Quantum oscillations in the parent pnictide BaFe2_2As2_2 : itinerant electrons in the reconstructed state

We report quantum oscillation measurements that enable the direct observation of the Fermi surface of the low temperature ground state of \ba122. From these measurements we characterize the low energy excitations, revealing that the Fermi surface is reconstructed in the antiferromagnetic state, but leaving itinerant electrons in its wake. The present measurements are consistent with a conventional band folding picture of the antiferromagnetic ground state, placing important limits on the topology and size of the Fermi surface.Comment: 5 pages, 3 figure

Transplacental transmission: A rare case of Ebola virus transmission

During the mid-transmission period of the Ebola virus disease (EVD) outbreak in Sierra Leone, a 19-year-old pregnant woman, who was a petty trader in a health facility in Freetown, noticing no fetal movement for the past 3 days, reported to a health facility. Medical history and laboratory testing showed no abnormalities except that she was positive for sickle cell. She was not known to any surveillance team of having any epidemiological link to EVD case. She was induced with oral medications as well as IV infusion. EVD test showed that the fetus was positive to EVD with a high threshold value of 21, while the woman was negative for EVD with a threshold value of 42. The woman was positive to EVD IgG but negative to EVD IgM by ELISA technique. This is a rare EVD case in the period of medium transmission. We conclude that the woman may have come into contact with a low dose of virus not enough to cause a full blown EVD and that her immune system was able to stop the virus from further replication

Isolation of Angola-like Marburg virus from Egyptian rousette bats from West Africa.

Marburg virus (MARV) causes sporadic outbreaks of severe Marburg virus disease (MVD). Most MVD outbreaks originated in East Africa and field studies in East Africa, South Africa, Zambia, and Gabon identified the Egyptian rousette bat (ERB; Rousettus aegyptiacus) as a natural reservoir. However, the largest recorded MVD outbreak with the highest case-fatality ratio happened in 2005 in Angola, where direct spillover from bats was not  shown. Here, collaborative studies by the Centers for Disease Control and Prevention, Njala University, University of California, Davis USAID-PREDICT, and the University of Makeni identify MARV circulating in ERBs in Sierra Leone. PCR, antibody and virus isolation data from 1755 bats of 42 species shows active MARV infection in approximately 2.5% of ERBs. Phylogenetic analysis identifies MARVs that are similar to the Angola strain. These results provide evidence of MARV circulation in West Africa and demonstrate the value of pathogen surveillance to identify previously undetected threats

Enabling methods for community health mapping in developing countries

<p>Abstract</p> <p>Background</p> <p>Spatial epidemiology is useful but difficult to apply in developing countries due to the low availability of digitized maps and address systems, accurate population distributions, and computational tools. A community-based mapping approach was used to demonstrate that participatory geographic information system (PGIS) techniques can provide information helpful for health and community development.</p> <p>Results</p> <p>The PGIS process allowed for the rapid determination of sectional (neighborhood) boundaries within the city of Bo, Sierra Leone. When combined with data about hospital laboratory visits, a catchment area for one hospital in Bo could be established. A survey of households from within the catchment area determined that the average population per household (about 6 individuals) was similar to that found in the 2004 census. However, we also found that the average house was inhabited by more than one household, for an average of 17.5 inhabitants per residential building, which is critical information to know when estimating population size using remote imagery that can detect and enumerate buildings.</p> <p>Conclusions</p> <p>The methods developed in this paper serve as a model for the involvement of communities in the generation of municipal maps and their application to community and health concerns.</p

Angle-dependence of quantum oscillations in YBa2Cu3O6.59 shows free spin behaviour of quasiparticles

Measurements of quantum oscillations in the cuprate superconductors afford a new opportunity to assess the extent to which the electronic properties of these materials yield to a description rooted in Fermi liquid theory. However, such an analysis is hampered by the small number of oscillatory periods observed. Here we employ a genetic algorithm to globally model the field, angular, and temperature dependence of the quantum oscillations observed in the resistivity of YBa2Cu3O6.59. This approach successfully fits an entire data set to a Fermi surface comprised of two small, quasi-2-dimensional cylinders. A key feature of the data is the first identification of the effect of Zeeman splitting, which separates spin-up and spin-down contributions, indicating that the quasiparticles in the cuprates behave as nearly free spins, constraining the source of the Fermi surface reconstruction to something other than a conventional spin density wave with moments parallel to the CuO2 planes.Comment: 8 pages, 4 figure

Capacity building permitting comprehensive monitoring of a severe case of Lassa hemorrhagic fever in Sierra Leone with a positive outcome: Case Report

Lassa fever is a neglected tropical disease with a significant impact on the health care system of endemic West African nations. To date, case reports of Lassa fever have focused on laboratory characterisation of serological, biochemical and molecular aspects of the disease imported by infected individuals from Western Africa to the United States, Canada, Europe, Japan and Israel. Our report presents the first comprehensive real time diagnosis and characterization of a severe, hemorrhagic Lassa fever case in a Sierra Leonean individual admitted to the Kenema Government Hospital Lassa Fever Ward. Fever, malaise, unresponsiveness to anti-malarial and antibiotic drugs, followed by worsening symptoms and onset of haemorrhaging prompted medical officials to suspect Lassa fever. A recombinant Lassa virus protein based diagnostic was employed in diagnosing Lassa fever upon admission. This patient experienced a severe case of Lassa hemorrhagic fever with dysregulation of overall homeostasis, significant liver and renal system involvement, the interplay of pro- and anti-inflammatory cytokines during the course of hospitalization and an eventual successful outcome. These studies provide new insights into the pathophysiology and management of this viral illness and outline the improved infrastructure, research and real-time diagnostic capabilities within LASV endemic areas

Human preparedness: Relational infrastructures and medical countermeasures in Sierra Leone

This paper examines health worker experiences in two areas of post-epidemic preparedness in Sierra Leone - vaccine trials and laboratory strengthening - to reflect on the place of people in current models of epidemic response. Drawing on ethnographic research and interviews with health workers in the aftermath of Ebola, it explores the hopes and expectations that interventions foster for frontline workers in under-resourced health systems, and describes the unseen work involved in sustaining robust response infrastructures. Our analysis focuses on what it means for the people who sustain health systems in an emergency to be 'prepared' for an epidemic. Human preparedness entails more than the presence of a labour force; it involves building and maintaining 'relational infrastructures', often fragile social and moral relationships between health workers, publics, governments, and international organisations. The COVID-19 pandemic has underscored the value of rethinking human resources from an anthropological perspective, and investing in the safety and support of people at the forefront of response. In describing the labour, personal losses, and social risks undertaken by frontline workers for protocols and practicality to meet in an emergency context, we describe the social process of preparedness; that is, the contextual engineering and investment that make response systems work

Correction: Lassa hemorrhagic fever in a late term pregnancy from northern Sierra Leone with a positive maternal outcome: case report

Lassa fever (LF) is a devastating viral disease prevalent in West Africa. Efforts to take on this public health crisis have been hindered by lack of infrastructure and rapid field deployable diagnosis in areas where the disease is prevalent. Recent capacity building at the Kenema Government Hospital Lassa Fever Ward (KGH LFW) in Sierra Leone has lead to a major turning point in the diagnosis, treatment and study of LF. Herein we present the first comprehensive rapid diagnosis and real time characterization of an acute hemorrhagic LF case at KGH LFW. This case report focuses on a third trimester pregnant Sierra Leonean woman from the historically non-endemic Northern district of Tonkolili who survived the illness despite fetal demise. Employed in this study were newly developed recombinant LASV Antigen Rapid Test cassettes and dipstick lateral flow immunoassays (LFI) that enabled the diagnosis of LF within twenty minutes of sample collection. Deregulation of overall homeostasis, significant hepatic and renal system involvement, and immunity profiles were extensively characterized during the course of hospitalization. Rapid diagnosis, prompt treatment with a full course of intravenous (IV) ribavirin, IV fluids management, and real time monitoring of clinical parameters resulted in a positive maternal outcome despite admission to the LFW seven days post onset of symptoms, fetal demise, and a natural still birth delivery. These studies solidify the growing rapid diagnostic, treatment, and surveillance capabilities at the KGH LF Laboratory, and the potential to significantly improve the current high mortality rate caused by LF. As a result of the growing capacity, we were also able to isolate Lassa virus (LASV) RNA from the patient and perform Sanger sequencing where we found significant genetic divergence from commonly circulating Sierra Leonean strains, showing potential for the discovery of a newly emerged LASV strain with expanded geographic distribution. Furthermore, recent emergence of LF cases in Northern Sierra Leone highlights the need for superior diagnostics to aid in the monitoring of LASV strain divergence with potentially increased geographic expansion.Organismic and Evolutionary BiologyOther Research Uni

Human preparedness: Relational infrastructures and medical countermeasures in Sierra Leone.

This paper examines health worker experiences in two areas of post-epidemic preparedness in Sierra Leone - vaccine trials and laboratory strengthening - to reflect on the place of people in current models of epidemic response. Drawing on ethnographic research and interviews with health workers in the aftermath of Ebola, it explores the hopes and expectations that interventions foster for frontline workers in under-resourced health systems, and describes the unseen work involved in sustaining robust response infrastructures. Our analysis focuses on what it means for the people who sustain health systems in an emergency to be 'prepared' for an epidemic. Human preparedness entails more than the presence of a labour force; it involves building and maintaining 'relational infrastructures', often fragile social and moral relationships between health workers, publics, governments, and international organisations. The COVID-19 pandemic has underscored the value of rethinking human resources from an anthropological perspective, and investing in the safety and support of people at the forefront of response. In describing the labour, personal losses, and social risks undertaken by frontline workers for protocols and practicality to meet in an emergency context, we describe the social process of preparedness; that is, the contextual engineering and investment that make response systems work

Identifying the genetic basis of viral spillover using Lassa virus as a test case

The rate at which zoonotic viruses spill over into the human population varies significantly over space and time. Remarkably, we do not yet know how much of this variation is attributable to genetic variation within viral populations. This gap in understanding arises because we lack methods of genetic analysis that can be easily applied to zoonotic viruses, where the number of available viral sequences is often limited, and opportunistic sampling introduces significant population stratification. Here, we explore the feasibility of using patterns of shared ancestry to correct for population stratification, enabling genome-wide association methods to identify genetic substitutions associated with spillover into the human population. Using a combination of phylogenetically structured simulations and Lassa virus sequences collected from humans and rodents in Sierra Leone, we demonstrate that existing methods do not fully correct for stratification, leading to elevated error rates. We also demonstrate, however, that the Type I error rate can be substantially reduced by confining the analysis to a less-stratified region of the phylogeny, even in an already-small dataset. Using this method, we detect two candidate single-nucleotide polymorphisms associated with spillover in the Lassa virus polymerase gene and provide generalized recommendations for the collection and analysis of zoonotic viruses