Developing, testing and implementing novel molecular diagnostic tests and procedures for malaria at the individual and population level in East and West Africa

Malaria is a global public health issue responsible for an estimated 219 million cases and 435’000 deaths in 2017. Although malaria control interventions have led to a significant decrease in mortality over the past decade, no further progress in reducing global malaria burden was achieved since 2016. Novel malaria control approaches, such as highly effective vaccines and improved diagnostic tools are needed to prevent a resurgence of malaria as has been seen in the 1970s. The overall goal of this PhD thesis is to contribute to the development, validation and implementation of novel molecular diagnostic tools in malaria endemic countries targeting all human infective malaria species. This thesis was conducted within the framework of six clinical trials evaluating the PfSPZ Vaccine, an experimental malaria vaccine based on the immunization with radiation-attenuated whole, purified, cryopreserved, metabolically active sporozoites in Tanzania and Equatorial Guinea. We used controlled human malaria infection (CHMI) to assess vaccine efficacy in these cohorts. Compared to large field studies, CHMI studies allow to test various vaccine regimen and dosing in smaller, well defined cohorts in a short time period. In part one, we aimed to closely monitor malaria parasites at the individual level by establishing a robust laboratory qPCR-platform for molecular monitoring of asexual blood stage parasitaemia. This platform was used to evaluate the efficacy of PfSPZ Vaccine by homologous CHMI in Tanzanian and Equatorial Guinean adults. Part one was structured around four manuscripts: Manuscript 1-3: Safety, immunogenicity and efficacy of attenuated whole sporozoite vaccines in Tanzanian and Equatorial Guinean volunteers. In clinical trials conducted in malaria pre-exposed volunteers from Tanzania and Equatorial Guinea, the PfSPZ Vaccine was found to be well tolerated and safe, even in high-risk populations such as infants and HIV+ volunteers. The use of CHMI in malaria pre-exposed adults has been proven to be highly effective. These trials revealed that the degree of immune response and high level of protection seen in previous studies in malaria-naïve volunteers, was not reproducible to the same level in Tanzanian and Equato-Guinean populations. Manuscript 4: Controlled Human Malaria Infections in Tanzania and Equatorial Guinea: The impact of malaria pre-exposure on diagnosis and multiplication rate of P. falciparum parasites We used the parasite multiplication rate (PMR), the fold change in number of parasites in peripheral blood over one life cycle, to characterize the impact of malaria pre-exposure on the outcome of CHMI. Compared to malaria-naïve German volunteers, the parasite’s ability to replicate was significantly reduced in Tanzanian and Equato-Guinean volunteers when challenged with the identical dose, strain and route of cryopreserved, purified P. falciparum sporozoites. We used two different approaches to demonstrate the impact of malaria preexposure on the multiplication rate of P. falciparum parasites. First, we showed that recently drug-cleared parasitaemia from an ongoing P. falciparum field infection or P. falciparum and P. malariae co-infection leads to a significantly reduced PMR. Second, PMR is significantly reduced after two consecutive homologous CHMI conducted in the same volunteer at 7 months interval. This data indicates the rapid acquisition or recall of parasite growth reducing immune effector mechanisms limiting the growth of asexual blood stages in vivo. In part two, we aimed to adapt and extend molecular diagnostic tools for improvement of malaria surveillance at the population level by developing novel high-throughput, fielddeployable and highly sensitive tools and approaches. Part two was structured around five manuscripts: Manuscript 5: A multiplex qPCR approach for detection of pfhrp2 and pfhrp3 gene deletions in multiple strain infections of Plasmodium falciparum In response to the emerging threat of P. falciparum strains lacking pfhrp2 and/or pfhrp3 genes and therefore evading detection by PfHRP2-based RDTs, we developed a qPCR-based assay well suited for high-throughput identification of pfhrp2 and pfhrp3 gene deletions in P. falciparum isolates. The ability to detect “masked” pfhrp2/3 deletions is probably the most interesting feature of our approach, because it will allow to study the epidemiology of pfhrp2/3 deletions in malaria endemic regions where a high proportion of the population carries multiple strain P. falciparum co-infections. Manuscript 6: High Throughput Extraction and Analysis of Nucleic Acids from Rapid Diagnostic Tests for Molecular Surveillance of Malaria This manuscript describes our attempt to improve extraction of nucleic acids from used malaria RDTs. We used an approach which enabled us to extract total nucleic acids, including DNA and RNA from these RDT strips. This approach increased the overall sensitivity for the detection of Plasmodium spp. parasites in the small volume of blood which is available on an RDT stored at room temperature. We used samples collected during CHMI as a platform to evaluate and compare the ability of our protocol to detect and quantify P. falciparum parasites with microscopy and qPCR. Manuscript 7: ELIMU-MDx: A Web-Based, Open-Source Platform for Storage, Management and Analysis of Diagnostic qPCR Data We developed a web-based and open-source software for storage, management and analysis of diagnostic qPCR data. In response to the vast amount of qPCR data generated during a series of CHMIs and other epidemiological studies conducted in Tanzania and Equatorial Guinea, we decided to design and build this platform which facilities the larger scale analysis and interpretation of diagnostic qPCR data. Manuscript 8: Molecular monitoring of the diversity of human pathogenic malaria species in blood donations on Bioko Island, Equatorial Guinea In collaboration with the central blood bank in Malabo, Equatorial Guinea we analysed 200 blood donations for the presence of Plasmodium spp. parasites by a novel, multiplex qPCR monitoring all human infective malaria species in a single reaction. We found that more than one quarter of the blood donations contained malaria parasites and that 75% of P. falciparum and 100% of P. malariae and P. ovale spp. infections were missed by routinely performed RDT and microscopy. Manuscript 9: Two cases of long-lasting, sub-microscopic Plasmodium malariae infections in adults from Coastal Tanzania In this report we describe two cases of P. malariae infections that were identified during a study evaluating the safety, tolerability and efficacy of the PfSPZ Vaccine in Bagamoyo, Tanzania. Since these two adult participants were enrolled into a clinical trial, we were provided with a unique opportunity to study clinical manifestations of P. malariae over a follow up period of four months

Designing Technologies to Support Professional and Workplace Learning for Situated Practice

The papers in this special section focus on designing technologies to support professional and workplace learning in situated practices. In an era of global, organizational, and technological change, all of which are transforming the world of work, professional and workplace learning are critical for employability and organizational competitiveness. A range of fundamental transformations is changing how people work. Digital technologies are replacing human labor and, at the same time, are accelerating the expansion of job roles and work practices. Work is becoming increasingly specialized, which means that professionals in collaborative and networked ways across discipline and organization boundaries. In parallel, labor is increasingly decentralized, making decisionmaking more distributed and raising the need for remote communication and collaboration. Subsequently, work is becoming more independent from time and place, as people connect, collaborate, and work via digital technologies. These changes come with a need for substantial and continuous workplace learning, and with the need for changes in how workplace learning happens. Of course, digital technologies are already used to provide learning and training in workplaces. However, most of these learning technologies have been developed for formal education (e.g., K- 12 and higher education) rather than in workplace contexts. There is a need to understand and evidence workplace learning needs and to further develop technologies that can support and scale workplace learning

Collapse of Coherent Large Scale Flow in Strongly Turbulent Liquid Metal Convection

The large-scale flow structure and the turbulent transfer of heat and momentum are directly measured in highly turbulent liquid metal convection experiments for Rayleigh numbers varied between $4 \times 10^5$ and $\leq 5 \times 10^9$ and Prandtl numbers of $0.025~\leq~Pr~\leq ~0.033$. Our measurements are performed in two cylindrical samples of aspect ratios $\Gamma =$ diameter/height $= 0.5$ and 1 filled with the eutectic alloy GaInSn. The reconstruction of the three-dimensional flow pattern by 17 ultrasound Doppler velocimetry sensors detecting the velocity profiles along their beamlines in different planes reveals a clear breakdown of coherence of the large-scale circulation for $\Gamma = 0.5$. As a consequence, the scaling laws for heat and momentum transfer inherit a dependence on the aspect ratio. We show that this breakdown of coherence is accompanied with a reduction of the Reynolds number $Re$. The scaling exponent $\beta$ of the power law $Nu\propto Ra^{\beta}$ crosses \FIN{eventually} over from $\beta=0.221$ to 0.124 when the liquid metal flow at $\Gamma=0.5$ reaches $Ra\gtrsim 2\times 10^8$ and the coherent large-scale flow is completely collapsed.Comment: 4 pages, 5 figures, 1 supplementary with 1 figure and 4 tables, 1 movi

Visuelle Medien und die (Wieder-)Herstellung von Unmittelbarkeit

Die Verfasser argumentieren, dass bei aller berechtigten Skepsis gegenüber visuellen Medien die ethnografische Forschung pragmatisch auf sie zurückgreifen muss. Als empirisch fundierte Forschung lässt sie sich von der Teilnahme an sozialen Praktiken leiten und irritieren und ist dafür auf Importe aus den untersuchten Feldern und ihren Praktiken angewiesen. An zwei Fallbeispielen aus der soziologischen Praxisforschung wird gezeigt, dass der Einsatz von visuellen Medien als Vermittlern konzeptuell und vor allem praktisch voraussetzungsvoll ist. Der Einsatz von visuellen Medien setzt die Anreicherung des generierten Datenmaterials mit in der Praxis erworbenem bzw. erfahrenem Kontext- und Wahrnehmungswissen durch den Ethnografen voraus, damit dieses als Dokument in der wissenschaftlichen Praxis funktioniert. Die Art zu sehen, die der Forscher im Feld gelernt hat, muss er dem Betrachter seiner Bilder vermitteln. Erst so kann Unmittelbarkeit zwischen der Forschergruppe und dem Bildmaterial entstehen - und es kann Teil der ethnografischen Praxis werden. (entnommen aus Sowiport.de