379 research outputs found

    \ud Detection and Monitoring of Insecticide Resistance in Malaria Vectors in Tanzania Mainland\ud

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    \ud Vector control is a major component of the global strategy for malaria control which aims to prevent parasite transmission mainly through interventions targeting adult Anopheline vectors. Insecticide treated nets (ITNs) and indoor residual spraying (IRS) are the cornerstone of malaria vector control programmes. These major interventions in most cases use pyrethroid insecticides which are also used for agricultural purposes. With widespread development of resistance to pyrethroid insecticides in malaria vectors raises concern over the sustainability of insecticide-based interventions for malaria control. Therefore, close monitoring of performance of the insecticides against malaria vectors is essential for early detection and\ud management of resistance. To measure pyrethroid susceptibility in populations of malaria vectors in Tanzania and to test the efficacy of LLINs/ITNs and insecticide residues on sprayed wall substrates in the IRS operation areas. In 2011 the National Institute for Medical Research (NIMR) in collaboration with National Malaria Control Programme (NMCP) conducted large scale surveillance to determine the countrywide susceptibility levels of malaria vectors to insecticides used for both public health and agricultural purposes. Anopheles gambiae Giles s.l. were collected during national surveys and samples of LLINs/ITNs in the 14 sentinel sites and houses from the IRS areas were randomly selected for bioassays to test the efficacy and insecticide residual effects on sprayed wall substrates respectively. Wild adult mosquitoes for susceptibility testing were collected by resting catches indoors. Net traps (outdoors and indoors) were set up to enhance catches. WHO Susceptibility kits were used to test for resistance status using test papers: Lambdacyhalothrin 0.05%, Deltamethrin 0.05%, Permethrin 0.75%, DDT 4%, Propoxur 0.1% and Fenitrothion 1%. The quality of the test paper was checked against a laboratory susceptible An. gambiae Kisumu strain. Knockdown effect and mortality were measured in standard WHO susceptibility tests and cone bio-efficacy tests. Whereas, con bioassays on treated walls and ITNs were conducted using the laboratory susceptible An. gambiae Kisumu strain. The results from the surveillance recorded continued susceptibility of malaria vectors to commonly used insecticides. However, there were some isolated cases of resistance and/or reduced susceptibility to pyrethroid insecticides which may not compromise the current vector control interventions in the country. Anopheles gambiae s.l. showed resistance (15-28%) to each of the pyrethroids and to DDT but not to Organophosphates (Propoxur 0.1%), and Carbamates (Fenitrothion 1%). The information obtained from this surveillance is expected to be used to guide the National Malaria Control Programme on the rational selection of insecticides for malaria vector control and for the national mitigation plans for management and containment of malaria vector resistance in the country. The current observation warrants more vigilant monitoring of the susceptibility of malaria mosquitoes to commonly used insecticides in areas found with resistance and/or reduced levels of susceptibility of malaria vectors to insecticides, particularly in areas with heavy agricultural and/or public health use of insecticides where resistance is likely to develop. The current survey covered malaria vectors only and not the non malaria vectors (nuisance) mosquitoes such as Culex. Similar monitoring of insecticide susceptibility of this non malaria vectors may be needed to ensure public motivation for sustained use of ITNs/LLINs in the country. The surveillance leading to these results received funding from PMI/USAID through RTI International with Sub Agreement Number 33300212555.\u

    Mosquito net coverage in years between mass distributions: a case study of Tanzania, 2013.

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    BACKGROUND: The Government of Tanzania is the main source of long-lasting insecticidal nets (LLINs) for its population. Mosquito nets (treated and untreated) are also available in the commercial market. To sustain investments and health gains in the fight against malaria, it is important for the National Malaria Control Programme to monitor LLIN coverage especially in the years between mass distributions and to understand what households do if their free nets are deemed unusable. The aim of this paper was to assess standard LLIN indicators by wealth status in Tanzania in 2013, 2 years after the last mass campaign in 2011, and extend the analysis to untreated nets (UTNs) to investigate how households adapt when nets are not continuously distributed. METHODS: Between October-December 2013, a household survey was conducted in 3398 households in eight districts in Tanzania. Using the Roll Back Malaria indicators, the study analysed: (1) household net ownership; (2) access to nets; (3) population net use and (4) net use:access ratio. Outcomes were calculated for LLINs and UTNs. Results were analysed by socio-economic quintiles and by district. RESULTS: Only three of the eight districts had household LLIN ownership of more than 80%. In 2013, less than a quarter of the households had one LLIN for every two people and only half of the population had access to an LLIN. Only the wealthier quintiles increased their net ownership and access to levels above 80% through the addition of UTNs. Overall net use of the population was low (LLINs: 32.8%; UTNs: 9.5%) and net use:access ratio was below target level (LLINs: 0.66; UTN: 0.50). Both measures varied significantly by district. CONCLUSIONS: Two years after the last mass campaign, the percentage of households or population with access to LLINs was low. These findings indicate the average rate at which households in Tanzania lose their nets is higher than the rate at which they acquire new nets. The wealthiest households topped up their household net ownership with UTNs. Efforts to make LLINs available through commercial markets should be promoted, so those who can afford to buy nets purchase LLINs rather than UTNs. Net use was low around 40% and mostly explained by lack of access to nets. However, the use:access ratio was poor in Mbozi and Kahama districts warranting further investigations to understand other barriers to net use

    New methodological approaches to monitor long lasting insecticidal nets (LLINs) durability for sustained malaria control

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    Long lasting insecticidal nets (LLINs) are the current primary vector control measure to prevent malaria transmission. They function by inhibiting mosquitoes from blood feeding and also killing mosquitoes and hence provide personal and community protection respectively. With findings from different LLIN distribution programmes in different settings, it is assumed that the effective life of LLINs is 3 years. This is mostly due to wear and tear of the fabric and hence need for the introduction of the guidelines that provide standard methods to monitor the longevity of LLINs. The standard means established to monitor longevity of ITN is through cone bioassays, WHO tunnel tests and experimental hut evaluations. However, all the standard methods for assessing LLIN durability have limitations and the information collected on LLIN durability will only be useful if correctly collected using simple, realistic and reproducible methods. Thus to address this issue of high public health significance, we undertook two projects namely 1) ABCDR (Attrition, Bioefficacy, Chemical residual, Damage and Resistance) and 2) Holed Net project. The ABCDR project aimed at understanding of bednet durability in malaria endemic countries and factors affecting bednet durability with the main focus of using that information in improving the current methodologies by developing simple, realistic methods for assessing bednet efficacy while Holed Net project, aimed at understanding the association of size and location of net damage and interaction with insecticide concentration in order to ensure their continued efficacy and also work with manufacturers to optimize their longevity. The results showed that, Of 6067 campaign nets reported to have been received between 2009 and 2011, 35 % (2145 nets) were no longer present. In addition, most of those nets had been discarded (84 %) mainly because they were too torn (94 %) and only 39 % of distributed nets remain both present and in serviceable physical condition, a functional survival considerably below WHO assumptions of 50 % survival of a ‘three- year’ net. However, the majority of nets still retained substantial levels of permethrin and could still be bio-chemically useful against mosquitoes if their holes were repaired, adding evidence to the value of net care and repair campaigns. In conclusion, the findings from this study provided not only a deep insight into many aspects of LLIN durability but also evidence for revising the existing standard methods for LLIN durability. It also served as baseline information that was used to revise; i) the measurement of the standard entomological parameters i.e. mortality and blood feeding inhibition in order to develop a logistically simple, time saving and realistic method for assessing LLIN durability and ii) the measurement of proportional hole index (phi) in order to develop a “location adjusted phi”. Through findings from these studies, new bioassays have been developed to measure bednet durability with high throughput and robust data power. The developed bioassays are simple to use, very cost effective and reproducible for use in multiple countries

    "Siihen se tarina loppuu" Osallisuuden tukeminen saduttamalla

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    Opinnäytetyö oli toiminnallinen opinnäytetyö, jonka tavoitteena oli osallisuuden tukeminen sadutusmenetelmää hyödyntäen ja työn tarkoituksena oli myös tuottaa satukirja lasten kertomista saduista. Opinnäytetyö toteutettiin yhteistyössä päiväkoti Touhula Kangasalan kanssa kevään 2018 aikana. Työn tietoperusta koostui sadutuksesta, osallisuudesta, lasten kuulluksi tulemisesta, sekä varhaiskasvatuksesta. Opinnäytetyön toiminnallisessa osuudessa yksilösadutettiin lapsia ja näistä saduista koottiin työn liitteissä oleva satukirja. Lapset saivat kuvittaa omat satunsa ja kuvat liitettiin osaksi satukirjaa. Toiminnallinen osuus toteutettiin huhtikuussa 2018 ja sen aikana sadutettiin seitsemää 4-5-vuotiasta lasta. Työn tilaaja sai opinnäytetyön aikana syntyneen satukirjan jaettavaksi toiminnalliseen osuuteen osallistuneille lapsille. Lapset saivat antaa palautetta valmiista satukirjasta ja palaute heiltä oli positiivista. Lisäksi työ auttoi tukemaan lasten osallisuutta saduttamisen yhteydessä sekä opinnäytetyö toivottavasti innosti päiväkodin henkilökuntaa käyttämään sadutusmenetelmää myös tulevaisuudessa.This Bachelor’s thesis was practice-based and the aim was to support inclusion in the daycare centre Touhula in Kangasala by using the storycrafting method. Another goal was to make a storybook from the stories the children told. The thesis was implemented in spring 2018. The theoretical background consists of the storycrafting method, inclusion, what being heard is and early childhood education. In the practice part of the thesis, seven children aged four to five attended individual storycrafting sessiona. The children drew pictures to their stories and the stories were collected into a storybook. This practice part was carried out in April 2018. The Touhula Kangasala daycare centre received the finished storybook in May 2018. The children who took part into the storycrafting, also received copies of the storybook. The children also gave feedback about the book. The feedback was positive and the main aim of the thesis, to support the inclusion in the group, was achieved. The thesis also hopefully inspired the personnel to use the storycrafting method in the future

    Multiple insecticide resistance in Anopheles gambiae from Tanzania: a major concern for malaria vector control.

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    BACKGROUND: Malaria vector control in Tanzania is based on use of long-lasting insecticide treated nets (LLINs) and indoor residual spraying (IRS), which both rely on the use of chemical insecticides. The effectiveness of these control tools is endangered by the development of insecticide resistance in the major malaria vectors. This study was carried out to monitor the susceptibility status of major malaria vectors to insecticides used for IRS and LLINs in mainland Tanzania. METHODS: Mosquito larvae were collected in 20 sites of Tanzania mainland in 2015. Phenotypic resistance was determined using standard WHO susceptibility tests. Molecular assay were used to determine distribution of Anopheles gambiae sub-species. A microplate assay approach was used for identifying enzyme levels on single mosquitoes from each sites compared with a susceptible reference strain, An. gambiae sensu stricto (s.s.) Kisumu strain. RESULTS: Anopheles arabiensis was the dominant malaria specie in the country, accounting for 52% of the sibling species identified, while An. gambiae s.s. represented 48%. In Arumeru site, the dominant species was An. arabiensis, which was resistant to both pyrethroids (permethrin and deltamethrin), and pirimiphos-methyl, and had significant elevated levels of GSTs, non-specific esterases, and oxidase enzymes. An. arabiensis was also a dominant species in Kilombero and Kondoa sites, both were resistant to permethrin and deltamethrin with significant activity levels of oxidase enzymes. Resistance to bendiocarb was recorded in Ngara site where specie composition is evenly distributed between An. gambiae s.s. and An.arabiensis. Also bendiocarb resistance was recorded in Mbozi site, where An. gambiae s.s. is the dominant species. CONCLUSIONS: Overall, this study confirmed resistance to all four insecticide classes in An. gambiae sensu lato in selected locations in Tanzania. Results are discussed in relation to resistance mechanisms and the optimization of resistance management strategies

    Advantages and Limitations of Commercially Available Electrocuting Grids for Studying Mosquito Behaviour.

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    Mosquito feeding behaviour plays a major role in determining malaria transmission intensity and the impact of specific prevention measures. Human Landing Catch (HLC) is currently the only method that can directly and consistently measure the biting rates of anthropophagic mosquitoes, both indoors and outdoors. However, this method exposes the participant to mosquito-borne pathogens, therefore new exposure-free methods are needed to replace it. Commercially available electrocuting grids (EGs) were evaluated as an alternative to HLC using a Latin Square experimental design in Dar es Salaam, Tanzania. Both HLC and EGs were used to estimate the proportion of human exposure to mosquitoes occurring indoors (πi), as well as its two underlying parameters: the proportion of mosquitoes caught indoors (Pi) and the proportion of mosquitoes caught between the first and last hour when most people are indoors (Pfl). HLC and EGs methods accounted for 69% and 31% of the total number of female mosquitoes caught respectively and both methods caught more mosquitoes outdoors than indoors. Results from the gold standard HLC suggest that An. gambiae s.s. in Dar es Salaam is neither exophagic nor endophagic (Pi ≈ 0.5), whereas An. arabiensis is exophagic (Pi < < 0.5). Both species prefer to feed after 10 pm when most people are indoors (Pfl > >0.5). EGs yielded estimates of Pi for An. gambiae s.s., An. arabiensis and An. coustani, that were approximately equivalent to those with HLC but significantly underestimated Pfl for An. gambiae s.s. and An. coustani. The relative sampling sensitivity of EGs declined over the course of the night (p ≤ 0.001) for all mosquito taxa except An. arabiensis. Commercial EGs sample human-seeking mosquitoes with high sensitivity both indoors and outdoors and accurately measure the propensity of Anopheles malaria vectors to bite indoors rather than outdoors. However, further modifications are needed to stabilize sampling sensitivity over a full nocturnal cycle so that they can be used to survey patterns of human exposure to mosquitoes

    Comparative performance of three experimental hut designs for measuring malaria vector responses to insecticides in Tanzania.

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    BACKGROUND: Experimental huts are simplified, standardized representations of human habitations that provide model systems to evaluate insecticides used in indoor residual spray (IRS) and long-lasting insecticidal nets (LLINs) to kill disease vectors. Hut volume, construction materials and size of entry points impact mosquito entry and exposure to insecticides. The performance of three standard experimental hut designs was compared to evaluate insecticide used in LLINs. METHODS: Field studies were conducted at the World Health Organization Pesticide Evaluation Scheme (WHOPES) testing site in Muheza, Tanzania. Three East African huts, three West African huts, and three Ifakara huts were compared using Olyset(®) and Permanet 2.0(®) versus untreated nets as a control. Outcomes measured were mortality, induced exophily (exit rate), blood feeding inhibition and deterrence (entry rate). Data were analysed using linear mixed effect regression and Bland-Altman comparison of paired differences. RESULTS: A total of 613 mosquitoes were collected in 36 nights, of which 13.5% were Anopheles gambiae sensu lato, 21% Anopheles funestus sensu stricto, 38% Mansonia species and 28% Culex species. Ifakara huts caught three times more mosquitoes than the East African and West African huts, while the West African huts caught significantly fewer mosquitoes than the other hut types. Mosquito densities were low, very little mosquito exit was measured in any of the huts with no measurable exophily caused by the use of either Olyset or Permanet. When the huts were directly compared, the West African huts measured greater exophily than other huts. As unholed nets were used in the experiments and few mosquitoes were captured, it was not possible to measure difference in feeding success either between treatments or hut types. In each of the hut types there was increased mortality when Permanet or Olyset were present inside the huts compared to the control, however this did not vary between the hut types. CONCLUSIONS: Both East African and Ifakara huts performed in a similar way although Ifakara huts allowed more mosquitoes to enter, increasing data power. The work convincingly demonstrates that the East African huts and Ifakara huts collect substantially more mosquitoes than the West African huts

    Methods of Correlation Digital Photonics in the Diagnosis of Complex Medical Conditions

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    In this paper we analyze the possibility of using special methods and equipment for coherent photonics during working with multiparameter information. Reverse paraphase coding and operational analysis of multiparameter data allow the implementation of various correlation algorithms for photonic medical diagnostic systems - search of precedent, compliance diagnosis, deterministic diagnostics, Bayes and metric algorithms. The results of experimental studies of medical diagnostics and prediction of complex situations are presented. Such analysis is carried out with the help of vector-matrix multiplication by the methods of laser photonics. It is significant that with the extension of the range of probability algorithms, it is possible to preserve the main advantages of the holographic method: multidimensionality, high speed, efficiency and reliability. Photonics methods in diagnostics have particular importance in connection with the development of the first sample of a photonic processor. Keywords: laser photonics, correlation, coherence, optical computing, photonic processo

    Effects of engaging in success for all on children's causal attributions

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    At-risk children in danger of experiencing failure in reading, face negative life consequences that may be alleviated by the inclusion of an attributional training program that would increase the possibilities of success. The present study investigated the causal attributions of students in a Success for All (SFA) school versus a traditional reading curriculum. A total of 197 children, 89 from the SFA experimental school, and 108 control children participated in this study. Data were collected through the posttest administration of the Causal Beliefs About Reading Questionnaire based on the attribution work by Ames (1978, 1981, 1984) and others. Pretest reading achievement (Woodcock, Durrell) and diagnostic measures (PPVT) from the broader study by Chambers et al. (1996) were used as covariates, since pretest causal data were not available. The correlations indicated some interesting patterns. Of significance, were the negative correlations between ability and task difficulty, and the positive correlations between ability and effort. While the ANCOVA results for the hypotheses were not significant, further ANOVA results employing ratings of children's perceptions of success in reading were significant. In particular, there was a 2-way interaction effect for the type of reading program and perceptions of success in reading on attributions to the difficulty of the task. These findings suggest important motivational and feedback techniques that should be taken into consideration by classroom teachers. The key is for teachers to use research-based teaching techniques in combination with effective attributional practices

    Enantiopure Ferrocene-Based Planar-Chiral Iridacycles:Stereospecific Control of Iridium-Centred Chirality

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    Reaction of [IrCp*Cl-2](2) with ferrocenylimines (Fc=NAr, Ar=Ph, p-MeOC6H4) results in ferrocene C-H activation and the diastereoselective synthesis of half-sandwich iridacycles of relative configuration S-p*,R-Ir*. Extension to (S)-2-ferrocenyl-4-(1-methylethyl)oxazoline gave highly diastereoselective control over the new elements of planar chirality and metal-based pseudo-tetrahedral chirality, to give both neutral and cationic half-sandwich iridacycles of absolute configuration S-c,S-p,R-Ir. Substitution reactions proceed with retention of configuration, with the planar chirality controlling the metal-centred chirality through an iron-iridium interaction in the coordinatively unsaturated cationic intermediate
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