Blanket Mass Research Articles

Urogenital schistosomiasis among pre-school and school aged children in four districts of north western Tanzania after 15 years of mass drug administration: Geographical prevalence, risk factors and performance of haematuria reagent strips.

Urogenital schistosomiasis remains as a public health problem in Tanzania and for the past 15 years, mass drug administration (MDA) targeting primary school children has remained as the mainstay for its control. However, after multiple rounds of MDA in highly risk groups, there are no data on the current status of Schistosoma haematobium in known endemic areas. Furthermore, the performance of commonly used diagnostic test, the urine reagent strips is not known after the decline in prevalence and intensities of infection following repeated rounds of treatment. Thus, after 15 of national MDA, there is a need to review the strategy and infection diagnostic tools available to inform the next stage of schistosomiasis control in the country. A analytical cross-sectional study was conducted between October and November, 2019 among pre-school (3-5years old) and school aged children (6-17 years old) living in four (4) districts with low (<10%) and moderate (10%-<50%) endemicity for schistosomiasis as per WHO classification at the start of the national control programme in 2005/06, with mean prevalence of 20.7%. A total of 20,389 children from 88 randomly selected primary schools participated in the study. A questionnaire was used to record demographic information. A single urine sample was obtained from each participant and visually examined for macrohaematuria, tested with a dipstick for micro-haematuria, to determine blood in urine; a marker of schistosome related morbidity and a proxy of infection. Infection intensity was determined by parasitological examination of the urine sample for S. haematobium eggs. Overall, mean infection prevalence was 7.4% (95%CI: 7.0-7.7, 1514/20,389) and geometric mean infection intensity was 15.8eggs/10mls. Both infection prevalence (5.9% versus 9%, P<0.001) and intensity (t = -6.9256, P<0.001) were significantly higher in males compared to females respectively. Light and heavy infections were detected in 82.3% and 17.7% of the positive children respectively. The prevalence of macrohaematuria was 0.3% and that of microhaematuria was 9.3% (95%CI:8.9-9.7). The sensitivity and specificity of the urine reagent strip were 78% (95%CI: 76.1-79.9) and 99.8% (95%CI: 99.7-99.9). Having light (P<0.001) and heavy infection intensities (P<0.001) and living in the study districts increased the odd of having microhaematuria. Predictors of S. haematobium infection were being male (P<0.003), microhaematuria (P<0.001), and living in the three study districts (P<0.001) compared to living at Nzega district. The findings provide an updated geographical prevalence which gives an insight on the planning and implementation of MDA. Comparing with the earlier mapping survey at the start of the national wide mass drug administration, the prevalence of S. haematobium infection have significantly declined. This partly could be attributed to repeated rounds of mass drug administration. The urine reagent strips remain as a useful adjunct diagnostic test for rapid monitoring of urogenital schistosomiasis in areas with low and high prevalence. Based on prevalence levels and with some schools having no detectable infections, review of the current blanket mass drug administration is recommended.

Space Environmental Testing of Novel Candidate Materials for Multilayer Insulation

Multilayer insulation forms the outer barrier of a satellite towards space. Polymer foils used in multilayer insulation have to withstand the space environment for mission durations often lasting well above 10 years. This paper outlines the space environmental test campaign performed to qualify novel and advanced polymer foils to reduce blanket mass and replace export-controlled materials. Complete multilayer insulation layups were irradiated; these were composed of thicker outermost layers of the reference material Kapton®, a white polyimide and an alternative, conductive black polyimide and up to seven thin internal, aluminized or polyethylene terephthalate and polyethylene naphthalate layers separated by nonwoven spacers. One sample set consisted of polyether-ether-ketone foil and internal vacuum-deposited-aluminum-coated polyether-ether-ketone layers. Materials were exposed to ultraviolet, electrons and protons simulating a 15-year geostationary orbit mission. Absorptance was measured at various stages in situ during the exposures, and emittance was measured ex situ at the beginning and end of the test. With tensile testing, exposure influence on foil mechanical properties was determined and compared with pristine and reference materials. Although the white polyimide was sensitive to ultraviolet and showed strong degradation after ultraviolet and proton exposure, degradation of all other materials was within expected limits and compatible to state-of-the-art foils.

Protecting sources: from shield laws to Wikileaks

This paper focuses on recent developments in the right and ability of journalists to protect their sources’ anonymity in the United Kingdom, particularly in light of the Snowden revelations of June 2013, and the significance of collaboration between the global online media organization Wikileaks and mainstream news organisations. It explores two key difficulties faced by journalists: the notion of a qualified professional privilege and the unknown extent of covert requests by public authorities for disclosure involving communications data and metadata. In doing so, it comments upon the opening filled by Wikileaks, which protects its sources’ anonymity through high data security and encryption. This paper’s findings tend to show that the covert practice of blanket mass digital surveillance of individual communications including journalists’ is undermining source protection and the rise of Wikileaks as an alternative model is challenging the traditional role of journalists as mediators and gatekeepers in the digital era.

Planning long lasting insecticide treated net campaigns: should households’ existing nets be taken into account?

BackgroundMass distribution of long-lasting insecticide treated bed nets (LLINs) has led to large increases in LLIN coverage in many African countries. As LLIN ownership levels increase, planners of future mass distributions face the challenge of deciding whether to ignore the nets already owned by households or to take these into account and attempt to target individuals or households without nets. Taking existing nets into account would reduce commodity costs but require more sophisticated, and potentially more costly, distribution procedures. The decision may also have implications for the average age of nets in use and therefore on the maintenance of universal LLIN coverage over time.MethodsA stochastic simulation model based on the NetCALC algorithm was used to determine the scenarios under which it would be cost saving to take existing nets into account, and the potential effects of doing so on the age profile of LLINs owned. The model accounted for variability in timing of distributions, concomitant use of continuous distribution systems, population growth, sampling error in pre-campaign coverage surveys, variable net ‘decay’ parameters and other factors including the feasibility and accuracy of identifying existing nets in the field.ResultsResults indicate that (i) where pre-campaign coverage is around 40% (of households owning at least 1 LLIN), accounting for existing nets in the campaign will have little effect on the mean age of the net population and (ii) even at pre-campaign coverage levels above 40%, an approach that reduces LLIN distribution requirements by taking existing nets into account may have only a small chance of being cost-saving overall, depending largely on the feasibility of identifying nets in the field. Based on existing literature the epidemiological implications of such a strategy is likely to vary by transmission setting, and the risks of leaving older nets in the field when accounting for existing nets must be considered.ConclusionsWhere pre-campaign coverage levels established by a household survey are below 40% we recommend that planners do not take such LLINs into account and instead plan a blanket mass distribution. At pre-campaign coverage levels above 40%, campaign planners should make explicit consideration of the cost and feasibility of accounting for existing LLINs before planning blanket mass distributions. Planners should also consider restricting the coverage estimates used for this decision to only include nets under two years of age in order to ensure that old and damaged nets do not compose too large a fraction of existing net coverage.

Experimental Investigation of Z-Pinch IFE Chamber Liquid Structure Response

Z-Pinch IFE chamber fluid mechanics can be studied using simulant fluids such as water in reduced scale facilities. The use of porous liquid and solid blanket materials provides the key to mitigating blast effects from fusion reaction. The UCB Vacuum Hydraulics Experiment (VHEX) was recently upgraded with a large, annular inlet nozzle system to produce an annular porous liquid curtains to study Z-Pinch IFE chamber response. Explosives experiments in VHEX studied the response of the liquid structure to the detonation of high explosive C-4. The experiments demonstrated that the crushing of porous liquid structures is effective in transferring momentum uniformly into the blanket mass. No significant high-speed jetting or spall was observed exiting the shocked liquid structure. Independent measurement of the transient pressure history, coupled with high-speed video of the blanket response and final velocity, will provide the basis to validate gas dynamics and blanket response models.

Attachment system for helium-cooled blanket of RF DEMO fusion reactor

The development of DEMO thermonuclear reactor is a part of Russian national program on the fusion process mastering. The DEMO-S (stationary thermonuclear reactor) should be the logic continuation of the ITER-type projects (pulse thermonuclear reactors) and the prototype for commercial power plants. DEMO reactor layout suggests to use the segmented blanket with mounting/dismounting procedure through the vacuum vessel vertical ports. Taking into account this layout the blanket attachment system has been developed and the present paper is devoted to this subject. The considered attachment system includes the lower and upper toroidal support assemblies which connect all the blanket segments in the enclosed ring. In it's turn the lower support assemblies attached to the vacuum vessel through the system of hinged support pillars. The heights of support pillars for inboard and outboard blankets are selected so that to indemnify the blanket massif thermal expansions in vertical and radial directions. The support pillars have been calculated on strength taking into account the electromagnetic loads from the plasma disruptions and blanket mass. The selection of high-strength chromium steel as a structural material for the support pillars could be considered as the results of strength analysis. The conclusions on the possibility to apply this attachment system for fusion reactor blanket and the critical issues are contained in this paper too.

Performance Scaling of Fusion Reactors Using the Deuterium-Tritium and Advanced Fuel Cycles

How the plasma stability index beta and the fusion power density influence three performance parameters of fusion reactors burning deuterium-tritium and four advanced fusion fuel cycles was determined. The performance parameters include the total power produced per unit length of the reactor, the mass per unit length, and the specific mass in kilograms per kilowatt. The scaling of these parameters with beta and fusion power density was examined for a common set of conservative engineering assumptions on the allowable wall loading limits, the maximum magnetic field existing in the plasma, the average blanket mass density, etc. It was found that one should employ an entirely different strategy for the design of an engineering test reactor (ETR), designed to test components under high wall loadings and neutron fluences, than one would employ in designing a power plant reactor intended to produce the cheapest possible thermal power. An ETR should not be merely a scaled-down power plant reactor, but should operate at substantially different values of beta and plasma power density, and in some circumstances even use a different confinement concept and fusion fuel cycle.

Epidemiological Studies On Ascaris Lumbricoides Reinfection In Rural Communities In Korea: 1. The Relationship Between Prevalence And Monthly Reinfection Rate.

The epidemiological relationship between the current prevalence and monthly reinfection rate of Ascaris lumbricoides was observed in rural communities in Korea by measns of blanket mass chemotherapy and worm collection for measurement of the prevalence and reinfection rates. During the period from 1975 to 1980, a total of 4,466 inhabitants in 10 different localities were treated with 10 mg/kg of pyrantel pamoate and 2 days' whole stools were collected from 2,547 inhabitants. The stools were examined for the presence of expelled adult and/or young worms, which represent the prevalence and reinfection rates for past 2 months respectively. After then, the obtained rates were correlated each other applying the time-prevalence curve proposed by Hayashi. It was observed that the prevalence (overall worm positive rate) and worm burden per individual ranged by areas from 13.6 to 72.3% and 1.4~10.2 respectively. The calculated monthly reinfection rates (X) (from young worm positive rates) according to areas were in the range, 2.6~16.2%, and clearly correlated with the current prevalence (Y) under the equation, Y=1-(1-X)(7.2) where 7.2 is time in month. The equation means that after one time mass chemotherapy the period needed to attain equilibrium of prevalence again would be about 7~8 months. And it is inferred that the majority of reinfected worms in human host turn over every 7~8 months.

Efficacy Of Mebendazole In Treatment And Control Of Trichuriasis In Korea.

Mebendazole was tested for its efficacy in individual treatment and mass control of Trichuris trichiura infection in Korea. The results were as follows: 1. The efficacy of mebendazole in 430 cases 3 weeks after treatment with mebendazole(100-1,200 mg) was not so satisfactory (15.0-64.0 and 24.6-95.2% in cure and egg reduction rates respectively). But it was observed that the higher the total dose of the drug the better the efficacy. 2. The egg positive rate of the inhabitants in mass control programme by 600 mg mebendazole decreased form 40.0 to 5.6 % during one year, May 1982-May 1983, by repeated blanket mass chemotherapy every 3 months (in conventional regimen), while the decrease was less marked or unrecognizable in 3-month (signle or two divided doses), 6-month, 12-month interval and placebo control groups. From the results, it was concluded that, although mebendazole was not highly effective in individual treatment of T. trichiura infection, it was fairly useful in mass cotrol, by repeated mass chemotherapy every 3 months.

Epidemiological Studies On Ascaris Lumbricoides Reinfection In Rural Communities In Korea II. Age-Specific Reinfection Rates And Familial Aggregation Of The Reinfected Cases.

Epidemiological studies on the reinfection pattern of Ascaris lumbricoides were undertaken by means of blanket mass chemotherapy and worm collection in a rural village in Korea, during 1977~1980. The study objectives were to determine the age(sex)-specific reinfection rate during 2, 4, 6 and 12 months through repeated mass chemotherapy with pyrantel pamoate, and to observe the familial aggregation tendency of the reinfected cases. The results obtained are as follows: 1. The age(sex)-reinfection curve revealed that the reinfection rate is much higher in younger individuals than in olders in all of 4 kinds of interval chemotherapy groups. The highest reinfection rate and the highest burden of reinfected worms were observed in preschool childen, followed by primary school students. Such fluctuation in the age-specific reinfection rates was more pronounced in males than in females. 2. There was noted a significant tendency of familial aggregation among the reinfected cases. It is suggested that reinfection occurs never randomly but preferably to the members of certain household families. From these reinfection analyses, it is inferred that the principal mode of A. lumbricoides transmission in the surveyed rural area is likely to be of 'dooryard type', in which case childen and certain family members are more preferably reinfected. It is also suggested that the preschool childen should be included in the primary targets of mass control programme.

Effect Of Two-Month Interval Mass Chemotherapy On The Reinfection Of Ascaris Lumbricoides In Korea.

Atrial to control reinfection cycle of Ascaris lumbricoides was made in a rural village in Korea by blocking the process of new egg production. Chemotherapy with pyrantel pamoate was repeated bimonthly in three hamlet groups, each consisted of 105~149 inhabitants of whole age group. In one hamlet (2.5 mg/kg dose) blanket mass treatment was repeated for 18 times from June 1977 to May 1980. In other two, 5.0 mg and 10.0 mg/kg dose groups, treatment was undertaken for 10 times from June 1977 until December 1987 and later reinfection patten was observed. Follow-up examination was made by whole-day stool collection for 2 days from each case after every treatment. The samples were examined both for eggs and worms, adult and immature young, of A. lumbricoides. The results obtained are summarized as follows: 1. The pre-treatment egg positive rate in Group A, B and C was 48.1, 45.3 an 37.8% respectively. 2. The lowest dose of pyrantel pamoate, 2.5 mg/kg was equally effective as higher doses in case of repeated use for reinfection control. 3. Among 4,311 pyrantel treatments, only 8 cases complained of side effects such as abdominal pain and diarrhea. 4. When the blanket mass chemotherapy was continued 18 times in Group A, all of the examined inhabitants were free from reinfection and egg production from 28th month (the 15th treatment) until the end of study period, for 8 months. 5. When the mass chemotherapy was stopped after 10 times, the egg positive rate returned gradually up to half of pre-treatment level within one year. 6. From the analysis of total 124 positive cases during the course of follow-up, it was revealed that the mass chemotherapy with 2-month interval was successful for the suppression of fertilized egg production. However, social factors such as infected immigrants or absentees were inevitably encountered and involved in the fertilized egg production. Summarizing the results, at least 28-30 months were needed to eradicate A. lumbricoides in the subjected area of Korea, by repeated blanket mass treatment bimonthly with a quarter dose of pyrantel pamoate. Furthermore, to lessen the social factors as a source of later reinfetion, the project area of control programme should be extended as wide as possible.

Seasonal Fluctuation Of Ascaris Reinfection Incidences In A Rural Korean Population

This study was undertaken to estimate the reinfection incidence of Ascaris lumbricoides after biannual blanket mass chemotherapy and to figure out the characteristic seasonal fluctuation pattern in a Korean rural village. A total of 612 residents from 4 Ri's of Hwasung Gun, Kyunggi Do, Korea was selected and divided into 6 groups according to hamlets, each of which consisted of about 100 inhabitants. Each group received blanket biannual mass chemotherapy with 10 mg/kg of pyrantel pamoate respectively in each month, during the period from April 1977 to September 1978(Group A-April and October 1977 and April 1978, Group B-May and November 1977 and May l978, and so on). 1. Beforehand Ascaris infection status was evaluated by examining eggs and worms expelled exactly after the first mass chemotherapy checked during the first 6 months and the reinfection incidences were estimated in follow-up examinations during next l2 months by the above two kinds of methods and by detection of young Ascaris positive cases. Young Ascaris was defined as worm shorter than l3 cm and lighter than 500 mg and considered to have introduced to human host during the period from the previous 2 months to 2 weeks. The results were summarized as follows: 1.Beforehand infection rate with Ascaris were 42.3% (34.4~50.6% by group) by egg detection and 46.2% (36.2~51.9% by group) by worm detection methods in average. Number of worms per infected case was 2.7 (1.5~4.2 by group) in average. 2. Reinfection rates estimated by egg detection ranged from 8.0 to 3l.5% (l6.9% in average) in the first follow-up period and from 14.0 to 20.0% (l7.5% in average) in the second follow-up. Seasonal fluctuation was found marked and there were roughly two peaks, of which the larger appeared from February to March and the smaller from August to September. 3. Reinfection rates by worm detection method ranged from 20.6 to 34.9%(25.7% in average) and from 14.3 to 21.9% (19.6% in average) in respective follow-up examinations. Seasonal fluctuation was also observed and the peak incidence appeared one month earlier than those made by egg positive conversion. Number of worms per infected case decreased to 1.6 in average in both follow-up. 4. Young Ascaris detection rates ranged from 6.0 to 12.9% (9.4% in average) and from 2.3 to 5.8% (3.8% in average) in respective follow-up. Seasonal fluctuation was also observed. From January to February, the positive rates were up to 12.9% and 12.7% respectively, which formed the higher peak. Lower one was observed during July to August. From the above results, the actual time of Ascaris reinfection were November to December for the higher peak and May to June for the lower one in Korean population. Pickled vegetable was suggested as a most probable source of Ascaris reinfection during late autumn to winter season.