The indirect health effects of malaria estimated from health advantages of the sickle cell trait.
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ABSTRACT:
SUBMITTER: Uyoga S
PROVIDER: S-EPMC6382840 | biostudies-literature | 2019 Feb
REPOSITORIES: biostudies-literature
Publications
The indirect health effects of malaria estimated from health advantages of the sickle cell trait.
Uyoga Sophie S Macharia Alex W AW Ndila Carolyne M CM Nyutu Gideon G Shebe Mohammed M Awuondo Kennedy O KO Mturi Neema N Peshu Norbert N Tsofa Benjamin B Scott J Anthony G JAG Maitland Kathryn K Williams Thomas N TN
Nature communications 20190220 1
Most estimates of the burden of malaria are based on its direct impacts; however, its true burden is likely to be greater because of its wider effects on overall health. Here we estimate the indirect impact of malaria on children's health in a case-control study, using the sickle cell trait (HbAS), a condition associated with a high degree of specific malaria resistance, as a proxy indicator for an effective intervention. We estimate the odds ratios for HbAS among cases (all children admitted to ...[more]
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Project description:Sickle Cell Trait (SCT) has been shown to be protective against malaria. A growing literature suggests that malaria exposure can reduce educational attainment. This study assessed the relationship and interactions between malaria, SCT and educational attainment in north-eastern Tanzania.Seven hundred sixty seven children were selected from a list of individuals screened for SCT. Febrile illness and malaria incidence were monitored from January 2006 to December 2013 by community health workers. Education outcomes were extracted from the Korogwe Health and Demographic Surveillance system in 2015. The primary independent variables were malaria and SCT. The association between SCT and the number of fever and malaria episodes from 2006 to 2013 was analyzed. Main outcomes of interest were school enrolment and educational attainment in 2015.SCT was not associated with school enrolment (adjusted OR 1.42, 95% CI [0.593,3.412]) or highest grade attained (adjusted grade difference 0.0597, 95% CI [-0.567, 0.686]). SCT was associated with a 29% reduction in malaria incidence (adjusted IRR 0.71, 95% CI [0.526, 0.959]) but not with fever incidence (adjusted IRR 0.905, 95% CI [0.709-1.154]). In subgroup analysis of individuals with SCT, malaria exposure was associated with reduced school enrollment (adjusted OR 0.431, 95% CI [0.212, 0.877]).SCT appears to reduce incidence of malaria. Overall, children with SCT do not appear to attend more years of school; however children who get malaria despite SCT appear to have lower levels of enrolment in education than their peers.
| S-EPMC5558763 | biostudies-other
Project description:Sickle cell disease (SCD) is a genetic disorder that poses a serious health threat in tropical Africa, which the World Health Organization has declared a public health priority. Its persistence in human populations has been attributed to the resistance it provides to Plasmodium falciparum malaria in its heterozygous state, called sickle cell trait (SCT). Because of migration, SCT is becoming common outside tropical countries: It is now the most important genetic disorder in France, affecting one birth for every 2,400, and one of the most common in the United States. We assess the strength of the association between SCT and malaria, using current data for both SCT and malaria infections. A total of 3,959 blood samples from 195 villages distributed over the entire Republic of Gabon were analyzed. Hemoglobin variants were identified by using HPLCy (HPLC). Infections by three species of Plasmodium were detected by PCR followed by sequencing of a 201-bp fragment of cytochrome b. An increase of 10% in P. falciparum malaria prevalence is associated with an increase by 4.3% of SCT carriers. An increase of 10 y of age is associated with an increase by 5.5% of SCT carriers. Sex is not associated with SCT. These strong associations show that malaria remains a selective factor in current human populations, despite the progress of medicine and the actions undertaken to fight this disease. Our results provide evidence that evolution is still present in humans, although this is sometimes questioned by scientific, political, or religious personalities.
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Project description:Sickle cell syndromes, including sickle cell disease (SCD) and sickle cell trait, are associated with multiple kidney abnormalities. Young patients with SCD have elevated effective renal plasma flow and glomerular filtration rates, which decrease to normal ranges in young adulthood and subnormal levels with advancing age. The pathophysiology of SCD-related nephropathy is multifactorial - oxidative stress, hyperfiltration and glomerular hypertension are all contributing factors. Albuminuria, which is an early clinical manifestation of glomerular damage, is common in individuals with SCD. Kidney function declines more rapidly in individuals with SCD than in those with sickle cell trait or in healthy individuals. Multiple genetic modifiers, including APOL1, HMOX1, HBA1 and HBA2 variants are also implicated in the development and progression of SCD-related nephropathy. Chronic kidney disease and rapid decline in estimated glomerular filtration rate are associated with increased mortality in adults with SCD. Renin-angiotensin-aldosterone system inhibitors are the standard of care treatment for albuminuria in SCD, despite a lack of controlled studies demonstrating their long-term efficacy. Multiple studies of novel therapeutic agents are ongoing, and patients with SCD and kidney failure should be evaluated for kidney transplantation. Given the high prevalence and severe consequences of kidney disease, additional studies are needed to elucidate the pathophysiology, natural history and treatment of SCD-related nephropathy.
| S-EPMC9832386 | biostudies-literature
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Project description:Controlled human malaria infection (CHMI) by direct venous inoculation (DVI) with 3,200 cryopreserved Plasmodium falciparum sporozoites (PfSPZ) consistently leads to parasitemia and malaria symptoms in malaria-naive adults. We used CHMI by DVI to investigate infection rates, parasite kinetics, and malaria symptoms in lifelong malaria-exposed (semi-immune) Gabonese adults with and without sickle cell trait. Eleven semi-immune Gabonese with normal hemoglobin (IA), nine with sickle cell trait (IS), and five nonimmune European controls with normal hemoglobin (NI) received 3,200 PfSPZ by DVI and were followed 28 days for parasitemia by thick blood smear (TBS) and quantitative polymerase chain reaction (qPCR) and for malaria symptoms. End points were time to parasitemia and parasitemia plus symptoms. PfSPZ Challenge was well tolerated and safe. Five of the five (100%) NI, 7/11 (64%) IA, and 5/9 (56%) IS volunteers developed parasitemia by TBS, and 5/5 (100%) NI, 9/11 (82%) IA, and 7/9 (78%) IS by qPCR, respectively. The time to parasitemia by TBS was longer in IA (geometric mean 16.9 days) and IS (19.1 days) than in NA (12.6 days) volunteers (P = 0.016, 0.021, respectively). Five of the five, 6/9, and 1/7 volunteers with parasitemia developed symptoms (P = 0.003, NI versus IS). Naturally adaptive immunity (NAI) to malaria significantly prolonged the time to parasitemia. Sickle cell trait seemed to prolong it further. NAI plus sickle cell trait, but not NAI alone, significantly reduced symptom rate. Twenty percent (4/20) semi-immunes demonstrated sterile protective immunity. Standardized CHMI with PfSPZ Challenge is a powerful tool for dissecting the impact of innate and naturally acquired adaptive immunity on malaria.
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| S-EPMC5105170 | biostudies-literature
Project description:BackgroundIndividually, the red blood cell (RBC) polymorphisms sickle cell trait (HbAS) and α+thalassemia protect against severe Plasmodium falciparum malaria. It has been shown through epidemiological studies that the co-inheritance of both conditions results in a loss of the protection afforded by each, but the biological mechanisms remain unknown.MethodsWe used RBCs from >300 donors of various HbAS and α+thalassemia genotype combinations to study the individual and combinatorial effects of these polymorphisms on a range of putative P. falciparum virulence phenotypes in-vitro, using four well-characterised P. falciparum laboratory strains. We studied cytoadhesion of parasitized RBCs (pRBCs) to the endothelial receptors CD36 and ICAM1, rosetting of pRBCs with uninfected RBCs, and pRBC surface expression of the parasite-derived adhesion molecule P. falciparum Erythrocyte Membrane Protein-1 (PfEMP1).FindingsWe confirmed previous reports that HbAS pRBCs show reduced cytoadhesion, rosetting and PfEMP1 expression levels compared to normal pRBC controls. Furthermore, we found that co-inheritance of HbAS with α+thalassemia consistently reversed these effects, such that pRBCs of mixed genotype showed levels of cytoadhesion, rosetting and PfEMP1 expression indistinguishable from those seen in normal pRBCs. However, pRBCs with α+thalassemia alone showed parasite strain-specific effects on adhesion, and no consistent reduction in PfEMP1 expression.InterpretationOur data support the hypothesis that the negative epistasis between HbAS and α+thalassemia observed in epidemiological studies might be explained by host genotype-specific changes in the pRBC-adhesion properties that contribute to parasite sequestration and disease pathogenesis in vivo. The mechanism by which α+thalassemia on its own protects against severe malaria remains unresolved.
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Project description:Background and objectivesSickle cell trait and sickle cell disease are associated with faster GFR decline compared with normal hemoglobin phenotypes. We sought to compare the AKI risk in sickle cell trait/disease to normal hemoglobin phenotypes and investigate the association between AKI and GFR decline in sickle cell trait/disease.Design, setting, participants, & measurementsThis multicenter observational study used registry data (January 2005-June 2018) of adult Black patients with sickle cell trait/disease (exposures) and normal hemoglobin phenotype (reference) ascertained by hemoglobin electrophoresis. Outcomes of interest (incident AKI [1.5 times baseline serum creatinine or higher], incident severe AKI [doubling of baseline serum creatinine or higher], and incident sustained AKI [AKI persisting for ≥72 hours]) were adjudicated by chart review and evaluated by Cox regression. The association between AKI and GFR decline (linear mixed models) was also investigated.ResultsWe identified 8968 reference patients, 1279 patients with sickle cell trait, and 254 patients with sickle cell disease with a median follow-up of 7.6 years and mean baseline serum creatinine of 0.8 mg/dl. We observed 796 AKI events, 452 sustained AKI events, and 466 severe AKI events. Compared with people with a normal hemoglobin phenotype, sickle cell trait was associated with higher risk for sustained AKI (adjusted hazard ratio, 1.64; 95% confidence interval, 1.27 to 2.11), but not AKI (adjusted hazard ratio, 1.11; 95% confidence interval, 0.91 to 1.36) or severe AKI (adjusted hazard ratio, 1.26; 95% confidence interval, 0.96 to 1.64). Sickle cell disease was associated with AKI (adjusted hazard ratio, 2.85; 95% confidence interval, 2.13 to 3.81), severe AKI (adjusted hazard ratio, 2.38; 95% confidence interval, 1.65 to 3.42), and sustained AKI (adjusted hazard ratio, 2.50; 95% confidence interval, 1.68 to 3.71). Post-AKI GFR decline was significantly faster in sickle cell trait (0.37 ml/min per 1.73 m2 per year faster, P<0.01) and disease (1.69 ml/min per 1.73 m2 per year faster, P<0.01) compared with the reference.ConclusionsSickle cell trait and disease are associated with higher risk of AKI, which is associated with accelerated decline in eGFR.
| S-EPMC8011026 | biostudies-literature
Project description:BackgroundClinical manifestations and severity of SARS-CoV-2 infection in individuals with sickle cell disease (SCD) and sickle cell trait (SCT) are not well understood yet.MethodsWe performed a systematic review and meta-analysis to assess COVID-19 outcomes in individuals with SCD or SCT compared to individuals without sickle cell disease or trait. An electronic search on PubMed, Embase, and Cochrane Library was performed on August 3, 2023. Two authors (IFM and ISP) independently screened (IFM and ISP) and extracted data (IFM and ILC) from included studies. Main exclusion criterion was the absence of the non-SCD/SCT group. Exposure effects for binary endpoints were compared using pooled odds ratio (OR) with 95% confidence intervals (CI). I2 statistics was used to assess the heterogeneity and DerSimonian and Laird random-effects models were applied for all analyses to minimize the impact of differences in methods and outcomes definitions between studies. The overall quality of evidence was assessed using the GRADE system. Review Manager 5.4 and R software (v4.2.2) were used for statistical analyses. Registered with PROSPERO, CRD42022366015.FindingsOverall, 22 studies were included, with a total of 1892 individuals with SCD, 8677 individuals with SCT, and 1,653,369 individuals without SCD/SCT. No difference in all-cause mortality was seen between SCD/SCT and non-SCD/SCT (OR 1.18; 95% CI 0.78-1.77; p = 0.429; I2 = 82%). When considering only studies adjusted for confounders (8 studies), patients with SCD/SCT were shown to be at increased risk of death (OR 1.86; 95% CI 1.30-2.66; p = 0.0007; I2 = 34%). No significant difference was seen between individuals with SCD and SCT (p = 0.863). The adjusted for confounders analysis for hospitalisation revealed higher rates for the SCD (OR 5.44; 95% CI 1.55-19.13; p = 0.008; I2 = 97%) and the SCT groups (OR 1.31; 95% CI 1.10-1.55; p = 0.002; I2 = 0) compared to the non-SCD/SCT population. Moreover, it was significantly higher for the SCD group (test for subgroup difference; p = 0.028).InterpretationOur findings suggest that patients with SCD or SCT may present with a higher mortality and hospitalisation rates due to COVID-19 infection.FundingNone.
| S-EPMC10755716 | biostudies-literature
Project description:The sickle hemoglobin (HbS) point mutation has independently undergone evolutionary selection at least five times in the world because of its overwhelming malarial protective effects in the heterozygous state. In 1949, homozygous Hb S or sickle cell disease (SCD) became the first inherited condition identified at the molecular level; however, since then, both SCD and heterozygous Hb S, sickle cell trait (SCT), have endured a long and complicated history. Hasty adoption of early mass screening programs for SCD, recent implementation of targeted screening mandates for SCT in athletics, and concerns about stigmatization have evoked considerable controversy regarding research and policy decisions for SCT. Although SCT is a largely protective condition in the context of malaria, clinical sequelae, such as exercise-related injury, renal complications, and venous thromboembolism can occur in affected carriers. The historical background of SCD and SCT has provided lessons about how research should be conducted in the modern era to minimize stigmatization, optimize study conclusions, and inform genetic counseling and policy decisions for SCT.
| S-EPMC4697437 | biostudies-literature