Malaria rapid diagnostic tests in elimination settings—can they find the last parasite?

AbstractRapid diagnostic tests (RDTs) for malaria have improved the availability of parasite-based diagnosis throughout the malaria-endemic world. Accurate malaria diagnosis is essential for malaria case management, surveillance, and elimination. RDTs are inexpensive, simple to perform, and provide results in 15–20 min. Despite high sensitivity and specificity for Plasmodium falciparum infections, RDTs have several limitations that may reduce their utility in low-transmission settings: they do not reliably detect low-density parasitaemia (≤200 parasites/µL), many are less sensitive for Plasmodium vivax infections, and their ability to detect Plasmodium ovale and Plasmodium malariae is unknown. Therefore, in elimination settings, alternative tools with higher sensitivity for low-density infections (e.g. nucleic acid-based tests) are required to complement field diagnostics, and new highly sensitive and specific field-appropriate tests must be developed to ensure accurate diagnosis of symptomatic and asymptomatic carriers. As malaria transmission declines, the proportion of low-density infections among symptomatic and asymptomatic persons is likely to increase, which may limit the utility of RDTs. Monitoring malaria in elimination settings will probably depend on the use of more than one diagnostic tool in clinical-care and surveillance activities, and the combination of tools utilized will need to be informed by regular monitoring of test performance through effective quality assurance

Evaluating Entrepreneurial Features of Firm's Growth Using Confirmatory Factor Analysis

The growth of Small and medium-size firms cannot ensue without the entrepreneurial features and the environment that the firm operates. The entrepreneurial characteristics, therefore, are vital due to the unique individualism of firm owners or sponsors. Construction SME growth-oriented firms are a significant contributor to Ghana's economic gain. Conversely, the concept of growth varies from one entrepreneur to the others depending on the exhibited skills by the entrepreneurs, hence entrepreneurial features. Numerous factors influence the entrepreneurial features as a factor of firm’s growth. Some are of the factors are established and categorised as having strong influence while others are classified weak. This study, therefore, adopted the confirmatory factor analytical technique to justify the factors after exploring. To achieve the goal of the study, respondents such as firm owners, SME managers and construction professionals engaged by SMEs as the population were administered with questionnaires. In all, 315 questionnaires were given out in the form of semi-structured structured, but only 228 were retrieved for analysis representing a responds rate of 72 percent. The study established Cronbach alpha and composite reliability values that predicted the entrepreneurial feature as a subsequent determinant of firm’s growth. Additionally, the hypothesis was supported statistically suggesting that there is a direct relationship between entrepreneurial features and firm growth

The Impact of Innovation of the Construction Industry in Ghana

The essence of this paper therefore, is to bring out the impact of innovation of the Construction industry in Ghana and also to establish tangible and intangible benefits associated with innovation.  Analysis of the relevant literature indicates the impact and the problem of slow adaptation of innovation and new ways of working within the construction industry is a great concern to most organization that operates within and outside the industry. To bridge this conservatism attitude of innovation in the industry, it is fundamental to explore the impact and for that matter the benefits of innovation within the industry. This paper however, seeks to embark on this investigation on the impact of innovation and to bring to light its related benefits and how these would be achieved. Data were collected among construction professionals (Consultants) and Contractors via questionnaires supported by informal interviews. Analysis of the data was done using simple percentage method and the findings were represented in the form of pie-chart and bar-chart using micro-soft excel programme. The study established that innovation within an industry brings about increased in economic growth and profitability. The study also revealed that ease of working at a lower cost with much precision is assured when there is innovation Recommendation of effective coordination between Consultants and Contractors must exist to facilitate innovation beginning from research and development set-up within the firms. Keywords: Impact; innovation; Construction; industry; Ghan

Geochemical Characteristics of Granitoids (Ho Gneiss) from the Pan – African Dahomeyide Belt, Southeastern, Ghana: Implications for Petrogenesis and Tectonic Setting

The Pan-African Dahomeyide belt exposed in Southeastern, Ghana, consist of granitoid gneisses locally known as Ho gneiss. These rocks are thought to be part of the West African Craton (WAC) which was reworked during the Pan-African Orogeny, and may be time equivalent with the Kara gneisses. Petrographical and whole rock geochemical analyses have been used to evaluate the characteristics, petrogenesis and mode of emplacement of the granitoids. The new data reasonably suggest that the Ho gneiss consist mainly of biotite augen gneisses of both mafic and felsic rock suites. Geochemically, these rocks show tonalitic to quartz monzonite but mainly granodiorites affinities. They are metaluminous to weakly peraluminous, I-type, magnesian to ferroan and calcic to alkali calcic. With these varying features, the granitoids mimic mantle derived magma source which mixed or mingled with crustally derived melt. The rocks display varying REEs and trace elements patterns but, their LREEs and LILE enrichment with  the noticeable enrichment in Rb, Ba, K and especially Pb and negative Ti, Ta, Nb observed among majority of the samples are typical signature of ‘‘arc rocks’’ or continental crustal materials. Their incompatible trace element ratios, such as Th/U (1.07 – 13.87), K/Rb (272 – 574.47), Th/Yb (0.79 – 15.09), Ta/Yb (0.25 -0.64 ), Ce/Pb (mainly 1.62 – 7.88 ) and high Ba/Nb (19.55 – 314.17, with TA = 1565.00), are similar to those of the continental crust. The rocks are characterised by subduction related Sr/Y content (< 100), except sample MA8 that shows high concentration of Sr/Y (227.71). The magnesian affinity reflects relatively hydrous, oxidizing source which is consistent with origins that are broadly subduction related. Their high – K nature also points to an important petrogenetic role of remelting and differentiation of arc – accretionary complex crust. These geochemical signatures are likely to be related to metasomatism of the sub – continental lithospheric mantle via crustal recycling. In conclusion, the granitoids may have from melting of igneous source in a subduction related environment. Keywords: Pan-African belt, Dahomeyide, Southeastern Ghana, Ho gneisses, Geochemistry, petrogenesi

Analysis of seed yam varieties, sources and quantity demanded by farmers in major yam producing districts in Ghana

The study analysed the varieties, sources and quantities of seed yam demanded by farmers for cultivation in order to inform policies aimed at ensuring adequate supply of quality seed yam of desirable varieties at an affordable price to boost yam productivity for improved income and livelihoods. A structured questionnaire was administered to 380 randomly selected yam farmers in three major yam producing districts in Ghana in 2015. The data analysis was done using STATA statistical software. The study identified Pona/Punjo, Lariboko, Asana, Afebetuye, Dente, Olondo and Kparinjo as the yam varieties mainly cultivated by farmers in a reducing order with high market demands by consumers. Own production remains the major source of seed yam for farmers. The estimated monetary value of quantity of seed yam used by farmers for cultivation in 2014 farming season was GH¢ 198, 552,841.0 (USD 51,706,469.0) in the study locations. About GH¢ 5,679,979.0 (USD 1,479,161.2) worth of quantities of seed yam was obtained from the market and other sources. The results demonstrate the existence of market potential for commercial seed yam production and supply in Ghana. Commercial seed yam certification system and yam breeding activities should target the identified yam varieties

Willingness to pay for biofertilizers among grain legume farmers in northern Ghana

Open Access Journal; Published online: 27 April 2018Background: The call for use of improved Soil Fertility Management (SFM) technologies is a prerequisite to increase agricultural productivity among farmers. This study assessed farmers’ willingness to pay (WTP) for selected financially rewarding biofertilizer technologies/packages for legume production in northern Ghana. Primary data was elicited from 400 grain legume farmers selected from Northern and Upper West Regions of Ghana through a simple random sampling technique. The double bounded dichotomous choice (DBDC) format of contingent valuation approach was employed to elicit willingness to pay values and determinants of farmers WTP was evaluated using the maximum likelihood estimation procedure. Results: The results showed that about 60%, 25% and 46% of soya, cowpea and groundnuts farmers were willing to pay for the selected biofertilizers (Biofix, BR3267 and Legumefix respectively) at prices not exceeding GHC 14.00, GHC 28.00 and GHC 20.00 per 0.2kg of the respective biofertilizers. Legume farmers in Northern Region were however willing to pay higher for the three biofertilizer technologies as compared to their counterparts in Upper West Region. For 0.2 kg each of Biofix, BR3267 and Legumefix, farmers in Northern Region were willing to pay approximately GHC 17.00, GHC 12.00 and GHC 23.00 respectively whereas those in Upper West Region were willing to pay GHC 14.00, GHC 9.00 and GHC 11.00 for the same quantity of each biofertilizer. The study identified farming experience, FBO membership, awareness and previous use of biofertilizers as significant determinants of farmers’ willingness to pay for Biofertilizers. Conclusion: Comparatively, mean prices farmers are willing to pay for these three technologies are below ex-factory prices, hence subsidizing the cost of production of these biofertilizers in the initial stages would be relevant for improving farmers’ uptake of these fertilizers. Sustained awareness creation through periodic education and sensitization by using FBOs as leverage points is also highly recommended to improve farmers’ understanding of the concept of biofertilizer use

Characterization of immunoglobulin G antibodies to Plasmodium falciparum sporozoite surface antigen MB2 in malaria exposed individuals

<p>Abstract</p> <p>Background</p> <p>MB2 protein is a sporozoite surface antigen on the human malaria parasite <it>Plasmodium falciparum</it>. MB2 was identified by screening a <it>P. falciparum </it>sporozoite cDNA expression library using immune sera from a protected donor immunized via the bites of <it>P. falciparum</it>-infected irradiated mosquitoes. It is not known whether natural exposure to <it>P. falciparum </it>also induces the anti-MB2 response and if this response differs from that in protected individuals immunized via the bites of <it>P. falciparum </it>infected irradiated mosquitoes. The anti-MB2 antibody response may be part of a robust protective response against the sporozoite.</p> <p>Methods</p> <p>Fragments of polypeptide regions of MB2 were constructed as recombinant fusions sandwiched between glutathione S-transferase and a hexa histidine tag for bacterial expression. The hexa histidine tag affinity purified proteins were used to immunize rabbits and the polyclonal sera evaluated in an <it>in vitro </it>inhibition of sporozoite invasion assay. The proteins were also used in immunoblots with sera from a limited number of donors immunized via the bites of <it>P. falciparum </it>infected irradiated mosquitoes and plasma and serum obtained from naturally exposed individuals in Kenya.</p> <p>Results</p> <p>Rabbit polyclonal antibodies targeting the non-repeat region of the basic domain of MB2 inhibited sporozoites entry into HepG2-A16 cells <it>in vitro</it>. Analysis of serum from five human volunteers that were immunized via the bites of <it>P. falciparum </it>infected irradiated mosquitoes that developed immunity and were completely protected against subsequent challenge with non-irradiated parasite also had detectable levels of antibody against MB2 basic domain. In contrast, in three volunteers not protected, anti-MB2 antibodies were below the level of detection. Sera from protected volunteers preferentially recognized a non-repeat region of the basic domain of MB2, whereas plasma from naturally-infected individuals also had antibodies that recognize regions of MB2 that contain a repeat motif in immunoblots. Sequence analysis of eleven field isolates and four laboratory strains showed that these antigenic regions of the basic domain of the <it>MB2 </it>gene are highly conserved in parasites obtained from different parts of the world. Moreover, anti-MB2 antibodies also were detected in the plasma of 83% of the individuals living in a malaria endemic area of Kenya (n = 41).</p> <p>Conclusion</p> <p>A preliminary analysis of the human humoral response against MB2 indicates that it may be an additional highly conserved target for immune intervention at the pre-erythrocytic stage of <it>P. falciparum </it>life cycle.</p

Repellency Potential, Chemical Constituents of Ocimum Plant Essential Oils, and Their Headspace Volatiles against Anopheles gambiae s. s., Malaria Vector

African malaria mosquitoes (Anopheles gambiae sensu stricto) transmit a malaria parasite (Plasmodium falciparum) to humans. The current control strategies for the vector have mainly focussed on synthetic products, which negatively impact the environment and human health. Given the potential use of environmentally friendly plant-derived volatiles as a control, this work aims to examine and compare the repellency potential of essential oils and headspace volatiles from Ocimum gratissimum, Ocimum tenuiflorum, and Ocimum basilicum and their chemical compositions. The repellency potential and chemical composition of the plants were achieved by using the protected arm-in-cage method and gas chromatography-mass spectrometry (GC-MS) analysis. Among the three Ocimum species, both the essential oils and the headspace volatiles from O. tenuiflorum achieved the longest repellency time lengths of 90–120 minutes. One hundred and one (101) chemical constituents were identified in the headspace volatiles of the three Ocimum spp. Nonetheless, (−)-camphor, (E)-γ-bisabolene, terpinolene, β-chamigrene, cubedol, (E)-farnesol, germacrene D-4-ol, viridiflorol, γ-eudesmol, tetracyclo [6.3.2.0 (2,5).0(1,8)] tridecan-9-ol, 4,4-dimethyl, α-eudesmol, isolongifolol, and endo-borneol were unique only to O. tenuiflorum headspace volatiles. Either essential oils or headspace volatiles from O. tenuiflorum could offer longer protection time length to humans against An. gambiae. Though field studies are needed to assess the complementarity between the chemical constituents in the headspace volatiles of O. tenuiflorum, our observations provide a foundation for developing effective repellents against An. gambiae

Isolation of human intrahepatic leukocytes for phenotypic and functional characterization by flow cytometry

With the growing appreciation of tissue-resident immunity, studying tissue-specific immune cells contributing to both homeostasis and disease is imperative. Here, we provide a protocol for the isolation of human intrahepatic leukocytes (IHL) maximizing viability, purity, and yield. Our protocol is scalable by tissue weight, allowing for reproducible and efficient IHL liberation suitable for functional characterization, cell isolation, and profiling by flow (or mass) cytometry. Furthermore, we provide a "guide" to determine an expected IHL yield per gram of tissue processed. For complete details on the use and execution of this protocol, please refer to Stegmann et al. (2016), Pallett et al. (2017), Easom et al. (2018), Swadling et al. (2020), Pallett et al. (2020), and Zakeri et al. (2022)