Morbidity associated with sickle cell trait carriers

Background: Sickle cell trait carriers has long considered asymptomatic. This affirmation is now challenged because many patients complain of osteoarticular pain and several organic degenerative complications in particular; renal, eye and sudden death have been described. The objective of this study was to evaluate the morbidity of sickle cell trait and identify risk factors associated.Methods: This is a prospective study with duration of 16 months including 50 patients with sickle cell trait received regular visits (every 6 months) for painful events. Biological assessment was carried out systematically to eliminate rheumatic disease (CRP, ASLO, latex Waler Rose) or metabolic disorders (serum calcium, serum magnesium, and serum uric acid). A correlation between clinical and laboratory data was performed to study the relationship between morbidity observed and biological abnormalities.Results: Mean age of patients was 32 years (12-59) and mean age at diagnosis was 24 years (12-55 years). Sex ratio M/F was 0.16. Clinical symptoms were osteoarticular pain (88%), headache (86%), abdominal pain (76%), muscle cramps (70%), dizziness (56%), biliary lithiasis (6%), femoral head osteonecrosis (2%) and gross haematuria (2%). Seventeen patients (34%) had abnormal metabolic or rheumatic analysis. No risk factor associated with morbidity of patients was identified.Conclusions: This work has allowed us to find that the symptoms presented by sickle cell trait patients are dominated by painful events. This morbidity associated with porting sickle cell trait was not secondary to inflammatory or metabolic disorders or physical activity

Malaria Transmission Pattern in an Area Selected for Clinical Trials in the Sudanian Area of Senegal (West Africa)

Malaria transmission pattern was studied in 3 villages (Toubanding, Daga Ndoup, and Keur Samba Guèye) situated within an area selected for clinical trials. The study was conducted in the rainy season from July to December 2011. The main objective of this work was to gather baseline data on malaria transmission intensity and other entomological parameters before the advent of clinical trials. Mosquitoes were collected by Human-Landing Collections (HLCs) and by pyrethrum spray catches (PSCs). Five anopheline species were collected, namely, An. arabiensis, An. gambiae, An. funestus, An. pharoensis, and An. rufipes, giving a heterogeneous distribution within the study area. The populations dynamics of the vectors varied temporarily in each village depending on the pattern of the rainy season. Transmission intensity estimated by the entomological inoculation rate (EIR) was measured in each of the three villages with the variations linked to the microecological differences between the villages. Measurements were calculated for August, September, and October and were found to vary between 4 and 30 infected bites per person over the study period with a peak intensity observed in September. These results indicate that epidemiological field trials on malaria could be conducted in this area on the basis of the differences observed with transmission intensity, micro-ecological variations, and the objectives of the trials

The evolving SARS-CoV-2 epidemic in Africa: Insights from rapidly expanding genomic surveillance

INTRODUCTION Investment in Africa over the past year with regard to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) sequencing has led to a massive increase in the number of sequences, which, to date, exceeds 100,000 sequences generated to track the pandemic on the continent. These sequences have profoundly affected how public health officials in Africa have navigated the COVID-19 pandemic. RATIONALE We demonstrate how the first 100,000 SARS-CoV-2 sequences from Africa have helped monitor the epidemic on the continent, how genomic surveillance expanded over the course of the pandemic, and how we adapted our sequencing methods to deal with an evolving virus. Finally, we also examine how viral lineages have spread across the continent in a phylogeographic framework to gain insights into the underlying temporal and spatial transmission dynamics for several variants of concern (VOCs). RESULTS Our results indicate that the number of countries in Africa that can sequence the virus within their own borders is growing and that this is coupled with a shorter turnaround time from the time of sampling to sequence submission. Ongoing evolution necessitated the continual updating of primer sets, and, as a result, eight primer sets were designed in tandem with viral evolution and used to ensure effective sequencing of the virus. The pandemic unfolded through multiple waves of infection that were each driven by distinct genetic lineages, with B.1-like ancestral strains associated with the first pandemic wave of infections in 2020. Successive waves on the continent were fueled by different VOCs, with Alpha and Beta cocirculating in distinct spatial patterns during the second wave and Delta and Omicron affecting the whole continent during the third and fourth waves, respectively. Phylogeographic reconstruction points toward distinct differences in viral importation and exportation patterns associated with the Alpha, Beta, Delta, and Omicron variants and subvariants, when considering both Africa versus the rest of the world and viral dissemination within the continent. Our epidemiological and phylogenetic inferences therefore underscore the heterogeneous nature of the pandemic on the continent and highlight key insights and challenges, for instance, recognizing the limitations of low testing proportions. We also highlight the early warning capacity that genomic surveillance in Africa has had for the rest of the world with the detection of new lineages and variants, the most recent being the characterization of various Omicron subvariants. CONCLUSION Sustained investment for diagnostics and genomic surveillance in Africa is needed as the virus continues to evolve. This is important not only to help combat SARS-CoV-2 on the continent but also because it can be used as a platform to help address the many emerging and reemerging infectious disease threats in Africa. In particular, capacity building for local sequencing within countries or within the continent should be prioritized because this is generally associated with shorter turnaround times, providing the most benefit to local public health authorities tasked with pandemic response and mitigation and allowing for the fastest reaction to localized outbreaks. These investments are crucial for pandemic preparedness and response and will serve the health of the continent well into the 21st century

Homozygous sickle cell disease related mortality in Senegal (2011–2020)

Abstract Homozygous sickle cell disease (HSCD) is characterized by multiorgan morbidity and an increased risk of early death. We aim to describe the mortality rate, causes, and risk factors of death in HSCD between 2011 and 2020. We conducted a retrospective study with a duration of 10 years in the cohort of 2348 HSCD patients. The mortality rate was determined by reporting the number of deaths to the total number of patients followed in the year. Sociodemographic, clinical, biological data and causes of death were studied. Death risk factors were determined by a bivariate analysis comparing deceased and living HSCD patients. The mean age of death was 26 years (3–52). The sex ratio was 1.2. The mortality rate was 2.76%. The death rate was high in 2011 (3.2%) and low in 2020 (0.17%). We observed a significant reduction of mortality of 94.6%. Most of the common causes of death were acute anemia (40%), acute chest syndrome (24.6%), and infections (20%). Risk factors of death were age, vaso‐occlusive crises ≥3, acute chest syndrome, blood transfusion, and chronic complications. Mortality among HSCD has significantly decreased over the past 10 years in Senegal, and the main causes of death were acute anemia, acute chest syndrome, and infections

Use of HRP-2-based rapid diagnostic test for <it>Plasmodium falciparum </it>malaria: assessing accuracy and cost-effectiveness in the villages of Dielmo and Ndiop, Senegal

Abstract Background In 2006, the Senegalese National Malaria Control Programme (NMCP) has recommended artemisinin-based combination therapy (ACT) as the first-line treatment for uncomplicated malaria and, in 2007, mandated testing for all suspected cases of malaria with a Plasmodium falciparum HRP-2-based rapid diagnostic test for malaria (RDT(Paracheck®). Given the higher cost of ACT compared to earlier anti-malarials, the objectives of the present study were i) to study the accuracy of Paracheck® compared to the thick blood smear (TBS) in two areas with different levels of malaria endemicity and ii) analyse the cost-effectiveness of the strategy of the parasitological confirmation of clinically suspected malaria cases management recommended by the NMCP. Methods A cross-sectional study was undertaken in the villages of Dielmo and Ndiop (Senegal) nested in a cohort study of about 800 inhabitants. For all the individuals consulting between October 2008 and January 2009 with a clinical diagnosis of malaria, a questionnaire was filled and finger-prick blood samples were taken both for microscopic examination and RDT. The estimated costs and cost-effectiveness analysis were made considering five scenarios, the recommendations of the NMCP being the reference scenario. In addition, a sensitivity analysis was performed assuming that all the RDT-positive patients and 50% of RDT-negative patients were treated with ACT. Results A total of 189 consultations for clinically suspected malaria occurred during the study period. The sensitivity, specificity, positive and negative predictive values were respectively 100%, 98.3%, 80.0% and 100%. The estimated cost of the reference scenario was close to 700€ per 1000 episodes of illness, approximately twice as expensive as most of the other scenarios. Nevertheless, it appeared to us cost-effective while ensuring the diagnosis and the treatment of 100% of malaria attacks and an adequate management of 98.4% of episodes of illness. The present study also demonstrated that full compliance of health care providers with RDT results was required in order to avoid severe incremental costs. Conclusions A rational use of ACT requires laboratory testing of all patients presenting with presumed malaria. Use of RDTs inevitably has incremental costs, but the strategy associating RDT use for all clinically suspected malaria and prescribing ACT only to patients tested positive is cost-effective in areas where microscopy is unavailable.</p

Age-group profiles of Ab responses against <i>Plasmodium</i> and <i>A</i>. <i>gambiae</i> antigens from 2010 to 2013.

<p>Antibody responses measured by magnetic bead based fluorescence assay are plotted as Median fluorescence levels from 2010 to 2013 for individuals from 4 different age groups: < 5 years old (empty), 6-10yo (light grey), 11–15 years old (dark grey), >15 years old (black). On this figure are plotted antibody responses to <i>P</i>.<i>falciparum</i> Ags tested not shown on <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0172899#pone.0172899.g003" target="_blank">Fig 3</a> together with <i>P</i>. <i>malariae</i> CSP and <i>A gambiae</i> salivary peptide gSG6.</p

Context and characteristics of the study population.

<p>Context and characteristics of the study population.</p