected to die before reaching their fifth birthday. The corresponding figures for many other parts of the developing world are in the range 3-8% and that for Europe is under 2%. During the 1990s the decline in child mortality decelerated in all the WHO regions except the Western Pacific but there is no widespread evidence of rising child mortality rates. At the country level there are exceptions in southern Africa where the prevalence of HIV is extremely high and in Asia where a few countries are beset by economic difficulties. The slowdown in the rate of decline is of particular concern in Africa and South-East Asia because it is occurring at relatively high levels of mortality, and in countries experiencing severe economic dislocation. As the HIV/AIDS epidemic continues in Africa, particularly southern Africa, and in parts of Asia, further reductions in child mortality become increasingly unlikely until substantial progress in controlling the spread of HIV is achieved.

Journal ArticleDOI
TL;DR: Analysis of genetic distance between isolates was consistent with the introduction of multiple virus strains 75-140 years ago, and no clustering was detected within geographic regions, suggesting widespread dispersion at some time since then.
Abstract: Hepatitis C virus (HCV) infection is a major health problem in Egypt, where the seroprevalence is 10-20-fold higher than that in the United States. To characterize the HCV genotype distribution and concordance of genotype assessments on the basis of multiple genomic regions, specimens were obtained from blood donors in 15 geographically diverse governorates throughout Egypt. The 5' noncoding, core/E1, and NS5B regions were amplified by reverse transcription-polymerase chain reaction and analyzed by both restriction fragment length polymorphism (RFLP) and phylogenetic tree construction. For the 5' noncoding region, 122 (64%) of 190 specimens were amplified and analyzed by RFLP: 111 (91%) were genotype 4, 1 (1%) was genotype 1a, 1 (1%) was genotype 1b, and 9 (7%) could not be typed. Phylogenetic analyses of the core/E1 and NS5B regions confirmed the genotype 4 preponderance and revealed evidence of 3 new subtypes. Analysis of genetic distance between isolates was consistent with the introduction of multiple virus strains 75-140 years ago, and no clustering was detected within geographic regions, suggesting widespread dispersion at some time since then.

Journal ArticleDOI
TL;DR: The use of insecticide treated nets for personal protection against malaria vector Anopheles mosquitoes has become popular during the past decade, and with the precautions outlined in this paper, field use of pyrethroids poses little or no hazard to people treating the nets or to users of the treated nets.
Abstract: The use of insecticide treated nets (ITNs) for personal protection against malaria vector Anopheles mosquitoes (Diptera: Culicidae) has become popular during the past decade With the precautions outlined in this paper, field use of pyrethroids--at concentrations recommended for treatment of mosquito nets--poses little or no hazard to people treating the nets or to users of the treated nets With frequent exposure to low concentrations of pyrethroids, the risk of toxicity of any kind is remote Pyrethroids entering the systemic circulation are rapidly metabolized to much less toxic metabolites Toxicologically, pyrethroids have a useful characteristic--the production of skin paraesthesia--which gives an early indication of exposure This reversible symptom of exposure is due to transient stimulation of peripheral sensory nerves and not a toxic effect In the retail market, for home use, the provision of proper packaging and labelling, with clear instructions on safe and effective use of the product are most important Because many domestic users of pyrethroid 'home treatment kits' for ITNs may not be fully literate, it is essential that 'instructions for use' should be portrayed via pictograms with supporting text in appropriate local language(s)

Journal ArticleDOI
TL;DR: In this paper, recent reviews of the World Health Organization, other review papers, and more recent literature on the human health effects of current air pollution trends in urban areas are reviewed and summarized.
Abstract: In this paper, recent reviews of the World Health Organization, other review papers, and more recent literature on the human health effects of current air pollution trends in urban areas are reviewed and summarized as follows: Sulphur dioxide. Some studies, but not others, found associations between sulphur dioxide (SO2) exposure and daily mortality and morbidity. Single-pollutant correlations sometimes disappeared when other pollutants, especially suspended particulate matter (SPM), were included. Cross-sectional studies with asthmatics revealed significant, non-threshold relations between SO2 and decrements of the forced expiratory volume in 1 second (FEV1). Nitrogen dioxide. Weak associations between short-term nitrogen dioxide (NO2) exposure from gas cooking and respiratory symptoms and a decrement in lung function parameters were found in children, but not consistently in exposed women. With long-term exposure, children, but not adults, exhibit increased respiratory symptoms, decreased lung function, and increased incidences of chronic cough, bronchitis, and conjunctivitis. A causal relationship between NO2 exposure and adverse health effects has not yet been established. Carbon monoxide. Binding of CO in the lungs with hemoglobin in the blood forms carboxyhemoglobin (COHb), which impairs the transport of oxygen. The health effects of CO include hypoxia, neurological deficits and neurobehavioral changes, and increases in daily mortality and hospital admissions for cardiovascular diseases. The latter persists even at very low CO levels, indicating no threshold for the onset of these effects. Whether the relation between daily mortality and exposure to CO are causal or whether CO might act as a proxy for SPM is still an open question. Ambient CO may have even more serious health consequences than does COHb formation and at lower levels than that mediated through elevated COHb levels. Ozone. Short-term acute effects of O3 include pulmonary function decrements, increased airway responsiveness and airway inflammation, aggravation of pre-existing respiratory diseases like asthma, increases in daily hospital admissions and emergency department visits for respiratory causes, and excess mortality. Exposure-response relations are non-linear for the respective associations between O3 and FEV1, inflammatory changes, and changes in hospital admissions, whereas the relation between percent change in symptom exacerbation among adults and asthmatics is linear. Single-pollutant associations between O3 exposure and daily mortality and hospital admissions for respiratory diseases is statistically significant, even in multi-pollutant models. Suspended particulate matter. Associations between SPM concentrations and mortality and morbidity rates are significant. The acute health effects of SPM, even at short-term low levels of exposure, include increased daily mortality and hospital admission rates for exacerbation of respiratory disease, fluctuations in the prevalence of bronchodilator use, and cough and peak flow reductions, as well as long-term effects with respect to mortality and respiratory morbidity. Such effects depend on particle size and concentration and can fluctuate with daily fluctuations in PM10 or PM2.5 levels. The relation between PM10 or PM2.5 exposure and acute health effects is linear at concentrations below 100 micrograms/m3. Currently no threshold has been reported below which no effects occur. The influence of co-polluting gaseous pollutants could explain part of the observed variance in short-term health effects and reduce the contribution of SPM. Lead. The biological effects of lead can be related to blood lead levels, the best indicator of internal exposure. The potential effects of lead in adults and children include encephalopathic signs and symptoms, central nervous system symptoms, cognitive effects, increased blood pressure, and reduced measures of child intelligence. (ABSTRACT TRUNCATED)

Journal ArticleDOI
TL;DR: Mole characterization of morphologically identical isolates from humans and numerous other species of mammals has confirmed the heterogeneity of this parasite and provided a basis for a clearer understanding of the taxonomy and zoonotic potential of Giardia.

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TL;DR: The study design, sample size, and measurement methods ensure that the prevalence of age-specific and sex-specific refractive error can be estimated with reasonable accuracy in the target populations.

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TL;DR: A large cohort of Latin American and Caribbean women is studied for risk factors for pre‐eclampsia in a large group of women for the first time to study these factors and their impact on pregnancy and childbirth.

Journal ArticleDOI
TL;DR: A bias toward underreporting, as well as stronger agreement at the level of the depression syndrome and on ordinal measures of depressive symptoms, suggests that associations with risk factors are conservative.
Abstract: Background The field of psychiatric epidemiology continues to employ self-report instruments, but the low degree of agreement between diagnoses achieved using these instruments vs that achieved by psychiatrists in the clinical modality threatens the credibility of the results. Methods In the Baltimore Epidemiologic Catchment Area follow-up, 349 individuals who had a Diagnostic Interview Schedule (DIS) interview were blindly examined by psychiatrists using the Schedules for Clinical Assessment in Neuropsychiatry (SCAN). Comparisons were made at the level of diagnosis, syndrome, and DSM-IV symptom group. Indexes of agreement were computed and characteristics of discrepant cases were identified. Results Agreement on diagnosis of major depressive disorder was only fair (κ = 0.20), with the DIS missing many cases judged to meet criteria for diagnosis using the SCAN (29% sensitivity). A major source of discrepancy was respondents with false-negative diagnoses who repeatedly failed to report DIS symptoms attributed to life crises or medical conditions. Older age, male sex, and lower impairment were associated with underdetection by the DIS, using logistic regression analysis. In spite of the diagnostic discrepancy, there was substantial correlation in numbers of symptom groups in the 2 modalities ( r = 0.49). Agreement was highest (about 55% sensitivity and 90% specificity) when both the SCAN and DIS thresholds were set at the level of depression syndrome instead of diagnosis. Conclusions Weak agreement at the level of diagnosis continues to threaten the credibility of estimates of prevalence of specific disorders. A bias toward underreporting, as well as stronger agreement at the level of the depression syndrome and on ordinal measures of depressive symptoms, suggests that associations with risk factors are conservative.

Journal Article
TL;DR: It is proposed that health is an intrinsic component of well-being and thus it should be concerned with inequality in health, whether or not it is correlated withequality in other dimensions ofWell-being.
Abstract: This paper proposes an approach to conceptualizing and operationalizing the measurement of health inequality, defined as differences in health across individuals in the population. We propose that health is an intrinsic component of well-being and thus we should be concerned with inequality in health, whether or not it is correlated with inequality in other dimensions of well-being. In the measurement of health inequality, the complete range of fatal and non-fatal health outcomes should be incorporated. This notion is operationalized through the concept of healthy lifespan. Individual health expectancy is preferable, as a measurement, to individual healthy lifespan, since health expectancy excludes those differences in healthy lifespan that are simply due to chance. In other words, the quantity of interest for studying health inequality is the distribution of health expectancy across individuals in the population. The inequality of the distribution of health expectancy can be summarized by measures of individual/mean differences (differences between the individual and the mean of the population) or inter-individual differences. The exact form of the measure to summarize inequality depends on three normative choices. A firmer understanding of people's views on these normative choices will provide a basis for deliberating on a standard WHO measure of health inequality.

Journal ArticleDOI
TL;DR: The need for programs to consider reducing the prevalence of hookworm, malaria infection and vitamin A deficiency where indicated, in addition to providing iron supplements to effectively control anemia, is reinforced.
Abstract: Anemia and iron deficiency during pregnancy are prevalent in developing countries, but their causes are not always known. We assessed the prevalence and severity of anemia and iron deficiency and their association with helminths, malaria and vitamin A deficiency in a community-based sample of 336 pregnant women in the plains of Nepal. Hemoglobin, erythrocyte protoporphyrin (EP) and serum ferritin were assessed in venous blood samples. Overall, 72.6% of women were anemic (hemoglobin 70 micromol/mol heme or serum ferritin < 10 microg/L). Eighty-eight percent of cases of anemia were associated with iron deficiency. More than half of the women (54.2%) had a low serum retinol concentration (<1.05 micromol/L), 74.2% were infected with hookworms and 19.8% had Plasmodium vivax malaria parasitemia. Hemoglobin, EP and serum ferritin concentrations were significantly worse and the prevalence of anemia, elevated EP and low serum ferritin was increased with increasing intensity of hookworm infection. Hookworm infection intensity was the strongest predictor of iron status, especially of depleted iron stores. Low serum retinol was most strongly associated with mild anemia, whereas P. vivax malaria and hookworm infection intensity were stronger predictors of moderate to severe anemia. These findings reinforce the need for programs to consider reducing the prevalence of hookworm, malaria infection and vitamin A deficiency where indicated, in addition to providing iron supplements to effectively control anemia.

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TL;DR: The issues and challenges in the design and application of summary measures are reviewed, a framework for evaluating different alternatives is presented and a set of basic criteria and desirable properties that may lead to rejection of certain summary measures and the development of new ones are considered.
Abstract: In the past decade, interest has been rising in the development, calculation and use of summary measures of population health, which combine information on mortality and non-fatal health outcomes. This paper reviews the issues and challenges in the design and application of summary measures and presents a framework for evaluating different alternatives. Summary measures have a variety of uses, including comparisons of health in different populations and assessments of the relative contributions of different diseases, injuries and risk factors to the total disease burden in a population. Summary measures may be divided into two broad families: health expectancies and health gaps. Within each family, there are many different possible measures, but they share a number of inputs, including information on mortality, non-fatal health outcomes, and health state valuations. Other critical points include calculation methods and a range of conceptual and methodological issues regarding the definition, measurement and valuation of health states. This paper considers a set of basic criteria and desirable properties that may lead to rejection of certain summary measures and the development of new ones. Despite the extensive developmental agenda that remains, applications of summary measures cannot await the final resolution of all methodological issues, so they should focus on those measures that satisfy as many basic criteria and desirable properties as possible.

01 Jan 2000
TL;DR: In this article, the authors reviewed the valid species of Cryptosporidium, their hosts and morphometrics; the reported hosts for the human pathogen, C. parvum; the mechanisms of transmission; the drinking water, recreational water, and food-borne outbreaks resulting from infection with C.parvum, and the microscopic, immunological and molecular methods used to detect and identify species and genotypes.
Abstract: There are 10 valid species of Cryptosporidium and perhaps other cryptic species hidden under the umbrella of Cryptosporidium parvum. The oocyst stage is of primary importance for the dispersal, survival, and infectivity of the parasite and is of major importance for detection and identification. Because most oocysts measure 4-6 μm, appear nearly spherical, and have obscure internal structures, there are few or no morphometric features to differentiate species and in vitro cultivation does not provide differential data as for bacteria. Consequently, we rely on a combination of data from three tools: morphometrics, molecular techniques, and host specificity. Of 152 species of mammals reported to be infected with C. parvum or an indistinguishable organism, very few oocysts have ever been examined using more than one of these tools. This paper reviews the valid species of Cryptosporidium, their hosts and morphometrics; the reported hosts for the human pathogen, C. parvum; the mechanisms of transmission; the drinking water, recreational water, and food-borne outbreaks resulting from infection with C. parvum; and the microscopic, immunological, and molecular methods used to detect and identify species and genotypes.

Journal ArticleDOI
TL;DR: The results show that the GYTS surveillance system is enhancing the capacity of countries to design, implement, and evaluate tobacco prevention and control programmes.
Abstract: The Global Youth Tobacco Survey (GYTS) project was developed by the World Health Organization and the US Centers for Disease Control and Prevention to track tobacco use among youth in countries across the world, using a common methodology and core questionnaire. The GYTS is school based and employs a two-stage sample design to produce representative data on smoking among students aged 13-15 years. The first stage consists of a probabilistic selection of schools, and the second consists of a random selection of classes from the participating schools. All students in the selected classes are eligible for the survey. In 1999, the GYTS was conducted in 13 countries and is currently in progress in over 30 countries. This report describes data from 12 countries: Barbados, China, Costa Rica, Fiji, Jordan, Poland, the Russian Federation (Moscow), South Africa, Sri Lanka, Ukraine (Kiev), Venezuela, and Zimbabwe. The findings show that tobacco use in the surveyed age group ranged from a high of 33% to a low of 10%. While the majority of current smokers wanted to stop smoking, very few were able to attend a cessation programme. In most countries the majority of young people reported seeing advertisements for cigarettes in media outlets, but anti-tobacco advertising was rare. The majority of young people reported being taught in school about the dangers of smoking. Environmental tobacco smoke exposure was very high in all countries. These results show that the GYTS surveillance system is enhancing the capacity of countries to design, implement, and evaluate tobacco prevention and control programmes.

Journal ArticleDOI
TL;DR: A role for an early wave of PMN in the development of the Th2 response characteristic of mice susceptible to infection with L. major is suggested.
Abstract: The possible immunomodulatory role of polymorphonuclear leukocytes (PMN) in CD4+ T lymphocyte differentiation in mice was examined by studying the effect of transient depletion of PMN during the early phase after Leishmania major delivery. A single injection of the PMN-depleting NIMP-R14 mAb 6 h before infection with L. major prevented the early burst of IL-4 mRNA transcription otherwise occurring in the draining lymph node of susceptible BALB/c mice. Since this early burst of IL-4 mRNA transcripts had previously been shown to instruct Th2 differentiation in mice from this strain, we examined the effect of PMN depletion on Th subset differentiation at later time points after infection. The transient depletion of PMN in BALB/c mice was sufficient to inhibit Th2 cell development otherwise occurring after L. major infection. Decreased Th2 responses were paralleled with partial resolution of the footpad lesions induced by L. major. Furthermore, draining lymph node-derived CD4+ T cells from PMN-depleted mice remained responsive to IL-12 after L. major infection, unlike those of infected BALB/c mice receiving control Ab. PMN depletion had no effect when the NIMP-R14 mAb was injected 24 h postinfection. The protective effect of PMN depletion was shown to be IL-12 dependent, as concomitant neutralization of IL-12 reversed the protective effect of PMN depletion. These results suggest a role for an early wave of PMN in the development of the Th2 response characteristic of mice susceptible to infection with L. major.