Combination chemotherapy of schistosomiasis in laboratory studies and clinical trials.
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Animals↗
Biomedical subjects
Burton H Singer
Publications and source records attributed to Burton H Singer.
Random spatial distribution of Schistosoma mansoni and hookworm infections among school children within a single village.
Schistosomes and soil-transmitted helminths currently infect a third of the world's human population. An important feature of these parasitic infections is their focal distribution, which has significant implications for control. Only a few studies have been carried out at the microepidemiological scale, comparing infection levels among individuals or households within a single village. In this study, data are presented from a cross-sectional survey, examining all children attending a primary school in rural Côte d'Ivoire over several consecutive days for Schistosoma mansoni, soil-transmitted helminths, and intestinal protozoa. All houses in the main village were mapped, and school children were linked to these households for small-area spatial analyses. Comparison between the 260 school children who live within the main village and the 89 children who reside in nearby settlements revealed significant differences in the overall prevalence and intensity of infections with S. mansoni and hookworm, confirming the focal nature of these 2 parasites. On the other hand, S. mansoni and hookworm infections exhibited random spatial patterns within the main village. The validity of these results is discussed in the context of this epidemiological setting, drawing attention to the issue of scale. Our findings have direct implications for intervention because they call for a uniform, community-wide approach to control schistosomiasis and soil-transmitted helminthiasis. Implementation can be relatively straightforward, and the proposed control approach might be cost-effective and prove sustainable.
Adolescent↗
Integrated programme is key to malaria control.
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Africa↗
Association between Schistosoma mansoni and hookworm infections among schoolchildren in Côte d'Ivoire.
Infections with Schistosoma mansoni and hookworms are widespread in sub-Saharan Africa and the burden of disease associated with both parasites is enormous. Although there is a large overlap in their geographic distribution, little is known about the association between S. mansoni and hookworm infections and the underlying mechanisms. We explored this association among 325 schoolchildren from Côte d'Ivoire, by screening multiple stool specimens over consecutive days. We found a highly significant positive association between S. mansoni and hookworm infections with an adjusted odds ratio of 2.25 (95% confidence interval: 1.31-3.85; P=0.003). Increasing infection intensity of S. mansoni was significantly correlated with an increased likelihood of concomitant hookworm infections (chi(2)=20.72; P<0.001). Egg counts in stool specimens derived from a single day did not consistently reveal the positive association between the two parasites, which underlines the importance of repeated stool examinations. Several self-reported water contact patterns were significantly associated either with S. mansoni, hookworm or concomitant infections. Our findings are of considerable importance for tailoring effective health education messages that are readily adapted to the local epidemiological setting. Complemented with other control interventions, these measures might significantly reduce the burden caused by S. mansoni and hookworm infections.
Adolescent↗
Allostatic load as a predictor of functional decline. MacArthur studies of successful aging.
Allostatic load has been proposed as a cumulative measure of dysregulation across multiple physiological systems, and has been postulated to impact health risks. In the allostatic load model, increased risk is hypothesized to result not only from large and clinically significant dysregulation in individual systems, but also from more modest dysregulation, if present in multiple systems. Our objective was to construct an allostatic load score by optimally combining several physiologic measurements, and to examine its association with future functional decline. We analyzed data from a 7-year longitudinal study of a community-based cohort, whose age at baseline was between 70 and 79 years. Canonical correlation analysis was used to study the association of 10 biological measurements representing allostatic load with declines in scores on five tests each of physical and cognitive function over two follow-up periods: 1998-1991 and 1991-1995. We used bootstrapping to evaluate the stability of the canonical correlation and canonical weights. The canonical correlation between allostatic load and the 20 decline scores was 0.43 (P =.03) and the [25th, 75th] percentile interval of its distribution over 200 bootstrapped subsamples of the cohort was [0.48, 0.53]. These findings were not substantially affected by adjusting for covariates and cardiovascular disease. We conclude that a summary measure of physiologic dysregulation, such as allostatic load, is an independent predictor of functional decline in elderly men and women.
Adaptation, Physiological↗
The economic payoffs of integrated malaria control in the Zambian copperbelt between 1930 and 1950.
It has long been suggested that malaria is delaying the economic development of countries that are most severely affected by the disease. Several studies have documented the economic consequences of malaria at the household level, primarily in communities engaged in subsistence farming. A missing element is the appraisal of the economic impact of malaria on the industrial and service sectors that will probably become the backbone of many developing economies. We estimate the economic effects of integrated malaria control implemented during the colonial period and sustained for 20 years in four copper mining communities of the former Northern Rhodesia (now Zambia). Integrated malaria control was characterized by strong emphasis on environmental management, while part of the mining communities also benefited from rapid diagnosis and treatment and the use of bednets. The programmes were highly successful as an estimated 14,122 deaths, 517,284 malaria attacks and 942,347 work shift losses were averted. Overall, 127,226 disability adjusted life years (DALYs) were averted per 3-year incremental period. The cumulative costs of malaria control interventions were 11,169,472 US dollars (in 1995 US dollars). Because the control programmes were so effective, the mining companies attracted a large reservoir of migrant labourers and sustained healthy work forces. The programmes averted an estimated 796,622 US dollars in direct treatment costs and 5,678,745 US dollars in indirect costs as a result of reduced work absenteeism. Within a few years of programme initiation, Northern Rhodesia became the leading copper producer in Africa, and mining generated the dominant share of national income. Copper production and revenues, which increased dramatically during malaria control interventions, amounted to the equivalent of 7.1 billion US dollars (in 1995 US dollars). Integrated malaria control in copper mining communities was a sound investment. It had payoff for public and occupational health, generally, and without it copper extraction and social and economic development would have been impossible.
Absenteeism↗
A gender gap in the next generation of physician-scientists: medical student interest and participation in research.
BACKGROUND: For 2 decades, the number of physician-scientists has not kept pace with the overall growth of the medical research community. Concomitantly, the number of women entering medical schools has increased markedly. We have explored the effect of the changing gender composition of medical schools on the present and future pipeline of young physician-scientists. METHODS: We analyzed data obtained from the Association of American Medical Colleges, the National Institutes of Health, and the Howard Hughes Medical Institute pertaining to the expressed research intentions or research participation of male and female medical students in the United States. RESULTS: A statistically significant decline in the percentage of matriculating and graduating medical students--both men and women-who expressed strong research career intentions occurred during the decade between 1987 and 1997. Moreover, matriculating and graduating women were significantly less likely than men to indicate strong research career intentions. Each of these trends has been observed for medical schools overall and for research-intensive ones. Cohort data obtained by tracking individuals from matriculation to graduation revealed that women who expressed strong research career intentions upon matriculation were more likely than men to decrease their research career intentions during medical school. Medical student participation in research supported the gender gap identified by assessing research intentions. Female medical student participation in the Medical Scientist Training Program and the Howard Hughes Medical Institute/National Institutes of Health-sponsored Cloisters Program has increased but lags far behind the growth in the female population in medical schools. CONCLUSION: Three worrisome trends in the research career intentions and participation of the nation's medical students (a decade-long decline for both men and women, a large and persistent gender gap, and a negative effect of the medical school experience for women) presage a further decline in the physician-scientist pipeline unless they are reversed promptly and decisively.
Biomedical Research↗
Polyparasitism with Schistosoma mansoni, geohelminths, and intestinal protozoa in rural Côte d'Ivoire.
Single species infections with schistosomes, geohelminths, and intestinal protozoans are common over large parts of sub-Saharan Africa, and it is expected that polyparasitism affects a considerable proportion of the population, hence posing a great toll on public health. However, few investigations have been carried out to quantify the extent of polyparasitism. Here, a detailed assessment is reported for the epidemiology of Schistosoma mansoni, geohelminths, and intestinal protozoan infections, with particular emphasis on polyparasitism among 260 community members in rural Cĵte d'Ivoire. Schistosoma mansoni, Entamoeba coli, and hookworm were the predominant species with prevalences of 71.5, 64.6, and 51.9%, respectively. Only 8 individuals displayed no infection, whereas two-thirds of the population harbored 3 or more parasites concurrently. There were a series of significant pairwise parasite co-occurrences, e.g., between S. mansoni and hookworms and between S. mansoni and E. coli. It is concluded that polyparasitism in the population studied here was very common, which is probably the case also in other areas of rural Cĵte d'Ivoire and elsewhere in sub-Saharan Africa. These findings call for integrated approaches to effectively control multiple parasitic and protozoan infections.
Adolescent↗
The potential of intermittent irrigation for increasing rice yields, lowering water consumption, reducing methane emissions, and controlling malaria in African rice fields.
Rice production in sub-Saharan Africa has more than doubled in the last 3 decades and the potential to further develop rice-harvested areas is considerable. Several studies have demonstrated that the transformation of arable land into rice irrigation might create suitable habitats for large populations of disease vectors. Prominent among those are anopheline mosquitoes responsible for transmission of malaria. The method of irrigation on an intermittent basis during the rice-cropping calendar has gained renewed interest as a potentially effective malaria control strategy since the early 1980s. We review the experiences of the past 80 years with intermittent irrigation in the cultivation of rice. This method has been shown to reduce significantly the density of malaria vectors by curtailing their larval development. Furthermore, reduced methane emissions and water savings with at least equal yields were achieved in intermittently irrigated rice fields. We explore and discuss under what conditions intermittent irrigation might be beneficial in new rice-growing areas and identify steps that have to be taken to expand such programs in the future.
Africa South of the Sahara↗
Social relationships, gender, and allostatic load across two age cohorts.
OBJECTIVE: This article addresses the question of biological pathways through which social integration and support may affect morbidity and mortality risks. A new concept of cumulative biological risk, allostatic load, is used to test the hypothesis that social experiences affect a range of biological systems. Data from two community-based cohorts are examined to evaluate the consistency of findings across two different age groups. METHODS: One cohort included older adults aged 70 to 79 years (N = 765); the other cohort included persons aged 58 to 59 years (N = 106). Allostatic load was assessed using identical protocols in the two cohorts. Measures of social experience were similar but not identical, reflecting levels of social integration and support for the older cohort vs. childhood and adult experiences of loving/caring relationships with parents and spouse for the younger cohort. Gender-specific analyses were examined to evaluate possible gender differences in patterns of association. RESULTS: In the younger cohort, positive cumulative relationship experiences were associated with lower allostatic load for men and women. In the older cohort, men who were more socially integrated and those reporting more frequent emotional support from others had lower allostatic load scores; similar but nonsignificant associations were seen for women. CONCLUSIONS: Evidence from two cohorts provides support for the hypothesis that positive social experiences are associated with lower allostatic load. These findings are consistent with the hypothesis that social experiences affect a range of biological systems, resulting in cumulative differences in risks that in turn may affect a range of health outcomes.
Aged↗