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S Brooker

Publications and source records attributed to S Brooker.

At least 19 recordsLinked to original sources
PubMed2003

Estimating the number of helminthic infections in the Republic of Cameroon from data on infection prevalence in schoolchildren.

INTRODUCTION: The prevalence of infection with helminths is markedly dependent on age, yet estimates of the total number of infections are typically based on data only from school-aged children. Such estimates, although useful for advocacy, provide inadequate information for planning control programmes and for quantifying the burden of disease. Using readily available data on the prevalence of infection in schoolchildren, the relation between the prevalence of infection in school-aged children and prevalence in the wider community can be adequately described using species-specific models. This paper explores the reliability of this approach to predict the prevalence infection in the community and provides a model for estimating the total number of people infected in the Republic of Cameroon. METHODS: Using data on the prevalence of helminthic infection in school-aged children in Cameroon, the prevalence of infection in pre-school children and adults was estimated from species-specific linear and logistic regression models developed previously. The model predictions were then used to estimate the number of people infected in each district in each age group in Cameroon. RESULTS: For Cameroon, if only the prevalence of infection in schoolchildren is used, the number of people infected with each helminthic species will be overestimated by up to 32% when compared with the estimates provided by the species-specific models. The calculation of confidence intervals supports the statistical reliability of the model since a narrow range of parameter estimates is evident. Furthermore, this work suggests that estimation of national prevalence of infection and the number infected will be enhanced if data are stratified by age; this model represents a useful planning tool for obtaining more accurate estimates. Estimates based on data aggregated from three geographical levels (district, regional, and national) show that summarizing prevalence data at the national level will result in biases of up to 19%. Such biases reflect differences in the geographical distribution for the prevalence of each species. DISCUSSION: Developing more accurate estimates requires a better understanding of the differences in the spatial heterogeneity of each species and also better methods of incorporating this information when making estimates.

Adolescent↗
PubMed2001

Total synthesis of (+)-hatomarubigin B.

The first total synthesis of (+)-hatomarubigin 3 is described. The tetra-O-acetyl diborate promoted Diels-Alder reaction of 5-hydroxy-8-(2',3',4',6'-tetra-O-acetyl-beta-D-glucopyranosyloxy)-1,4-naphthoquinone 8 and (E, 1R*,5R*)-3-(2'-methoxyvinyl)cyclohex-2-enol (+/-)-7 gave a mixture of four cycloadducts from which (1S,3S,6S,6aR,12aR,12bS)-1,8-dihydroxy-6-dimethoxy-1-hydroxy-3-methyl-11-(2',3',4',6'-tetra-O-acetyl-beta-D-glucopyranosyloxy)-1,2,3,4,6,6a,12a,12b-octahydrobenz[a]anthracene-7,12-dione 12 was isolated in 51% yield. Selective methylation and acetylation of 12 gave (1S,3S,6S,6aR,12aR,12bS)-1-acetoxy-6,8-dimethoxy-3-methyl-11-(2,3,4,6-tetra-O-acetyl-alpha-D-glucopyranosyloxy)-1,2,3,4,6,6a,12a,12b-octahydrobenz[a]anthracene-7,12-dione 10a. Sequential aromatization, photooxidation and hydrolysis of the glucosyl unit gave (+)-3 (98% ee) in an 8% overall yield from 8.

Anthraquinones↗
PubMed2001

Evaluation of efficacy of school-based anthelmintic treatments against anaemia in children in the United Republic of Tanzania.

OBJECTIVE: To determine the impact of deworming on anaemia as part of a large-scale school-based anthelmintic treatment programme in the Tanga Region of the United Republic of Tanzania. METHODS: Both the reduction in the prevalence of anaemia and the cost per case prevented were taken into consideration. Cross-sectional studies involved parasitological examination and anaemia evaluation before and at 10 months and 15 months after schoolchildren were dewormed. FINDINGS: Baseline studies indicated that the prevalence of anaemia (haemoglobin < 110 g/l) was high (54%) among schoolchildren, particularly those with high intensities of hookworm and schistosomiasis. Attributable fraction analysis suggested that hookworm and schistosomiasis were responsible for 6% and 15% of anaemia cases, respectively. Fifteen months after deworming with albendazole and praziquantel the prevalence of anaemia was reduced by a quarter and that of moderate-to-severe anaemia (haemoglobin <90 g/l) was reduced by nearly a half. The delivery of these anthelmintics through the school system was achieved at the relatively low cost of US$ 1 per treated child. The cost per anaemia case prevented by deworming schoolchildren was in the range US$ 6-8, depending on the haemoglobin threshold used. CONCLUSIONS: The results suggested that deworming programmes should be included in public health strategies for the control of anaemia in schoolchildren where there are high prevalences of hookworm and schistosomiasis.

Albendazole↗
PubMed2001

Predicting the distribution of urinary schistosomiasis in Tanzania using satellite sensor data.

In this paper, remotely sensed (RS) satellite sensor environmental data, using logistic regression, are used to develop prediction maps of the probability of having infection prevalence exceeding 50%, and warranting mass treatment according to World Health Organization (WHO) guidelines. The model was developed using data from one area of coastal Tanzania and validated with independent data from different areas of the country. Receiver operating characteristic (ROC) analysis was used to evaluate the model's predictive performance. The model allows reasonable discrimination between high and low prevalence schools, at least within those geographical areas in which they were originally developed, and performs reasonably well in other coastal areas, but performs poorly by comparison in the Great Lakes area of Tanzania. These results may be explained by reference to an ecological zone map based on RS-derived environmental data. This map suggests that areas where the model reliably predicts a high prevalence of schistosomiasis fall within the same ecological zone, which has common intermediate-host snail species responsible for transmission. By contrast, the model's performance is poor near Lake Victoria, which is in a different ecological zone with different snail species. The ecological map can potentially define a template for those areas where existing models can be applied, and highlight areas where further data and models are required. The developed model was then used to provide estimates of the number of schoolchildren at risk of high prevalence and associated programme costs.

Adolescent↗
PubMed2001

Community perception of school-based delivery of anthelmintics in Ghana and Tanzania.

This paper presents the results of an evaluation of community perception of two large-scale, government-run, school-based health programmes delivering anthelmintic drugs to primary school children, in Ghana (80 442 children in 577 schools) and Tanzania (110 000 children in 352 schools). Most teachers (96% in Ghana and 98% in Tanzania) were positive about their role in the programme, including administration of anthelmintic drugs, and parents and children fully accepted their taking on this role. The benefits of the programme were apparent to teachers, parents and children in terms of improved health and well-being of the children. Over 90% of parents in both Ghana and Tanzania indicated a willingness to pay for the continuation of drug treatment. The evaluation also highlighted areas that are critical to programme effectiveness, such as communication between schools and parents, the issue of collaboration between the health and education sectors, parents' perception of the importance of helminth infection as a serious and chronic health problem (compared with more acute and life threatening illnesses such as malaria), and who should pay for treatment of side-effects.

Adult↗
PubMed2001

What is the prevalence of symptomatic or asymptomatic femoral head osteonecrosis in patients previously treated with chemoradiation? A magnetic resonance study of anal cancer patients.

It is generally assumed that femoral head osteonecrosis (FHO) is a serious but rare complication of pelvic radiotherapy. A review of the literature carried out by the authors indicates a prevalence of 4/763 (95% confidence interval 0.1%-1.3%). A recent publication has suggested that the prevalence of symptomatic FHO may be much greater than previously assumed as a result of sensitization of bone to radiation by concomitant treatment with chemotherapy. Magnetic resonance imaging (MRI) is currently the most sensitive modality for detecting and confirming symptomatic or asymptomatic FHO of any aetiology. The aim of this study therefore was to assess the prevalence of symptomatic and asymptomatic FHO in patients previously treated for anal cancer by chemoradiation (CRT). The hips of 34 currently disease-free individuals (11 men and 23 women; median age 67 years, range 32-86) were scanned using a coronal T1-weighted sequence. The images were assessed for evidence of FHO. The median time of scanning after the end of CRT was 35 months (range 6-107). No cases (0/34) of symptomatic or asymptomatic FHO were detected in these patients. Given the established sensitivity of MRI in the detection of FHO, it is concluded that changes indicative of osteonecrosis were uncommon after CRT in the current cohort of patients. Recent evidence from the literature suggests, however, that elderly females are at greatest risk of developing FHO after CRT.

Adult↗
PubMed2001

Anaemia in schoolchildren in eight countries in Africa and Asia.

OBJECTIVE: To report on the haemoglobin concentrations and prevalence of anaemia in schoolchildren in eight countries in Africa and Asia. DESIGN: Blood samples were collected during surveys of the health of schoolchildren as a part of programmes to develop school-based health services. SETTING: Rural schools in Ghana, Indonesia, Kenya, Malawi, Mali, Mozambique, Tanzania and Vietnam. SUBJECTS: Nearly 14 000 children enrolled in basic education in three age ranges (7-11 years, 12-14 years and > or =15 years) which reflect the new UNICEF/WHO thresholds to define anaemia. RESULTS: Anaemia was found to be a severe public health problem (defined as >40% anaemic) in five African countries for children aged 7-11 years and in four of the same countries for children aged 12-14 years. Anaemia was not a public health problem in the children studied in the two Asian countries. More boys than girls were anaemic, and children who enrolled late in school were more likely to be anaemic than children who enrolled closer to the correct age. The implications of the four new thresholds defining anaemia for school-age children are examined. CONCLUSIONS: Anaemia is a significant problem in schoolchildren in sub-Saharan Africa. School-based health services which provide treatments for simple conditions that cause blood loss, such as worms, followed by multiple micronutrient supplements including iron, have the potential to provide relief from a large burden of anaemia.

Adolescent↗
PubMed2001

The potential of rapid screening methods for Schistosoma mansoni in western Kenya.

Data from 46 schools in western Kenya were used to investigate the performance of school-based questionnaires, on reported blood in stool and water-contact patterns, as indicators of the prevalence of human infection with Schistosoma mansoni. Prevalence of infection was associated with the prevalence of self-reported blood in stool, recent history of swimming and recent history of fishing. It was shown that use of a threshold of 30% of subjects reporting blood in stool would identify 42.9% of the 'high-prevalence' schools (i.e. prevalence > or = 50%) and 87.5% of the 'low-prevalence' schools (i.e. prevalence < 50%). A threshold of 25% reporting swimming would identify 57.1% and 93.7% of the high- and low-prevalence schools, respectively. Blood in stool appears to be too coarse an indicator to identify schools for mass treatment correctly. Although the use of multiple questions improved the diagnostic performance of the questionnaire in identifying the high-prevalence schools, it was unclear how questions can best be combined in other settings. However, there is a direct relationship between prevalence of S. mansoni infection and distance of the school from the lakeshore; analysis indicated that use of a threshold of 5 km from the lakeshore would correctly identify most (90%) of both the low- and high-prevalence schools. Distance to the lakeshore may therefore be used to screen schools in much of East Africa (i.e. those areas close to the Great Lakes where the infection is known to be prevalent and where much of the region's population is concentrated). In other areas of transmission, such as irrigation areas, further studies are still required.

Adolescent↗
PubMed2001

Foods found in the wild around nuclear sites: an evaluation of radiological impact.

Habit surveys were carried out around four licensed nuclear sites to identify people who collect foodstuffs from the wild (so-called 'free foods'). In total, around 800 collectors were readily identified, most of whom collected more than one free food. The data indicated that estimates of higher than average doses could reasonably be based on the three foodstuffs of most importance. Foods were selected for further study on the basis of either the number of collectors or the amount consumed. The radionuclides of interest were identified using published information on the discharges from each site. The resultant average and higher than average doses were estimated using the site-specific habit data. For all sites, doses from the consumption of free foods were low and of no radiological importance. Assessments based solely on data for cultivated foods would not therefore have underestimated radiological impact significantly. However, given the wide utilisation of free foods found in this study, for rigorous assessments it would be prudent to take account of the consumption of foods from the wild.

England↗
PubMed2000

A Grid Complex

Explore the source record for details and available documents.

Journal Article↗
PubMed2000

The potential of geographical information systems and remote sensing in the epidemiology and control of human helminth infections.

Geographic information systems (GIS) and remote sensing (RS) technologies are being used increasingly to study the spatial and temporal patterns of infectious diseases. For helminth infections, however, such applications have only recently begun despite the recognition that infection distribution patterns in endemic areas may have profound effects on parasite population dynamics and therefore the design and implementation of successful control programmes. Here, we review the early applications of these technologies to the major human helminths (geohelminths, schistosomes and the major lymphatic filarial worms), which demonstrate the potential of these tools to serve as: (1) an effective data capture, mapping and analysis tool for the development of helminth atlases; (2) an environment for modeling the spatial distribution of infection in relation to RS and environmental variables, hence furthering the understanding of the impact of density-independent factors in underlying observed parasite spatial distributions and their effective prediction; and (3) a focal tool in parasite control programming given their abilities to (i) better define endemic areas, (ii) provide more precise estimates of populations-at-risk, (iii) map their distribution in relation to health facilities and (iv) by facilitating the stratification of areas by infection risk probabilities, to aid in the design of optimal drug or health measure delivery systems. These applications suggest a successful role for GIS/RS applications in investigating the spatial epidemiology of the major human helminths. It is evident that further work addressing a range of critical issues include problems of data quality, the need for a better understanding of the population biological impact of environmental factors on critical stages of the parasite life-cycle, the impacts and consequences of spatial scale on these relationships, and the development and use of appropriate spatially-explicit statistical and modeling techniques in data analysis, is required if the true potential of this tool to helminthology is to be fully realized.

Animals↗
PubMed2000

Towards an atlas of human helminth infection in sub-Saharan Africa: the use of geographical information systems (GIS).

The value of a geographical perspective to infectious disease epidemiology and control has long been recognized. However, the labour required to produce maps, and keep them up to date, has inhibited the development of this area, and very little is currently known about the spatial distribution of parasitic infections other than malaria, trypanosomiasis and onchocerciasis. A recent initiative by an international group of collaborators is attempting to redress the absence of detailed spatial information on the major helminth infections of humans. In this article, Simon Brooker and colleagues describe progress made by this initiative in mapping helminth infections in sub-Saharan Africa, highlighting the value as well as the limitations of this empirical mapping approach.

Africa South of the Sahara↗
PubMed2000

Age patterns in stunting and anaemia in African schoolchildren: a cross-sectional study in Tanzania.

OBJECTIVE: To describe the nutritional status of schoolchildren from a rural area of Tanzania, with a particular emphasis on older adolescents to determine the timing of the growth spurt and differences by sex. DESIGN: A cross-sectional survey using a randomly selected sample. SUBJECTS: Six thousand eight hundred and one children aged 7-18 y randomly selected from those enrolled in standards 2-5 in 59 primary schools in Magu District, Tanzania. RESULTS: Overall, 52.5% of children were stunted and 43.0% were underweight, with significantly more boys stunted and underweight than girls. Z-scores of height-for-age for both boys and girls decreased progressively between 7 and 12 y. After 12 y the height-for-age z-scores of girls show a marked upturn, whilst z-scores for boys continue to decrease throughout the school-aged years until 16 y when a slight upturn is observed. Anaemia (Hb<120 g/L) was present in 62.6% of children, with the prevalence decreasing with age. Anaemia improved throughout the school years for boys, but did not for girls. Age, sex and hookworm infection were significant predictors of anaemia. CONCLUSION: Stunting and anaemia are exceptionally common conditions in African schoolchildren. The findings highlight important differences between boys and girls, which are suggestive of compensatory growth at 12 y for girls and at 16 y for boys, although it remains unclear whether boys will catch up in height at older ages. SPONSORSHIP: Funding was provided by the Wellcome Trust. European Journal of Clinical Nutrition (2000) 54, 36-40

Adolescent↗
PubMed1999

Can prevalence of infection in school-aged children be used as an index for assessing community prevalence?

Community data on the prevalence of helminth infections is important for guiding health policy, but expensive to collect. As a result most surveys focus on school-aged children, frequently using schools as a sentinel population. Since there already exists a vast amount of data on infection levels in school-aged children, but limited community-based data, we undertook a literature search on age-stratified infection data for intestinal nematode infections and schistosomiasis in Africa, to investigate whether estimates of the prevalence of infection in school-aged children could provide an index for determining community prevalence. The observed data on prevalence of infection in infants, school-aged children and adults were fitted using linear and logistic regression models which take into account variation in sample prevalences. Despite the wide variation in study sites, the observed relationship between community prevalence and school-aged prevalence was remarkably consistent for each parasite species. The prevalence of infection in school-aged children alone was shown to be higher than the predicted prevalence in the community, but the degree of overestimation was dependent on the parasite species and the level of infection. The results suggest that the prevalence of infection in school-aged children could provide a cost-effective predictive tool which can be used at a district/national level to identify target areas for control and to evaluate the numbers at risk of infection.

Adolescent↗
PubMed1999

The performance of school-based questionnaires of reported blood in urine in diagnosing Schistosoma haematobium infection: patterns by age and sex.

This study investigates the performance of school-based questionnaires of reported blood in urine as an indicator of the prevalence of Schistosoma haematobium infection in schools and the presence of infection in individuals. In most schools (87%), the prevalence of reported blood in urine underestimates the prevalence of S. haematobium infection. Predictive value analysis suggests that a threshold of 30% reported blood in urine would identify most of the high prevalence schools (i.e. those with 50% or more children infected with S. haematobium). Although the prevalence of S. haematobium infection was greater in males than females, girls reported a lower prevalence of blood in urine than boys even at comparable levels of infection. Reported blood in urine in females was more specific (identifying 10% more uninfected girls than the sign in boys), but was far less sensitive (identifying less than 20% of infected girls than boys). The sensitivity of reported blood in urine was also related to age, being significantly lower in girls over 14 years of age. The proportion of infected children who reported blood in urine was also lower in schools where the prevalence of reported blood in urine is less than 30%. The results suggest that the selective treatment of children based on reported blood in urine in low prevalence schools would miss a high proportion of infected children, particularly girls. It remains unclear whether other rapid assessment techniques, such as the use of reagent strips, would offer greater cost-effectiveness.

Adolescent↗
PubMed1995

Spurious ST segment depression by automated ST segment analysis.

Perioperative myocardial ischemia has been shown to be predictive of adverse cardiac outcome [1]. One method of detecting intraoperative myocardial ischemia is automated ST segment monitoring [2]. The rationale behind automated ST monitoring is that the clinician will be promptly alerted to ischemic changes in the ECG. This may lead to earlier intervention and, perhaps, improved outcome [3]. We describe a case in which automated ST segment monitoring falsely signaled the presence of intraoperative ST segment depression. This event emphasizes the importance of confirming the validity of ST segment changes before instituting therapy.

Aged↗