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Latest Paper:
ABSTRACT: Effective malaria control requires information on both the geographical distribution of malaria risk and the effectiveness of malaria interventions. The current standard for estimating malaria infection and impact indicators are household cluster surveys, but their complexity and expense preclude frequent and decentralized monitoring. This paper reviews the historical experience and current rationale for the use of schools and school children as a complementary, inexpensive framework for planning, monitoring and evaluating malaria control in Africa. Consideration is given to (i) the selection of schools;(ii) diagnosis of infection in schools;(iii) the representativeness of schools as a proxy of the communities they serve; and (iv) the increasing need to evaluate interventions delivered through schools. Finally, areas requiring further investigation are highlighted.
ABSTRACT: BACKGROUND: The scaling of malaria control to achieve universal coverage requires a better understanding of the population sub-groups that are least protected and provide barriers to interrupted transmission. Here we examine the age pattern of use of insecticide treated nets (ITNs) in Africa in relation to biological vulnerabilities and the implications for future prospects for universal coverage. METHODS: Recent national household survey data for 18 malaria endemic countries in Africa were assembled to indentify information on use of ITNs by age and sex. Age-structured medium variant projected population estimates for the mid-point year of the earliest and most recent national surveys were derived to compute the population by age protected by ITNs. RESULTS: All surveys were undertaken between 2005 and 2009, either as demographic health surveys (n=12) or malaria indicator surveys (n=6). Countries were categorized into three ITN use groups: <10%; 10 to <20%; and [greater than or equal to]20% and projected population estimates for the mid-point year of 2007 were computed. In general, the pattern of overall ITNs use with age was similar by country and across the three country groups with ITNs use initially high among children <5 years of age, sharply declining among the population aged 5-19 years, before rising again across the ages 20-44 years and finally decreasing gradually in older ages. For all groups of countries, the highest proportion of the population not protected by ITNs (38%- 42%) was among those aged 5-19 years. CONCLUSION: In malaria-endemic Africa, school-aged children are the least protected with ITNs but represent the greatest reservoir of infections. With increasing school enrollment rates, school-delivery of ITNs should be considered as an approach to reach universal ITNs coverage and improve the likelihood of impacting upon parasite transmission.
1School of Exercise and Nutrition Sciences, Deakin University, Burwood, Victoria, AUSTRALIA; 2School of Human Movement Studies, Queensland University of Technology, Kelvin Grove, Queensland, AUSTRALIA; 3Department of Physiology, The University of Melbourne, Parkville, Victoria, AUSTRALIA; 4School of Exercise, Biomedical and Health Sciences, Edith Cowan University, Joondalup, AUSTRALIA; 5Department of Physiology, Australian Institute of Sport, Belconnen, Australian Capital Territory, AUSTRALIA; and 6Division of Materials Science and Engineering, Commonwealth Scientific and Industrial Research Organisation, Belmont, Victoria, AUSTRALIA.
PURPOSE:: To examine the influence of two different fast-start pacing strategies on performance and oxygen consumption (V O2) during cycle ergometer time trials lasting approximately 5 min. METHODS:: Eight trained male cyclists performed four cycle ergometer time trials whereby the total work completed (113 +/- 11.5 kJ; mean +/- SD) was identical to the better of two 5-min self-paced familiarization trials. During the performance trials, initial power output was manipulated to induce either an all-out or a fast start. Power output during the first 60 s of the fast-start trial was maintained at 471. +/- 48. W, whereas the all-out start approximated a maximal starting effort for the first 15 s (mean power: 753.6 +/- 76.5 W) followed by 45 s at a constant power output (376.8 +/- 38.5 W). Irrespective of starting strategy, power output was controlled so that participants would complete the first quarter of the trial (28.3 +/- 2.9 kJ) in 60 s. Participants performed two trials using each condition, with their fastest time trial compared. RESULTS:: Performance time was significantly faster when cyclists adopted the all-out start (4 min 48 s +/- 8 s) compared with the fast start (4 min 51 s +/- 8 s; P < .05). The first-quarter V O2 during the all-out start trial (3.4 +/- .4 L.min) was significantly higher than during the fast-start trial (3.1 +/- .4 L.min; P < .05). After removal of an outlier, the percentage increase in first-quarter V O2 was significantly correlated (r =- .86, P < .05) with the relative difference in finishing time. CONCLUSIONS:: An all-out start produces superior middle distance cycling performance when compared with a fast start. The improvement in performance may be due to a faster V O2 response rather than time saved due to a rapid acceleration.
School of Exercise and Nutrition Sciences, Deakin University, Burwood, VIC.
The importance of pacing for middle-distance performance is well recognized, yet previous research has produced equivocal results. Twenty-six trained male cyclists (VO(2peak) 62.8 +/- 5.9 ml . kg(-1). min(-1); maximal aerobic power output 340 +/- 43 W; mean +/- s) performed three cycling time-trials where the total external work (102.7 +/- 13.7 kJ) for each trial was identical to the best of two 5-min habituation trials. Markers of aerobic and anaerobic metabolism were assessed in 12 participants. Power output during the first quarter of the time-trials was fixed to control external mechanical work done (25.7 +/- 3.4 kJ) and induce fast-, even-, and slow-starting strategies (60, 75, and 90 s, respectively). Finishing times for the fast-start time-trial (4:53 +/- :11 min:s) were shorter than for the even-start (5:04 +/- :11 min:s; 95% CI = 5 to 18 s, effect size = .65, P < .001) and slow-start time-trial (5:09 +/- :11 min:s; 95% CI = 7 to 24 s, effect size = 1.00, P < .001). Mean VO(2) during the fast-start trials (4.31 +/- .51 litres . min(-1)) was .18 +/- .19 litres . min(-1)(95% CI = .07 to .30 litres . min(-1), effect size = .94, P = .003) higher than the even- and .18 +/- .20 litres . min(-1)(95% CI = .5 to .30 litres . min(-1), effect size = .86, P = .007) higher than the slow-start time-trial. Oxygen deficit was greatest during the first quarter of the fast-start trial but was lower than the even- and slow-start trials during the second quarter of the trial. Blood lactate and pH were similar between the three trials. In conclusion, performance during a 5-min cycling time-trial was improved with the adoption of a fast- rather than an even- or slow-starting strategy.
Department of Obstetrics and Gynecology, School of Medical Sciences, Universidade de Campinas, Campinas, São Paulo, Brazil. ehardy@uol.com.br
BACKGROUND: Several studies suggest that many women would prefer to avoid menses altogether, but few studies have examined the social or clinical predictors of such preference. STUDY DESIGN: In total, 1224 healthy women of reproductive age were surveyed in Brazil, Germany and the United States regarding social, menstrual and reproductive characteristics and preferences for various dimensions of menstruation, including the ideal interval between menses. The extent to which a preference to never bleed was predicted by current experiences with menses was evaluated. RESULTS: Long menses, menstrual pain and a perceived high cost of pads and tampons were predictive of preferring amenorrhea over all other menstrual patterns after controlling for age, parity and education. Independent significant associations were also found with increasing degrees of life stress and ever use of injectable contraceptives. CONCLUSION: A negative experience with menstruation, a high ranking of life stress and ever use of injectable contraception were independently associated with a preference to avoid menses altogether.
ABSTRACT: BACKGROUND: Clinical malaria has proven an elusive burden to enumerate. Many cases go undetected by routine disease recording systems. Epidemiologists have, therefore, frequently defaulted to actively measuring malaria in population cohorts through time. Measuring the clinical incidence of malaria longitudinally is labour-intensive and impossible to undertake universally. There is a need, therefore, to define a relationship between clinical incidence and the easier and more commonly measured index of infection prevalence: the "parasite rate". This relationship can help provide an informed basis to define malaria burdens in areas where health statistics are inadequate. METHODS: Formal literature searches were conducted for Plasmodium falciparum malaria incidence surveys undertaken prospectively through active case detection at least every 14 days. The data were abstracted, standardized and geo-referenced. Incidence surveys were time-space matched with modelled estimates of infection prevalence derived from a larger database of parasite prevalence surveys and modelling procedures developed for a global malaria endemicity map. Several potential relationships between clinical incidence and infection prevalence were then specified in a non-parametric Gaussian process model with minimal, biologically informed, prior constraints. Bayesian inference was then used to choose between the candidate models. RESULTS: The suggested relationships with credible intervals are shown for the Africa and a combined America and Central and South East Asia regions. In both regions clinical incidence increased slowly and smoothly as a function of infection prevalence. In Africa, when infection prevalence exceeded 40%, clinical incidence reached a plateau of 500 cases per thousand of the population per annum. In the combined America and Central and South East Asia regions, this plateau was reached at 250 cases per thousand of the population per annum. A temporal volatility model was also incorporated to facilitate a closer description of the variance in the observed data. CONCLUSION: It was possible to model a relationship between clinical incidence and P. falciparum infection prevalence but the best-fit models were very noisy reflecting the large variance within the observed opportunistic data sample. This continuous quantification allows for estimates of the clinical burden of P. falciparum of known confidence from wherever an estimate of P. falciparum prevalence is available.
ABSTRACT: BACKGROUND: Understanding spatio-temporal variation in malaria incidence provides a basis for effective disease control planning and monitoring. METHODS: Monthly surveillance data between 1991 and 2006 for Plasmodium vivax and Plasmodium falciparum malaria across 128 counties were assembled for Yunnan, a province of China with one of the highest burdens of malaria. County-level Bayesian Poisson regression models of incidence were constructed, with effects for rainfall, maximum temperature and temporal trend. The model also allowed for spatial variation in county-level incidence and temporal trend, and dependence between incidence in June-September and the preceding January-February. RESULTS: Models revealed strong associations between malaria incidence and both rainfall and maximum temperature. There was a significant association between incidence in June-September and the preceding January-February. Raw standardised morbidity ratios showed a high incidence in some counties bordering Myanmar, Laos and Vietnam, and counties in the Red River valley. Clusters of counties in south-western and northern Yunnan were identified that had high incidence not explained by climate. The overall trend in incidence decreased, but there was significant variation between counties. CONCLUSIONS: Dependence between incidence in summer and the preceding January-February suggests a role of intrinsic host-pathogen dynamics. Incidence during the summer peak might be predictable based on incidence in January-February, facilitating malaria control planning, scaled months in advance to the magnitude of the summer malaria burden. Heterogeneities in county-level temporal trends suggest that reductions in the burden of malaria have been unevenly distributed throughout the province.
ABSTRACT: BACKGROUND: In sub-Saharan Africa, knowledge of malaria transmission across rapidly proliferating urban centres and recommendations for its prevention or management remain poorly defined. This paper presents the results of an investigation into infection prevalence and treatment of recent febrile events among a slum population in Nairobi, Kenya. METHODS: In July 2008, a community-based malaria parasite prevalence survey was conducted in Korogocho slum, which forms part of the Nairobi Urban Health and Demographic Surveillance system. Interviewers visited 1,069 participants at home and collected data on reported fevers experienced over the preceding 14 days and details on the treatment of these episodes. Each participant was tested for malaria parasite presence with Rapid Diagnostic Test (RDT) and microscopy. Descriptive analyses were performed to assess the period prevalence of reported fever episodes and treatment behaviour. RESULTS: Of the 1,069 participants visited, 983 (92%) consented to be tested. Three were positive for Plasmodium falciparum using RDT; however, all were confirmed negative on microscopy. Microscopic examination of all 953 readable slides showed zero prevalence. Overall, from the 1,004 participants who have data on fever, 170 fever episodes were reported giving a relatively high period prevalence (16.9%, 95% CI:13.9%-20.5%) and higher among children below five years (20.1%, 95%CI:13.8%-27.8%). Of the fever episodes with treatment information 54.3%(95%CI:46.3%-62.2%) were treated as malaria using mainly sulphadoxine-pyrimethamine or amodiaquine, including those managed at a formal health facility. Only four episodes were managed using the nationally recommended first-line treatment, artemether-lumefantrine. CONCLUSION: The study could not demonstrate any evidence of malaria in Korogocho, a slum in the centre of Nairobi. Fever was a common complaint and often treated as malaria with anti-malarial drugs. Strategies, including testing for malaria parasites to reduce the inappropriate exposure of poor communities to expensive anti-malarial drugs provided by clinical services and drug vendors, should be a priority for district planners.
Simon Brooker,
Narcis Kabatereine,
Jennifer Smith,
Denise Mupfasoni,
Mariam Mwanje,
Onesime Ndayishimiye,
Nicholas Lwambo,
Deborah Mbotha,
Peris Karanja,
Charles Mwandawiro,
Eric Muchiri,
Archie Clements,
Donald Bundy,
Robert Snow
ABSTRACT: BACKGROUND: Reliable and updated maps of helminth (worm) infection distributions are essential to target control strategies to those populations in greatest need. Although many surveys have been conducted in endemic countries, the data are rarely available in a form that is accessible to policy makers and the managers of public health programmes. This is especially true in sub-Saharan Africa, where empirical data are seldom in the public domain. In an attempt to address the paucity of geographical information on helminth risk, this article describes the development of an updated global atlas of human helminth infection, showing the example of East Africa. METHODS: Empirical, cross-sectional estimates of infection prevalence conducted since 1980 were identified using electronic and manual search strategies of published and unpublished sources. A number of inclusion criteria were imposed for identified information, which was extracted into a standardized database. Details of survey population, diagnostic methods, sample size and numbers infected with schistosomes and soil-transmitted helminths were recorded. A unique identifier linked each record to an electronic copy of the source document, in portable document format. An attempt was made to identify the geographical location of each record using standardized geolocation procedures and the assembled data were incorporated into a geographical information system. RESULTS: At the time of writing, over 2,748 prevalence surveys were identified through multiple search strategies. Of these, 2,612 were able to be geolocated and mapped. More than half (58%) of included surveys were from grey literature or unpublished sources, underlining the importance of reviewing in-country sources. 66% of all surveys were conducted since 2000. Comprehensive, countrywide data are available for Burundi, Rwanda and Uganda. In contrast, information for Kenya and Tanzania is typically clustered in specific regions of the country, with few records from areas with very low population density and/or environmental conditions which are unfavourable for helminth transmission. Information is presented on the prevalence and geographical distribution for the major helminth species. CONCLUSIONS: For all five countries, the information assembled in the current atlas provides the most reliable, up-to-date and comprehensive source of data on the distribution of common helminth infections to guide the rational implementation of control efforts.
ABSTRACT: BACKGROUND: Creatine synthesis takes place predominately in the kidney and liver via a two-step process involving AGAT (L-arginine:glycine amidinotransferase) and GAMT (guanidinoacetate methyltransferase). Creatine is taken into cells via the creatine transporter (CrT), where it plays an essential role in energy homeostasis, particularly for tissues with high and fluctuating energy demands. Very little is known of the fetal requirement for creatine and how this may change with advancing pregnancy and into the early neonatal period. Using the spiny mouse as a model of human perinatal development, the purpose of the present study was to comprehensively examine the development of the creatine synthesis and transport systems. RESULTS: The estimated amount of total creatine in the placenta and brain significantly increased in the second half of pregnancy, coinciding with a significant increase in expression of CrT mRNA. In the fetal brain, mRNA expression of AGAT increased steadily across the second half of pregnancy, although GAMT mRNA expression was relatively low until 34 days gestation (term is 38-39 days). In the fetal kidney and liver, AGAT and GAMT mRNA and protein expression were also relatively low until 34-37 days gestation. Between mid-gestation and term, neither AGAT or GAMT mRNA or protein could be detected in the placenta. CONCLUSIONS: Our results suggest that in the spiny mouse, a species where, like the human, considerable organogenesis occurs before birth, there appears to be a limited capacity for endogenous creatine synthesis until approximately .9 of pregnancy. This implies that a maternal source of creatine, transferred across the placenta, may be essential until the creatine synthesis and transport system matures in preparation for birth. If these results also apply to the human, premature birth may increase the risk of creatine deficiency.
