High mortality from Plasmodium falciparum malaria in children living with sickle cell anemia on the coast of Kenya

Characterization of a cohort of Angolan children with sickle cell anemia treated with hydroxyurea

BACKGROUND

Sickle Cell Anemia (SCA) is a monogenic disease, although its severity and response to treatment are very heterogeneous.

OBJECTIVES

This study aims to characterize a cohort of Angolan children with SCA and evaluate their response to hydroxyurea (HU) treatment and the potential side effects and toxicity.

METHODS

The study enrolled 215 patients between 3 and 12 years old before and after the administration of HU, at a fix dose of 20 mg/kg/day for 12 months.

RESULTS

A total of 157 patients started HU medication and 141 of them completed the 12-month treatment. After initiating HU treatment, the frequency of clinical events decreased (transfusions 53.4 %, hospitalizations 47.1 %). The response to HU medication varied among patients, with some experiencing an increase in fetal hemoglobin (HbF) of <5 %. The mean increase in HbF was 11.9 %, ranging from 1.8 % to 31 %. Responders to HU treatment were 57 %, inadequate responders 38.7 % and non-adherent 4.2 %. No clinical side effects related to HU were reported. Hematological toxicities were transient and reversible. Children naïve to HU and with lower HbF reported higher number of hospitalizations caused by malaria infection. During HU treatment, the frequency of malaria episodes did not appear to be affected by HbF levels.

CONCLUSIONS

the present study provided a valuable contribution to the understanding of the clinical and laboratory profiles of Angolan children with SCA. These findings support the evidence that the implementation of prophylactic measures and treatment with HU is associated with increased survival in children with SCA.

Malaria Infection in Patients with Sickle Cell Disease in Nigeria: Association with Markers of Hyposplenism

Malaria is considered an important cause of morbidity and mortality among people living with sickle cell disease (SCD). This has partly been attributed to the loss of splenic function that occurs early in the disease process. We conducted a cross-sectional study and determined the frequency of malaria infection among SCD patients and explored the association with spleen's presence on ultrasonography and spleen function assessed using the frequency of Howell-Jolly bodies (HJBs). A total of 395 participants consisting of 119 acutely-ill SCD patients, 168 steady-state SCD controls, and 108 healthy non-SCD controls were studied. The prevalence of Plasmodium falciparum parasitemia was 51.3% in acutely-ill SCD patients, 31.7% in steady-state SCD controls, and 11.0% in the healthy non-SCD controls; however, the mean parasite density was significantly higher in the non-SCD controls compared to both SCD groups (p = 0.0001). Among the acutely-ill SCD patients, the prevalence of clinical malaria and severe malaria anemia were highest in children <5 years of age. The prevalence of parasitemia (p = 0.540) and parasite density (p = 0.975) showed no association with spleen presence or absence on ultrasonography. Similarly, the frequency of HJB red cells was not associated with the presence of parasitemia (p = 0.183). Our study highlights the frequency and role of malaria infection in acutely-ill SCD patients, especially in those younger than five years. Although we have found no evidence of an increased risk of malaria parasitemia or parasite density with markers of hyposplenism, the role played by an underlying immunity to malaria among SCD patients in malaria-endemic region is not clear and needs further studies.

Evaluation of treatment patterns, healthcare resource utilization and cost of illness for sickle cell disease in Ghana: a private medical insurance claims database study

BACKGROUND

Sickle cell disease (SCD) is a major public health concern in sub-Saharan Africa, accounting for nearly 75% of the global disease burden. The current analysis evaluated patient characteristics, treatment patterns, healthcare resource utilization (HCRU) and associated costs in patients with SCD based on a Private Medical Insurance Database in Ghana.

METHODS

This retrospective longitudinal cohort study was conducted using an e-claims database from Ghana (01 January 2015 to 31 March 2021). Patients were stratified by age (0 month to < 2 years, ≥ 2 years to ˂6 years, ≥ 6 years to < 12 years, ≥ 12 years to < 16 years; ≥16 years), vaso-occlusive crisis (VOC) (< 1, ≥ 1 to < 3, and ≥ 3 per year), and continuous enrolment. Study outcomes related to patient characteristics, comorbidities, treatment pattern, HCRU were evaluated for pre- and post-index period (index period was between July 2015 to March 2020). Descriptive analysis was used to analyse different study variables.

RESULTS

The study included 2,863 patients (mean age: 20.1 years; Min age: 0; Max age: 83; females 56.1%). Overall, 52.2% (n = 1,495) of SCD patients were ≥ 16 years and 17.0% (n = 486) were in the ≥ 2 to ˂6-years age group. The majority of patients aged ≥ 16 years (62.5%) in the database did not have reported VOC episodes, 35.9% of patients had 1 to 3 VOCs per year and 1.5% had ≥ 3 VOCs per year during the follow-up period. Consultation-based prevalence of SCD was 0.5% [95% confidence interval (CI): 0-1.3%] - 1.4% [CI: 0.6-2.2%]. Malaria, upper respiratory tract infection (URTI) and sepsis were the common complications of SCD. Analgesics were the most frequently prescribed medications followed by anti-infectives, hematinics, and antimalarials. Hydroxyurea, a routine standard of care for SCD was under-utilized. SCD patients had median cost incurred for consultation/hospital services of $11.3 (Interquartile range [IQR] $6.2 - $27.2). For patients with VOC, maximum median cost was incurred for medications ($10.9 [IQR $5.0-$32.6]). Overall median healthcare cost was highest for individuals with ≥ 3 VOCs per year during the follow-up period ($166.8 [IQR $70.3-$223.5]).

CONCLUSION

In this retrospective private insurance claims database analysis, SCD imposes a significant healthcare burden, especially in patients with VOC. There is a need for reimbursed treatment options that could reduce the long-term burden associated with SCD and VOC.

Case Report: A Case of Bone Marrow Necrosis and Hyperinflammation in a 10-Year-Old Boy after Plasmodium falciparum Infection

A 10-year-old boy with sickle cell disease (SCD) type SC presented with fever and abdominal pain after travel to Ghana and was diagnosed with Plasmodium falciparum infection. Despite adequate antimalarial treatment, he developed evidence of hyperinflammation with marked elevated ferritin, C-reactive protein, and triglycerides and subsequent bone marrow necrosis, characterized by elevated nucleated red blood cells and significant bone pain. This case report highlights the possible association between malaria and bone marrow necrosis in patients with SCD. Important considerations in treatment and workup of patients presenting with malaria and hyperinflammation are discussed.

A Journey from Blood Cells to Genes and Back

I was attracted to hematology because by combining clinical findings with the use of a microscope and simple laboratory tests, one could often make a diagnosis. I was attracted to genetics when I learned about inherited blood disorders, at a time when we had only hints that somatic mutations were also important. It seemed clear that if we understood not only what genetic changes caused what diseases but also the mechanisms through which those genetic changes contribute to cause disease, we could improve management. Thus, I investigated many aspects of the glucose-6-phosphate dehydrogenase system, including cloning of the gene, and in the study of paroxysmal nocturnal hemoglobinuria (PNH), I found that it is a clonal disorder; subsequently, we were able to explain how a nonmalignant clone can expand, and I was involved in the first trial of PNH treatment by complement inhibition. I was fortunate to do clinical and research hematology in five countries; in all of them, I learned from mentors, from colleagues, and from patients.

Dihydroartemisinin-piperaquine or sulphadoxine-pyrimethamine for the chemoprevention of malaria in children with sickle cell anaemia in eastern and southern Africa (CHEMCHA): a protocol for a multi-centre, two-arm, double-blind, randomised, placebo-controlled superiority trial

BACKGROUND

An estimated 300,000 babies are born with sickle cell anaemia (SCA) annually. Affected children have chronic ill health and suffer premature death. Febrile illnesses such as malaria commonly precipitate acute crises in children with SCA. Thus, chemoprophylaxis for malaria is an important preventive strategy, but current regimes are either sub-optimally effective (e.g. monthly sulphadoxine-pyrimethamine, SP) or difficult to adhere to (e.g. daily proguanil). We propose dihydroartemisinin-piperaquine (DP) as the agent with the most potential to be used across Africa.

METHODS

This will be a randomised, double-blind, parallel-group superiority trial of weekly single-day courses of DP compared to monthly single-day courses of SP in children with SCA. The study will be conducted in eastern (Uganda) and southern (Malawi) Africa using randomisation stratified by body weight and study centre. Participants will be randomised using an allocation of 1:1 to DP or SP. We will investigate the efficacy, safety, acceptability and uptake and cost-effectiveness of malaria chemoprevention with weekly courses of DP vs monthly SP in 548 to 824 children with SCA followed up for 12-18 months. We will also assess toxicity from cumulative DP dosing and the development of resistance. Participant recruitment commenced on 30 April 2021; follow-up is ongoing.

DISCUSSION

At the end of this study, findings will be used to inform regional health policy. This manuscript is prepared from protocol version 2.1 dated 1 January 2022.

TRIAL REGISTRATION

The trial was registered at ClinicalTrials.gov, NCT04844099 . Registered on 08 April 2021.

Hydroxyurea treatment is associated with lower malaria incidence in children with sickle cell anemia in sub-Saharan Africa

Realizing Effectiveness Across Continents with Hydroxyurea (REACH, NCT01966731) provides hydroxyurea at maximum tolerated dose (MTD) for children with sickle cell anemia (SCA) in sub-Saharan Africa. Beyond reducing SCA-related clinical events, documented treatment benefits include ∼50% reduction in malaria incidence. To identify associations and propose mechanisms by which hydroxyurea could be associated with lower malaria rates, infections were recorded across all clinical sites (Angola, Democratic Republic of Congo, Kenya, and Uganda). Hazard ratios (HR) with 95% confidence intervals (CIs) for baseline demographics, and time-varying laboratory and clinical parameters were estimated in a modified Cox gap-time model for repeated events. Over 3387 patient-years of hydroxyurea treatment, 717 clinical malaria episodes occurred in 336 of 606 study participants; over half were confirmed by blood smear and/or rapid diagnostic testing with 97.8% Plasmodium falciparum. In univariate analysis limited to 4 confirmed infections per child, malaria risk was significantly associated with absolute neutrophil count (ANC), splenomegaly, hemoglobin, and achieving MTD; age, malaria season, MTD dose, fetal hemoglobin, α-thalassemia, and glucose-6-phosphate dehydrogenase deficiency had no effect. In multivariable regression of confirmed infections, ANC was significant (HR, 1.37 per doubled value; 95% CI, 1.10-1.70; P = .0052), and ANC values <3.0 × 109/L were associated with lower malaria incidence. Compared with nonpalpable spleen, 1- to 4-cm splenomegaly also was associated with higher malaria risk (HR, 2.01; 95% CI, 1.41-2.85; P = .0001). Hydroxyurea at MTD is associated with lower malaria incidence in SCA through incompletely defined mechanisms, but treatment-associated mild myelosuppression with ANC <3.0 × 109/L is salutary. Splenomegaly is an unexplained risk factor for malaria infections among children with SCA in Africa.

Monthly sulfadoxine/pyrimethamine-amodiaquine or dihydroartemisinin-piperaquine as malaria chemoprevention in young Kenyan children with sickle cell anemia: A randomized controlled trial

BACKGROUND

Children with sickle cell anemia (SCA) in areas of Africa with endemic malaria transmission are commonly prescribed malaria chemoprevention. Chemoprevention regimens vary between countries, and the comparative efficacy of prevention regimens is largely unknown.

METHODS AND FINDINGS

We enrolled Kenyan children aged 1 to 10 years with homozygous hemoglobin S (HbSS) in a randomized, open-label trial conducted between January 23, 2018, and December 15, 2020, in Homa Bay, Kenya. Children were assigned 1:1:1 to daily Proguanil (the standard of care), monthly sulfadoxine/pyrimethamine-amodiaquine (SP-AQ), or monthly dihydroartemisinin-piperaquine (DP) and followed monthly for 12 months. The primary outcome was the cumulative incidence of clinical malaria at 12 months, and the main secondary outcome was the cumulative incidence of painful events by self-report. Secondary outcomes included other parasitologic, hematologic, and general events. Negative binomial models were used to estimate incidence rate ratios (IRRs) per patient-year (PPY) at risk relative to Proguanil. The primary analytic population was the As-Treated population. A total of 246 children were randomized to daily Proguanil (n = 81), monthly SP-AQ (n = 83), or monthly DP (n = 82). Overall, 53.3% (n = 131) were boys and the mean age was 4.6 ± 2.5 years. The clinical malaria incidence was 0.04 episodes/PPY; relative to the daily Proguanil group, incidence rates were not significantly different in the monthly SP-AQ (IRR: 3.05, 95% confidence interval [CI]: 0.36 to 26.14; p = 0.39) and DP (IRR: 1.36, 95% CI: 0.21 to 8.85; p = 0.90) groups. Among secondary outcomes, relative to the daily Proguanil group, the incidence of painful events was not significantly different in the monthly SP-AQ and DP groups, while monthly DP was associated with a reduced rate of dactylitis (IRR: 0.47; 95% CI: 0.23 to 0.96; p = 0.038). The incidence of Plasmodium falciparum infection relative to daily Proguanil was similar in the monthly SP-AQ group (IRR 0.46; 95% CI: 0.17 to 1.20; p = 0.13) but reduced with monthly DP (IRR 0.21; 95% CI: 0.08 to 0.56; p = 0.002). Serious adverse events were common and distributed between groups, although compared to daily Proguanil (n = 2), more children died receiving monthly SP-AQ (n = 7; hazard ratio [HR] 5.44; 95% CI: 0.92 to 32.11; p = 0.064) but not DP (n = 1; HR 0.61; 95% CI 0.04 to 9.22; p = 0.89), although differences did not reach statistical significance for either SP-AQ or DP. Study limitations include the unexpectedly limited transmission of P. falciparum in the study setting, the high use of hydroxyurea, and the enhanced supportive care for trial participants, which may limit generalizability to higher-transmission settings where routine sickle cell care is more limited.

CONCLUSIONS

In this study with limited malaria transmission, malaria chemoprevention in Kenyan children with SCA with monthly SP-AQ or DP did not reduce clinical malaria, but DP was associated with reduced dactylitis and P. falciparum parasitization. Pragmatic studies of chemoprevention in higher malaria transmission settings are warranted.

TRIAL REGISTRATION

clinicaltrials.gov (NCT03178643). Pan-African Clinical Trials Registry: PACTR201707002371165.

The effect of sickle cell genotype on the pharmacokinetic properties of artemether-lumefantrine in Tanzanian children

Since there are inconsistent data relating to the effect of haemoglobinopathies on disposition of artemisinin antimalarial combination therapy, and none in sickle cell trait (SCT) or sickle cell disease (SCD), the aim of this study was to characterize the pharmacokinetic properties of artemether-lumefantrine (ARM-LUM) in children with SCD/SCT. Thirty-eight Tanzanian children aged 5–10 years with normal (haemoglobin AA; n = 12), heterozygous (haemoglobin AS; n = 14) or homozygous (haemoglobin SS; n = 12) sickle genotypes received six ARM-LUM doses (1.7 mg/kg plus 10 mg/kg, respectively) over 3 days. Sparse venous and mixed-capillary dried blood spot (DBS) samples were taken over 42 days. Plasma and DBS ARM and LUM, and their active metabolites dihydroartemisinin (DHA) and desbutyl-lumefantrine (DBL), were assayed using validated liquid chromatography-mass spectrometry. Multi-compartmental pharmacokinetic models were developed using a population approach. Plasma but not DBS concentrations of ARM/DHA were assessable. The majority (85%) of the 15 measurable values were within 95% prediction intervals from a published population pharmacokinetic ARM/DHA model in Papua New Guinean children of similar age without SCD/SCT who had uncomplicated malaria, and there was no clear sickle genotype clustering. Plasma (n = 38) and corrected DBS (n = 222) LUM concentrations were analysed using a two-compartment model. The median [inter-quartile range] LUM AUC_0–∞ was 607,296 [426,480–860,773] μg.h/L, within the range in published studies involving different populations, age-groups and malaria status. DBS and plasma DBL concentrations correlated poorly and were not modelled. These data support use of the conventional ARM-LUM treatment regimen for uncomplicated malaria in children with SCT/SCD.

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Malaria remains a serious infection in children with sickle cell trait/disease.

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Artemether-lumefantrine (AL) is first-line therapy in this situation.

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There are no AL pharmacokinetic data in children with sickle cell disease/trait.

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AL disposition in Tanzanian children did not differ across sickle genotypes.

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Recommended AL treatment doses can be given regardless of sickle status.

Malaria vaccine: The lasting solution to malaria burden in Africa

Malaria is one of the deadliest infectious diseases in Africa. Many measures have been taken over the past few years to reduce the burden of malaria on public health following the recommendation of WHO, still, malaria has continued to rake devastation in Africa. Combating malaria in Africa has grown into an international concern. The eradication of malaia is a long-standing goal of public health initiatives globally. The development of vaccines will go a long way to provide the required immunity needed for the people living with malaria or vulnerable to malaria. It is imperative that a vaccine should be produced and rolled out for use, especially during the time of the COVID-19 pandemic when attention is given to mitigating the impact of the pandemic on public health. The malaria vaccine will reduce the number of hospital admission for malaria illness among children and other age groups. Africa will need to build strong innovations to overcome country-specific challenges in vaccination drive, human resources, and supply chain management. Accelerating education, sensitization, diagnosis, and eradication through joint efforts of the government, healthcare professionals and general population will help to prevent the dual synchronous epidemic of COVID-19 and Malaria in Africa.

Determinants of severity in sickle cell disease

Sickle cell disease is a very variable condition, with outcomes ranging from death in childhood to living relatively symptom free into the 8^th decade. Much of this variability is unexplained. The co-inheritance of α thalassaemia and factors determining HbF levels significantly modify the phenotype, but few other significant genetic variants have been identified, despite extensive studies. Environmental factors are undoubtedly important, with socio-economics and access to basic medical care explaining the huge differences in outcomes between many low- and high-income countries. Exposure to cold and windy weather seems to precipitate acute complications in many people, although these effects are unpredictable and vary with geography. Many studies have tried to identify prognostic factors which can be used to predict outcomes, particularly when applied in infancy. Overall, low haemoglobin, low haemoglobin F percentage and high reticulocytes in childhood are associated with worse outcomes, although again these effects are fairly weak and inconsistent.

A predictive algorithm for identifying children with sickle cell anemia among children admitted to hospital with severe anemia in Africa

Sickle cell anemia (SCA) is common in sub-Saharan Africa where approximately 1% of births are affected. Severe anemia is a common cause for hospital admission within the region yet few studies have investigated the contribution made by SCA. The Transfusion and Treatment of severe anemia in African Children Trial (ISRCTN84086586) investigated various treatment strategies in 3983 children admitted with severe anemia (hemoglobin < 6.0 g/dl) based on two severity strata to four hospitals in Africa (three Uganda and one Malawi). Children with known-SCA were excluded from the uncomplicated stratum and capped at 25% in the complicated stratum. All participants were genotyped for SCA at trial completion. SCA was rare in Malawi (six patients overall), so here we focus on the participants recruited in Uganda. We present baseline characteristics by SCA status and propose an algorithm for identifying children with unknown-SCA. Overall, 430 (12%) and 608 (17%) of the 3483 Ugandan participants had known- or unknown-SCA, respectively. Children with SCA were less likely to be malaria-positive and more likely to have an affected sibling, have gross splenomegaly, or to have received a previous blood transfusion. Most outcomes, including mortality and readmission, were better in children with either known or unknown-SCA than non-SCA children. A simple algorithm based on seven admission criteria detected 73% of all children with unknown-SCA with a number needed to test to identify one new SCA case of only two. Our proposed algorithm offers an efficient and cost-effective approach to identifying children with unknown-SCA among all children admitted with severe anemia to African hospitals where screening is not widely available.

Attitudes and practices of unmarried adults towards sickle cell disease: emergent factors from a cross sectional study in Nigeria's capital

INTRODUCTION

Sickle cell disease is a genetic autosomal blood disorder that causes red blood cells to turn rigid and crescent shaped. The condition ultimately results to several complications leading to organ damage. This study aimed at assessing attitudes and practices of unmarried adults towards sickle cell disease.

METHODS

A cross sectional study was undertaken in the Nigerian Federal Capital Territory. Data were collected using a well-structured questionnaire. Descriptive and inferential statistics were undertaken.

RESULTS

Male and female participants were of a similar proportion as represented by 52% and 48%. The overall mean score for attitude towards sickle disease was 6.60 ± 2.583 (range; 0-11). A higher attitude score was observed among female participants (p = 0.012), older participants reported a better attitude towards sickle cell disease (p < 0.001), and level of education also influenced perception towards the disease (p < 0.001). Three-quarters of the participants (73.4%) supported the need for contextual legislation to prohibit marriage between two sickle cell carriers. More than one-tenth of the sample (14.4%) indicated that they would marry someone with sickle cell disease irrespective of their own genotype. Whilst two-thirds of the study participants (67.1%) indicated that they would prioritise sickle cell screening in their relationships, a third of them (33.3%) expressed a contrary standpoint.

CONCLUSION

Findings emanating from this research can guide Government and other critical Stakeholders in developing contextual policies and practices that will reduce the burden of sickle cell disorder.

Performance of an HRP-2 based (First Response®) and p-LDH-based (Optimal®) rapid diagnostic tests for diagnosis of malaria in paediatric sickle cell disease patients

BACKGROUND

Rapid diagnostic tests (RDTs) have been extensively evaluated and play an important role in malaria diagnosis. However, the accuracy of RDT for malaria diagnosis in patients with sickle cell disease (SCD) is unknown.

METHODS

We compared the performance of a histidine rich protein 2 (HRP-2) - based RDT (First Response®), and a lactate dehydrogenase (LDH) - based RDT (Optimal®) with routine microscopy as reference standard in 445 SCD children with an acute febrile illness in Accra, Ghana.

RESULTS

The overall sensitivity, specificity, positive and negative predictive values of the HRP-2 based RDT were, 100%, 95.7%, 73.8% and 100%, respectively. Comparable values for the LDH based RDT were, 91.7%, 99.5%, 95.7% and 99.0% respectively. A total of 423 results were true in both tests, one result was false in both tests, 16 results were false in the HRP-2 test only and 5 were false in the LDH test only (McNemar's test, p=0.03). At follow up, 73.7 % (28/38), 52.6 % (20/38), 48.6 % (17/35), and 13.2 % (5/38) of study participants were HRP-2 positive on days 14, 28, 35 and 42, respectively, compared to 0, 2.6 % (1/38), 2.9 % (1/35), and 2.6 % (1/38) for LDH.

CONCLUSION

The HRP2 based RDT fulfilled WHO criteria for malaria diagnosis in SCD patients and may provide diagnostic evidence for treatment to begin in cases where treatment would otherwise have begun presumptively based on symptoms, while LDH based RDT may be more suitable as a confirmatory test in low-parasitaemic sub-groups, such as SCD patients.

Decreased parasite burden and altered host response in children with sickle cell anemia and severe anemia with malaria

Plasmodium falciparum malaria causes morbidity and mortality in African children with sickle cell anemia (SCA), but comparisons of host responses to P falciparum between children with SCA (homozygous sickle cell disease/hemoglobin SS [HbSS]) and normal hemoglobin genotype/hemoglobin AA (HbAA) are limited. We assessed parasite biomass and plasma markers of inflammation and endothelial activation in children with HbAA (n = 208) or HbSS (n = 22) who presented with severe anemia and P falciparum parasitemia to Mulago Hospital in Kampala, Uganda. Genotyping was performed at study completion. No child had known SCA at enrollment. Children with HbSS did not differ from children with HbAA in peripheral parasite density, but had significantly lower sequestered parasite biomass. Children with HbSS had greater leukocytosis but significantly lower concentrations of several plasma inflammatory cytokines, including tumor necrosis factor α (TNF-α). In contrast, children with HbSS had threefold greater concentrations of angiopoietin-2 (Angpt-2), a marker of endothelial dysregulation associated with mortality in severe malaria. Lower TNF-α concentrations were associated with increased risk of postdischarge mortality or readmission, whereas higher Angpt-2 concentrations were associated with increased risk of recurrent clinical malaria. Children with SCA have decreased parasite sequestration and inflammation but increased endothelial dysregulation during severe anemia with P falciparum parasitemia, which may ameliorate acute infectious complications but predispose to harmful long-term sequelae.

Analysis of clinical presentation, hematological factors, self-reported bed net usage, and malaria burden in sickle cell disease patients

BACKGROUND

Sickle cell anemia (SCA) is a severe monogenic disorder, caused by single nucleotide mutations in the hemoglobin (Hb) gene, that is prevalent in malaria endemic regions of the world. Sickle cell trait (SCT) individuals carry only one of the mutated alleles and were shown to be protected against malaria. However, defining the relative contribution of hematological, clinical, and environmental factors to the overall burden of malaria in individuals with hemoglobinopathies such as SCA has been challenging.

METHODS

We hypothesized that hematological differences, clinical presentations, and self-reported bed net usage among Plasmodium-infected and uninfected individuals may govern overall malaria burden in individuals with sickle cell disease (SCD). We conducted a cross-sectional study in Ghana from 2014 to 2019 and described clinical presentations, hematological characteristics, and bed net use based on a comprehensive questionnaire. Hematological characteristics were compared using a parametric or nonparametric ANOVA, pending if data passed D'Agostino & Pearson normality test. When comparing only two Hb genotypes hematological characteristics a Mann-Whitney U-test were used. Logistic regressions and Chi-squared tests were used to compare questionnaire responses between Hb genotypes. All statistical significance was set at p < 0.05.

FINDINGS

Multiple hematological parameters were significantly (p < 0.05) altered depending on sickle cell genotype and/or malaria status. When compared to other Hb genotypes, SCA individuals with or without malaria had significantly (p < 0.05) higher WBC and platelets counts and lower Hb levels. While the sickle cell genotype may affect malaria severity, SCT and SCA participants were found to significantly (p < 0.007) use bet nets more than HbAA participants.

INTERPRETATIONS

Our findings can be utilized to enhance national guidelines for reducing the incidence of malaria especially among individuals with SCD, SCT protection and health disparities among hemoglobinopathies.

FUNDING

This study was supported by the National Institute for Health.

Suspected Severe Malaria in a Sudanese Patient Affected by Sickle Cell Disease Who Was Treated with Hydroxyurea

Sickle cell disease (SCD) is the most common genetic disease in sub-Saharan Africa. The signs and symptoms of SCD usually begin in early childhood. Characteristic features of this disorder include anaemia, repeated infections, and periodic episodes of pain. Malaria is one of the infections that can occur in patients with SCD in endemic countries. Many guidelines recommend antimalarial chemoprophylaxis in these patients, although the debate on which drug should be used is still ongoing. Hydroxyurea (HU), which is considered a safe and effective treatment for both children and adults with SCD, seems to affect the incidence and severity of malaria, although these impacts have yet to be fully demonstrated. We report a case of an eight-and-a-half-year-old Sudanese boy with SCD treated with HU admitted for suspected severe malaria who showed a recrudescence after first-line treatment. Although he had undergone splenectomy and thus belonged to a category of patients at high risk for infectious complications, he was not receiving any malaria chemoprophylaxis. This case emphasises the importance of the routine administration of malaria prophylaxis to children with SCD living in endemic areas, even when they are treated with HU, and especially if they are at high risk for infectious complications because they have undergone splenectomy. There is an urgent need for further research to evaluate the most appropriate regimen and its optimal duration.

A cross-sectional study of the prevalence, density, and risk factors associated with malaria transmission in urban communities of Ibadan, Southwestern Nigeria

Background

Malaria is a severe global public health challenge that causes significant morbidity and mortality worldwide, particularly in sub-Saharan Africa. This study was designed to determine the prevalence, parasite density, and risk factors associated with malaria infection transmission among residents of two urban communities of Ibadan, southwestern Nigeria.

Materials and methods

A cross-sectional hospital-based study was carried out on 300 participants. Blood samples were obtained. Thick and thin blood films were prepared and viewed using the standard parasitological technique of microscopy. Moreover, data on sociodemographic and environmental variables were obtained using a pre-tested standard questionnaire.

Results

Of the 300 participants examined, a total of 165 (55.0%) were found positive for Plasmodium falciparum with a mean (S.D) parasite density of 1814.70 (1829.117) parasite/μL of blood. The prevalence and parasite density of malaria infection vary significantly (P < 0.05) with age group. Children <5 years old were more likely to have malaria infection and high parasite densities than adults (p < 0.05). Similarly, in relation to gender, males significantly (P < 0.05) had a higher prevalence (60.2%) and mean (S.D) parasite density of malaria infection [2157.73 (1659.570) parasite/μL of blood] compared to females. Additionally, those without formal education had the highest prevalence (73.0%) and mean (S.D) parasite density of infection [2626.96 (2442.195) parasite/μL of blood]. The bivariate logistic regression analysis shows that age group 6–10 (Crude Odds Ratio, COR 0.066, 95% CI: 0.007–0.635), presence of streams/rivers (COR 0.225, 95% CI: 0.103–0.492), distance from streams/rivers within ≤1 km (COR 0.283, 95% CI: 0.122–0.654) and travel to rural area (COR 4.689, 95% CI: 2.430–9.049) were the significant risk factors.

Conclusions

Malaria infection is prevalent in the study area and was greatly influenced by traveling activities from the rural areas to urban centers and vice versa. Multifaceted and integrated control strategy should be adopted. Health education on mosquito prevention and chemoprophylaxis before and during travel to rural areas are essential.

Association between haematological parameters and sickle cell genotypes in children with Plasmodium falciparum malaria resident in Kisumu County in Western Kenya

Background

Sickle cell disease (SCD) is a monogenic disorder due to point mutation in the β-globin gene resulting in substitution of Valine for Glutamic acid. The SCD is prevalent in P. falciparum endemic regions such as western Kenya. Carriage of different sickle cell genotypes may influence haematological parameter during malaria. Children resident in malaria holoendemic regions suffer more from malaria-related complications and this is moderated by the presence of the SCD. In the current study, we determined the association between sickle cell genotypes and haematological parameters in children with P. falciparum malaria resident in Kisumu County in Western Kenya.

Methodology

Children (n = 217, aged 1–192 months) with acute febrile condition were recruited at Jaramogi Oginga Odinga Teaching and Referral Hospital. Chi-square (χ2) analysis was used to determine differences between proportions. Differences in haematological parameters were compared across groups using Kruskal Wallis test and between groups using Mann Whitney U test. Multivariate logistic regression analysis controlling for infection status was used to determine the association between sickle cell genotypes and haematological parameters.

Results

Using HbAA as the reference group, multivariate logistic regression analysis revealed that carriage of HbSS was associated with reduced haemoglobin [OR = 0.310, 95% CI = 0.101–0.956, P = 0.041], reduced haematocrit [OR = 0.318, 95% CI = 0.128–0.793, P = 0.014], reduced RBC count [OR = 0.124, 95% CI = 0.045–0.337, P = 0.001], reduced MCHC [OR = 0.325, 95% CI = 0.118–0.892, P = 0.029], increased leucocytosis [OR = 9.283, 95% CI = 3.167–27.210, P = 0.001] and reduced monocytosis [OR = 0.319, 95% CI = 0.123–0.830, P = 0.019]. However, carriage of HbAS was only associated with increased micro-platelets [OR = 3.629, 95% CI = 1.291–8.276, P = 0.012].

Conclusion

Results show that carriage of HbSS in children influence the levels of haemoglobin, haematocrit, RBC, MCHC, WBC and Monocytes. Therefore prior knowledge of HbSS should be considered to improve clinical management of haematological alterations during malaria in children.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12879-020-05625-z.

Status of Anaemia and Malaria Co-infection With HIV From HAART Clinics in Federal Capital Territory, Nigeria: A Cross-Sectional Study

Background:

Malaria and HIV are 2 significant infections of critical public health concern globally. Malaria infection is one of the preceding causes of morbidity and mortality in endemic developing countries, and its co-infections in HIV patients worsen prognosis; with anaemia being the most common haematologic outcome of the infections.

Context and Purpose of Study:

This study was aimed at determining the prevalence of anaemia and malaria co-infection among HIV-infected patients attending selected hospitals in Abuja between February and July 2019.

Methods:

A cross-sectional study was carried out to detect malaria in 420 HIV-positive patients who were 12 to 67 years old, using enzyme immunoassay and microscopy. A structured questionnaire was used to capture socio-demographic and risk factors ([Frequency of] Use of Malaria preventive Measures, History of anaemia, Blood type, malaria antecedents, and CD4+ Count) while packed cell volume was checked using micro haematocrit reader to determine anaemia status. Data were analysed using IBM SPSS v25.

Results:

The mean age of the study participants was 37.5 (±12.48). A total of 142 (33.8%) samples were positive for malaria, and 68 of the HIV-infected patients (16.2%) were anaemic; 4.8% of the 420 patients had malaria co-infection and anaemia simultaneously. More male participants had malaria co-infection (36.0%, P = .617) while more female participants had anaemia (22.7%, P = .058). Patients aged 61 to 70 years had the highest rates of malaria and those aged 51 to 60 years were most anaemic. Except for patients with normal CD4+ count, those who were more exposed to the evaluated risk factors were more co-infected and anaemic. Malaria co-infection did not significantly affect the onset of anaemia. Test for the validity of Microscopy against Enzyme Immunoassay (EIA) showed 83.1% sensitivity and 98.6% specificity. No association was observed between the variables and the parasitaemia density of the patients.

Conclusions:

This study highlighted higher rates of malaria co-infection and anaemia among HIV patients when compared with previous reports in the region although co-infection did not significantly affect anaemia status. Given this trend, strategies must be put in place to checkmate these ailments. Population studies are also advocated.

Influence of blood group, Glucose-6-phosphate dehydrogenase and Haemoglobin genotype on Falciparum malaria in children in Vihiga highland of Western Kenya

Background

Genetic diversity of ABO blood, glucose-6-phosphate dehydrogenase (G6PD) deficiency and haemoglobin type and their ability to protect against malaria vary geographically, ethnically and racially. No study has been carried out in populations resident in malaria regions in western Kenya.

Method

A total of 574 malaria cases (severe malaria anaemia, SMA = 137 and non-SMA = 437) seeking treatment at Vihiga County and Referral Hospital in western Kenya, were enrolled and screened for ABO blood group, G6PD deficiency and haemoglobin genotyped in a hospital-based cross-sectional study.

Result

When compared to blood group O, blood groups A, AB and B were not associated with SMA (P = 0.380, P = 0.183 and P = 0.464, respectively). Further regression analysis revealed that the carriage of the intermediate status of G6PD was associated with risk to SMA (OR = 1.52, 95%CI = 1.029–2.266, P = 0.035). There was, however, no association between AS and SS with severe malaria anaemia. Co-occurrence of both haemoglobin type and G6PD i.e. the AA/intermediate was associated with risk to SMA (OR = 1.536, 95%CI = 1.007–2.343, P = 0.046) while the carriage of the AS/normal G6PD was associated with protection against SMA (OR = 0.337, 95%CI = 0.156–0.915, P = 0.031).

Conclusion

Results demonstrate that blood group genotypes do not have influence on malaria disease outcome in this region. Children in Vihiga with blood group O have some protection against malaria. However, the intermediate status of G6PD is associated with risk of SMA. Further, co-inheritance of sickle cell and G6PD status are important predictors of malaria disease outcome. This implies combinatorial gene function in influencing disease outcome.

Sickle cell disease and malaria: decreased exposure and asplenia can modulate the risk from Plasmodium falciparum

Background

Patients with sickle cell disease (SCD), an inherited haemoglobinopathy, have increased risk of malaria, at least in part due to impaired splenic function. Infection with Plasmodium falciparum in SCD patients can trigger painful vaso-occlusive crisis, increase the severity of anaemia, and contribute to early childhood mortality.

Case presentation

A 17 year-old Tanzanian male with known SCD was admitted to Muhimbili National Hospital, a tertiary referral centre in Dar-es-Salaam, following an attack of malaria. From 2004 to 2007 the patient had lived in USA, and from 2010 to 2016 in France where, on account of hypersplenism and episodes of splenic sequestrations, in 2014 the spleen was removed. After appropriate clinical and laboratory assessment the patient was re-started on hydroxyurea; and anti-malarial-prophylaxis with proguanil was instituted. The patient has remained well and malaria-free for the following 15 months.

Conclusion

SCD patients are highly vulnerable to malaria infection, and impaired splenic function is a feature of SCD patients, even in those who still anatomically have a spleen. This patient had a surgical splenectomy and, in addition, had probably lost some of the acquired malaria-immunity by having lived for several years in malaria-free areas. This patient is a compelling reminder that long-term anti-malarial prophylaxis should be offered to all patients with SCD who live in malaria-endemic areas.

Human genetics and malaria resistance

Malaria has been the pre-eminent cause of early mortality in many parts of the world throughout much of the last five thousand years and, as a result, it is the strongest force for selective pressure on the human genome yet described. Around one third of the variability in the risk of severe and complicated malaria is now explained by additive host genetic effects. Many individual variants have been identified that are associated with malaria protection, but the most important all relate to the structure or function of red blood cells. They include the classical polymorphisms that cause sickle cell trait, α-thalassaemia, G6PD deficiency, and the major red cell blood group variants. More recently however, with improving technology and experimental design, others have been identified that include the Dantu blood group variant, polymorphisms in the red cell membrane protein ATP2B4, and several variants related to the immune response. Characterising how these genes confer their effects could eventually inform novel therapeutic approaches to combat malaria. Nevertheless, all together, only a small proportion of the heritable component of malaria resistance can be explained by the variants described so far, underscoring its complex genetic architecture and the need for continued research.

Fever Management in Sickle Cell Disease in Low- and Middle-Income Countries: A Survey of SCD Management Programs

Management of fever is a key element of care for children with sickle cell disease (SCD). There exist few studies of current practices in managing fevers in SCD in low- and middle-income countries (LMICs) and malaria-endemic regions where SCD is prevalent. We surveyed medical providers in these settings to characterize current practices in infection prevention and fever management for children with SCD. We found wide variation in use of newborn screening for early diagnosis and infection prevention, pneumococcal vaccination, use of antibiotics and antimalarials, and route of antibiotic administration. Counter to established guidelines, 78% (95% CI: 59-100%) of respondents would consider using oral antibiotics for a febrile child with SCD. Only 17% (95% CI: 0-37%) would administer antibiotics to a well-appearing child with a positive malaria test. Availability of blood cultures did not affect duration of antibiotic course. Further study and standardization of fever management in SCD in LMICs are urgently needed.

Malaria in patients with sickle cell anaemia: burden, risk factors and outcome at the Laquintinie hospital, Cameroon

BACKGROUND

It is believed that the current prevalence of malaria in endemic areas reflects selection for the carrier form of sickle cell trait through a survival advantage. Malaria has been incriminated as a great cause of mortality in people with sickle cell disease (SCD). However, people with SCD, a high-risk group, do not benefit from free or subsisized malaria prevention and treatment in Cameroon unlike other vulnerable groups which may be due to insufficient evidence to guide policy makers. This study aimed at describing clinical and socio-demographic characteristics of patients with malaria, determining the prevalence of malaria in hospitalized children and in those with SCD and without, compare frequency of presentation of malaria related complications (using clinical and laboratory elements that define severe malaria) between children admitted for malaria with SCD and those without and finally, determing the risk factors for death in children admitted for malaria.

METHODS

This was a retrospective analysis of admission records of children age 1 to 18 years with a confirmed malaria diagnosis admitted at the Laquintinie Hospital during January 2015 through December 2018. Clinical features, laboratory characteristics and outcome of malarial infections, stratified by SCD status were studied. Patients with HIV infection, malnutrition, renal failure and discharged against medical advice were excluded from the study. Data were analysed using Epi-info 7 software and analysis done. Chi square test, Odds ratios, CI and student's t test were used to determine association between variables. Statistical significance was set at p-value ≤0.05.

RESULTS

The prevalence of malaria was lower among children with SCD than it was among children without SCD (23.5% vs 44.9%). Similarly, among those with a positive microscopy, the mean parasite density was significantly lower among children with SCD than it was among children without SCD (22,875.6 vs 57,053.6 parasites/ μl with t-value - 3.2, p-value 0.002). The mean hemoglobin concentration was lower in SCD as compared to non SCD (5.7 g/l vs 7.4 g/l, t-value - 12.5, p-value < 0.001). Overall mortality in SCD was 3.4% and malaria was reponsible for 20.4% of these deaths as compared to the 35.4% in non SCD patients. Convulsion and impaired consciousness were significantly lower in SCD group (OR:0.1, CI: 0.1-0.3, p value < 0.01 and OR:0.1, CI:0.1-0.2, p-value < 0.001 respectively). Death was significantly higher in SCD patients with malaria as compared to SCD patients admitted for other pathologies (3.2% vs 1.5%., OR:2.2, CI:1-5, p-value 0.050).

CONCLUSION

The SCD population has a lower mortality related to malaria compared to the non-SCD population. Meanwhile, within the SCD population, those admitted with malaria are twice more likely to die than those admitted for other pathologies. Jaundice, hepatomegaly and splenomegaly were common in SCD with malaria, however no risk factors for malaria severity or malaria related death was identified.

Life-Threatening Infectious Complications in Sickle Cell Disease: A Concise Narrative Review

Sickle cell disease (SCD) results in chronic hemolytic anemia, recurrent vascular occlusion, insidious vital organ deterioration, early mortality, and diminished quality of life. Life-threatening acute physiologic crises may occur on a background of progressive diminishing vital organ function. Sickle hemoglobin polymerizes in the deoxygenated state, resulting in erythrocyte membrane deformation, vascular occlusion, and hemolysis. Vascular occlusion and increased blood viscosity results in functional asplenia and immune deficiency in early childhood, resulting in life-long increased susceptibility to serious bacterial infections. Infection remains a main cause of overall mortality in patients with SCD in low- and middle-income countries due to increased exposure to pathogens, increased co-morbidities such as malnutrition, lower vaccination rates, and diminished access to definitive care, including antibiotics and blood. Thus, the greatest gains in preventing infection-associated mortality can be achieved by addressing these factors for SCD patients in austere environments. In contrast, in high-income countries, perinatal diagnosis of SCD, antimicrobial prophylaxis, vaccination, aggressive use of antibiotics for febrile episodes, and the availability of contemporary critical care resources have resulted in a significant reduction in deaths from infection; however, chronic organ injury is problematic. All clinicians, regardless of their discipline, who assume the care of SCD patients must understand the importance of infectious disease as a contributor to death and disability. In this concise narrative review, we summarize the data that describes the importance of infectious diseases as a contributor to death and disability in SCD and discuss pathophysiology, prevalent organisms, prevention, management of acute episodes of critical illness, and ongoing care.

Comparison between Adult Patients with Sickle Cell Disease of Sub-Saharan African Origin Born in Metropolitan France and in Sub-Saharan Africa

Sickle cell disease (SCD) prevalence has increased rapidly in Europe as a result of an increase in the life expectancy of these patients and the arrival of SCD migrants from Africa. The aim of our study was to compare the phenotypes of adult patients born in Sub-Saharan Africa (SSA) who migrated to France with those of patients with the same origin who were born in France. This single-center observational study compared the demographic, clinical and biological characteristics of SCD adult patients of SSA origin who were born in France or SSA. Data were collected from computerized medical charts. Groups were compared using multivariate logistic regression with adjustment for age, gender and type of SCD. Of the 323 SCD patients followed in our center, 235 were enrolled, including 111 patients born in France and 124 patients born in SSA. SCD genotypes were balanced between groups. Patients born in Africa were older (median age 32.1 (24.4-39) vs. 25.6 (22.1-30.5) years, p < 0.001) and more often women (n = 75 (60.5%) vs. 48 (43.2%), p = 0.008). The median age at arrival in France was 18 years (13-23). The median height was lower among patients born in SSA (169 (163-175) vs. 174.5 cm (168-179), p < 0.001). Over their lifetimes, patients born in France had more acute chest syndromes (median number 2 (1-4) vs. 1 (0-3), p = 0.002), with the first episode occurring earlier (19 (11.6-22.3) vs. 24 (18.4-29.5) years, p < 0.007), and were admitted to intensive care units more often (53.3% vs. 34.9%, p = 0.006). This difference was more pronounced in the SS/Sβ0 population. Conversely, patients born in SSA had more skin ulcers (19.4% vs. 6.3%, p = 0.03). No significant differences were found in social and occupational insertion or other complications between the two groups. Patients born in SSA had a less severe disease phenotype regardless of their age than those born in France. This difference could be related to a survival bias occurring in Africa during childhood and migration to Europe that selected the least severe phenotypes.

Sickle Cell Disease and Infections in High- and Low-Income Countries

Infections, especially pneumococcal septicemia, meningitis, and Salmonella osteomyelitis, are a major cause of morbidity and mortality in patients with sickle cell disease (SCD). SCD increased susceptibility to infection, while infection leads to SCD-specific pathophysiological changes. The risk of infectious complications is highest in children with a palpable spleen before six months of age. Functional splenectomy, the results of repeated splenic infarctions, appears to be a severe host-defense defect. Infection is the leading cause of death, particularly in less developed countries. Defective host-defense mechanisms enhance the risk of pneumococcal complications. Susceptibility to Salmonella infections can be explained at least in part by a similar mechanism. In high-income countries, the efficacy of the pneumococcal vaccine has been demonstrated in this disease. A decreased in infection incidence has been noted in SCD patients treated prophylactically with daily oral penicillin. Studies in low-income countries suggest the involvement of a different spectrum of etiological agents.

Sickle cell disease: Reducing the global disease burden

Sickle cell disease has been largely an invisible global health issue, especially in regions of high incidence mainly due to lack of awareness among both the local health policy makers and the public. Public health interventions, such as screening of newborns, provision of prophylaxis against bacterial infections, and immunizations against pneumococcal infections can have the greatest impact. Family education on assessment of spleen size and subsequent detection of splenic sequestration and promptness to seek medical attention for a febrile child is also important in the control of the morbidity and mortality of children with SCD living in resource-poor countries. In addition to these affordable interventions, hydroxyurea therapy is necessary to decrease both the acute and chronic complications of sickle cell anemia. Sickle cell disease has been recognized to have global health significance by key institutions including the World Health Organization in 2006 and the United Nation is 2008. In 2010, the WHO released national health care management goals and set targets to be achieved by the countries in sub-Saharan Africa for the control and management of SCD. These are yet to be translated into action. To do, this would require active and sustainable public-private partnerships for sustainable program development in these regions. Effective interventions should be integrated into existing health systems, the best examples linking primary healthcare facilities to specialized sickle cell disease centers in regional and tertiary healthcare institutions.

Population Pharmacokinetic Estimates Suggest Elevated Clearance and Distribution Volume of Desethylamodiaquine in Pediatric Patients with Sickle Cell Disease Treated with Artesunate-Amodiaquine

Background

There is limited information on the safety or efficacy of currently recommended antimalarial drugs in patients with sickle cell disease (SCD), a population predisposed to worse outcomes if affected by acute malaria. Artesunate-amodiaquine (ASAQ) is the first-line treatment for uncomplicated malaria (UM) in many malaria-endemic countries and is also used for treatment of UM in SCD patients. There is, however, no information to date, on the pharmacokinetics (PK) of amodiaquine or artesunate or the metabolites of these drugs in SCD patients.

Objectives

This study sought to determine the PK of desethylamodiaquine (DEAQ), the main active metabolite of amodiaquine, among paediatric SCD patients with UM treated with artesunate-amodiaquine (ASAQ).

Methods

Plasma concentration-time data (median DEAQ levels) of SCD children (n = 16) was initially compared with those of concurrently recruited non-SCD paediatric patients with acute UM (n = 13). A population PK modelling approach was then used to analyze plasma DEAQ concentrations obtained between 64 and 169 hours after oral administration of ASAQ in paediatric SCD patients with acute UM (n = 16). To improve PK modeling, DEAQ concentration-time data (n = 21) from SCD was merged with DEAQ concentration-time data (n = 169) of a historical paediatric population treated with ASAQ (n = 103) from the same study setting.

Results

The median DEAQ concentrations on days 3 and 7 were comparatively lower in the SCD patients compared to the non-SCD patients. A two-compartment model best described the plasma DEAQ concentration-time data of the merged data (current SCD data and historical data). The estimated population clearance of DEAQ was higher in the SCD patients (67 L/h, 21% relative standard error (RSE) compared with the non-SCD population (15.5 L/h, 32% RSE). The central volume of distribution was larger in the SCD patients compared with the non-SCD patients (4400 L, 43% RSE vs. 368 L, 34% RSE).

Conclusions

The data shows a tendency towards lower DEAQ concentration in SCD patients and the exploratory population PK estimates suggest altered DEAQ disposition in SCD patients with acute UM. These findings, which if confirmed, may reflect pathophysiological changes associated with SCD on DEAQ disposition, have implications for therapeutic response to amodiaquine in SCD patients. The limited number of recruited SCD patients and sparse sampling approach however, limits extrapolation of the data, and calls for further studies in a larger population.

Hydroxyurea for Children with Sickle Cell Anemia in Sub-Saharan Africa

BACKGROUND

Hydroxyurea is an effective treatment for sickle cell anemia, but few studies have been conducted in sub-Saharan Africa, where the burden is greatest. Coexisting conditions such as malnutrition and malaria may affect the feasibility, safety, and benefits of hydroxyurea in low-resource settings.

METHODS

We enrolled children 1 to 10 years of age with sickle cell anemia in four sub-Saharan countries. Children received hydroxyurea at a dose of 15 to 20 mg per kilogram of body weight per day for 6 months, followed by dose escalation. The end points assessed feasibility (enrollment, retention, and adherence), safety (dose levels, toxic effects, and malaria), and benefits (laboratory variables, sickle cell-related events, transfusions, and survival).

RESULTS

A total of 635 children were fully enrolled; 606 children completed screening and began receiving hydroxyurea at a mean (±SD) dose of 17.5±1.8 mg per kilogram per day. The retention rate was 94.2% at 3 years of treatment. Hydroxyurea therapy led to significant increases in both the hemoglobin and fetal hemoglobin levels. Dose-limiting toxic events regarding laboratory variables occurred in 5.1% of the participants, which was below the protocol-specified threshold for safety. During the treatment phase, 20.6 dose-limiting toxic effects per 100 patient-years occurred, as compared with 20.7 events per 100 patient-years before treatment. As compared with the pretreatment period, the rates of clinical adverse events decreased with hydroxyurea use, including rates of vaso-occlusive pain (98.3 vs. 44.6 events per 100 patient-years; incidence rate ratio, 0.45; 95% confidence interval [CI], 0.37 to 0.56), nonmalaria infection (142.5 vs. 90.0 events per 100 patient-years; incidence rate ratio, 0.62; 95% CI, 0.53 to 0.72), malaria (46.9 vs. 22.9 events per 100 patient-years; incidence rate ratio, 0.49; 95% CI, 0.37 to 0.66), transfusion (43.3 vs. 14.2 events per 100 patient-years; incidence rate ratio, 0.33; 95% CI, 0.23 to 0.47), and death (3.6 vs. 1.1 deaths per 100 patient-years; incidence rate ratio, 0.30; 95% CI, 0.10 to 0.88).

CONCLUSIONS

Hydroxyurea treatment was feasible and safe in children with sickle cell anemia living in sub-Saharan Africa. Hydroxyurea use reduced the incidence of vaso-occlusive events, infections, malaria, transfusions, and death, which supports the need for wider access to treatment. (Funded by the National Heart, Lung, and Blood Institute and others; REACH ClinicalTrials.gov number, NCT01966731 .).

Safety and effectiveness of antimalarial therapy in sickle cell disease: a systematic review and network meta-analysis

BACKGROUND

About 80% of all reported sickle cell disease (SCD) cases in children anually are recorded in Africa. Although malaria is considered a major cause of death in SCD children, there is limited data on the safety and effectiveness of the available antimalarial drugs used for prophylaxis. Also, previous systematic reviews have not provided quantitative measures of preventive effectiveness. The purpose of this research was to conduct a systematic review and meta-analysis of the available literature to determine the safety and effectiveness of antimalarial chemoprophylaxis used in SCD patients.

METHODS

We searched in PubMed, Medline, CINAHL, POPLine and Cochrane library, for the period spanning January 1990 to April 2018. We considered randomized or quasi-randomized controlled trials comparing any antimalarial chemoprophylaxis to, 1) other antimalarial chemoprophylaxis, 2) placebo or 3) no intervention, in SCD patients. Studies comparing at least two treatment arms, for a minimum duration of three months, with no restriction on the number of patients per arm were reviewed. The data were extracted and expressed as odds ratios. Direct pairwise comparisons were performed using fixed effect models and the heterogeneity assessed using the I-square.

RESULTS

Six qualified studies that highlighted the importance of antimalarial chemoprophylaxis in SCD children were identified. In total, seven different interventions (Chloroquine, Mefloquine, Mefloquine artesunate, Proguanil, Pyrimethamine, Sulfadoxine-pyrimethamine, Sulfadoxine-pyrimethamine amodiaquine) were evaluated in 912 children with SCD. Overall, the meta-analysis showed that antimalarial chemoprophylaxis provided protection against parasitemia and clinical malaria episodes in children with SCD. Nevertheless, the risk of hospitalization (OR = 0.72, 95% CI = 0.267-1.959; I2 = 0.0%), blood transfusion (OR = 0.83, 95% CI = 0.542-1.280; I2 = 29.733%), vaso-occlusive crisis (OR = 19, 95% CI = 1.713-2.792; I2 = 93.637%), and mortality (OR = 0.511, 95% CI = 0.189-1.384; I2 = 0.0%) did not differ between the intervention and placebo groups.

CONCLUSION

The data shows that antimalarial prophylaxis reduces the incidence of clinical malaria in children with SCD. However, there was no difference between the occurrence of adverse events in children who received placebo and those who received prophylaxis. This creates an urgent need to assess the efficacy of new antimalarial drug regimens as potential prophylactic agents in SCD patients.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO (CRD42016052514).

Resistance to Plasmodium falciparum in sickle cell trait erythrocytes is driven by oxygen-dependent growth inhibition

Sickle cell trait (AS) confers partial protection against lethal Plasmodium falciparum malaria. Multiple mechanisms for this have been proposed, with a recent focus on aberrant cytoadherence of parasite-infected red blood cells (RBCs). Here we investigate the mechanistic basis of AS protection through detailed temporal mapping. We find that parasites in AS RBCs maintained at low oxygen concentrations stall at a specific stage in the middle of intracellular growth before DNA replication. We demonstrate that polymerization of sickle hemoglobin (HbS) is responsible for this growth arrest of intraerythrocytic P. falciparum parasites, with normal hemoglobin digestion and growth restored in the presence of carbon monoxide, a gaseous antisickling agent. Modeling of growth inhibition and sequestration revealed that HbS polymerization-induced growth inhibition following cytoadherence is the critical driver of the reduced parasite densities observed in malaria infections of individuals with AS. We conclude that the protective effect of AS derives largely from effective sequestration of infected RBCs into the hypoxic microcirculation.

Sickle cell disease

Sickle cell disease (SCD) is a group of inherited disorders caused by mutations in HBB, which encodes haemoglobin subunit β. The incidence is estimated to be between 300,000 and 400,000 neonates globally each year, the majority in sub-Saharan Africa. Haemoglobin molecules that include mutant sickle β-globin subunits can polymerize; erythrocytes that contain mostly haemoglobin polymers assume a sickled form and are prone to haemolysis. Other pathophysiological mechanisms that contribute to the SCD phenotype are vaso-occlusion and activation of the immune system. SCD is characterized by a remarkable phenotypic complexity. Common acute complications are acute pain events, acute chest syndrome and stroke; chronic complications (including chronic kidney disease) can damage all organs. Hydroxycarbamide, blood transfusions and haematopoietic stem cell transplantation can reduce the severity of the disease. Early diagnosis is crucial to improve survival, and universal newborn screening programmes have been implemented in some countries but are challenging in low-income, high-burden settings.

The clinical epidemiology of sickle cell anemia In Africa

Sickle cell anemia (SCA) is the commonest severe monogenic disorders of humans. The disease has been highly characterized in high‐income countries but not in sub‐Saharan Africa where SCA is most prevalent. We conducted a retrospective cohort study of all children 0–13 years admitted from within a defined study area to Kilifi County Hospital in Kenya over a five‐year period. Children were genotyped for SCA retrospectively and incidence rates calculated with reference to population data. Overall, 576 of 18,873 (3.1%) admissions had SCA of whom the majority (399; 69.3%) were previously undiagnosed. The incidence of all‐cause hospital admission was 57.2/100 person years of observation (PYO; 95%CI 52.6–62.1) in children with SCA and 3.7/100 PYO (95%CI 3.7–3.8) in those without SCA (IRR 15.3; 95%CI 14.1–16.6). Rates were higher for the majority of syndromic diagnoses at all ages beyond the neonatal period, being especially high for severe anemia (hemoglobin <50 g/L; IRR 58.8; 95%CI 50.3–68.7), stroke (IRR 486; 95%CI 68.4–3,450), bacteremia (IRR 23.4; 95%CI 17.4–31.4), and for bone (IRR 607; 95%CI 284–1,300), and joint (IRR 80.9; 95%CI 18.1–362) infections. The use of an algorithm based on just five clinical features would have identified approximately half of all SCA cases among hospital‐admitted children with a number needed to test to identify each affected patient of only fourteen. Our study illustrates the clinical epidemiology of SCA in a malaria‐endemic environment without specific interventions. The targeted testing of hospital‐admitted children using the Kilifi Algorithm provides a pragmatic approach to early diagnosis in high‐prevalence countries where newborn screening is unavailable.

Possible Risk Factors for Severe Anemia in Hospitalized Sickle Cell Patients at Muhimbili National Hospital, Tanzania: Protocol for a Cross-Sectional Study

Background

Sickle cell disease (SCD) is the most common inherited disorder worldwide, with the highest burden in sub-Saharan Africa. The natural history of SCD is characterized by periods of steady state interspersed by acute episodes. The acute anemic crises may be transient and are precipitated by treatable factors like infections, nutritional deficiencies, and sequestration. Anemia is almost always present, although it occurs at different levels of severity.

Objective

This paper describes the protocol of a cross-sectional study to determine the prevalence of severe anemia and associated factors among sickle cell patients hospitalized at the Muhimbili National Hospital.

Methods

This is an ongoing, descriptive, cross-sectional, hospital-based study among individuals with SCD, admitted to the Muhimbili National Hospital in Dares Salaam, Tanzania. A minimum sample size of 369 was calculated based on the previous prevalence of hospitalizations due to severe anemia (20%) in the same cohort. We are using a piloted standardized case report form to document clinical and laboratory parameters following informed consent. Data analysis will be performed using Stata software. Severe anemia is defined as Hb<5g/dL. Chi-square or Fisher’s exact test will be used to ascertain association between categorical variables, and t-test will be used for numerical variables. Regression models for severe anemia against explanatory and confounding variables will be run, and results will be presented as adjusted odds ratio with 95% confidence intervals. A P value of <.05 will be considered significant.

Results

Enrolment commenced in January 2015 and concluded in September 2016. Complete data analysis will begin in February 2018. The study results are expected to be published in May 2018.

Conclusions

This protocol paper will provide a useful and practical model for conducting cross-sectional studies in hospitalized patients that cover a wide ranging of clinical and laboratory variables.

Factors Influencing the Academic Performance of Children with Sickle Cell Anaemia in Ekiti, South West Nigeria

BACKGROUND

There is a paucity of information on factors that influence the school performance of children with sickle cell anaemia (SCA) in Nigeria, despite her huge burden of the disease.

METHODS

In total, 101 children with SCA were recruited at a paediatric clinic in Nigeria. Their socio-demographic-matched classmates were the controls. Academic performance and cognitive functioning were obtained from school reports and Ziler's Draw-a-Person Test, respectively. Factors influencing the academic performance were determined.

RESULTS

Children with SCA had higher rates of school absence and lower haemoglobin concentration (p < 0.05). There was no difference in overall school performance between children with SCA and controls (59.0 vs. 60.6%; p = 0.256). School absenteeism > 1 week independently predicts poor school performance among the study participants (odds ratio = 15.71; 95% confidence interval = 5.93-41.66; p =0.000). Most SCA children with poor performance were absent from school for > 1 week.

CONCLUSION

There is need to address causes of school absenteeism among children with SCA.

Diagnostic challenges of prolonged post-treatment clearance of Plasmodium nucleic acids in a pre-transplant autosplenectomized patient with sickle cell disease

BACKGROUND

Autosplenectomy, as a result of sickle cell disease, is an important risk factor for severe malaria. While molecular methods are helpful in providing rapid and accurate infection detection and species identification, the effect of hyposplenism on result interpretation during the course of infection should be carefully considered.

CASE PRESENTATION

A 32-year old autosplenectomized Nigerian male with severe sickle cell disease was referred to the National Institutes of Health for allogenic hematopoietic stem cell transplant. Despite testing negative for malaria by both smear and PCR 2 weeks after arrival in the USA, the patient developed fever and diffuse bilateral lower rib cage and upper abdominal pain 2 weeks later and subsequently tested positive for Plasmodium falciparum. Parasitaemia was tracked over time by microscopy and nucleic acid tests to evaluate the therapeutic response in the setting of hyposplenism. The patient showed prompt resolution of patent infection by microscopy but remained positive by molecular methods for > 30 days after treatment initiation.

CONCLUSION

While molecular testing can provide sensitive Plasmodium nucleic acid detection, the persistence of Plasmodium nucleic acids following adequate treatment in functionally asplenic patients can lead to a diagnostic dilemma. In such patients, clinical response and peripheral blood smears should guide patient management following treatment. Nonetheless, in pre-transplant patients at high-risk for pre-existing Plasmodium infections, highly sensitive molecular assays can be useful to rule out infection prior to transplantation.

Lack of mortality in 22 children with sickle cell anemia and severe malarial anemia

Retrospective studies suggest that there is high mortality in children with sickle cell anemia (SCA) and severe malaria. We assessed mortality in Ugandan children with severe malarial anemia (SMA, n = 232) or cerebral malaria (CM, n = 267) by sickle cell hemoglobin genotype. Admission and 2-year follow-up mortality did not differ among children with SMA who had homozygous form of sickle cell hemoglobin (HbSS) versus normal form of adult hemoglobin (admission, 0/22, 0%, vs. 1/208, 0.5%; follow-up, 1/22, 4.5%; 7/207, 3.4%, respectively; all P > 0.6). The single child with CM and HbSS survived. The study findings highlight the need for large prospective studies of malaria-related mortality in children with SCA.

Prescription audit in a paediatric sickle cell clinic in South-West Nigeria: A cross-sectional retrospective study

Background

Sickle cell disease (SCD) is a genetic haematological disorder that affects millions of people around the world especially people of African heritage. The treatment of the symptoms of SCD includes the use of analgesics, antibiotics, and anti-malarial drugs. Studying the pattern of drug prescription is a veritable tool for establishing the current practice and how it conforms to existing guidelines.

Objectives

The main objective of this study was to assess the pattern of drug prescription in children with sickle cell disease (SCD) attending the paediatric outpatients' clinic of a tertiary care centre in Ado-Ekiti, South-West Nigeria.

Methods

This was a cross-sectional retrospective study carried out using the medical records of all patients with SCD who attended the paediatric outpatient clinic of the teaching hospital between January 1 and December 31, 2014. The information retrieved from the case notes included the bio-demographic data, associated co-morbid conditions and the list of prescribed drugs.

Results

A total of 202 SCD patients aged below 18 years were seen in the clinic during the study period with males accounting for 61.9% of them. The mean age of all patients was 6.9 ±3.8 yrs. A total of 1015 medications were prescribed during the study period giving a mean of 5.02 ± 1.9. Vitamins/micronutrients, anti-malarial drugs, antibiotics and analgesics accounted for 41.4%, 29.0%, 15.7% and 13.9% of all prescribed drugs respectively. Antibiotics from the penicillin group were the most commonly prescribed followed by macrolides and cephalosporins while Ibuprofen (60.3%) and Acetaminophen (32.6%) were the commonly prescribed analgesics.

Conclusion

High rate of antibiotic prescription, low use of opioid analgesics and non-prescription of prophylactic penicillin/pneumococcal vaccination were the main findings in this study. There is need for the introduction of standard treatment protocols for this group of patients.

Beta-globin gene haplotypes and selected Malaria-associated variants among black Southern African populations

Partial carrier-resistance to Plasmodium falciparum malaria conferred by the sickle cell (HbS) mutation has resulted in the local amplification and positive selection of sickle cell disease (SCD) in malaria-endemic regions and particularly in sub-Saharan Africa (SSA). The present study investigated the β-globin gene haplotypes, and selected malaria-associated variants among three cohorts of Bantu-speaking individuals from Malawi, Zimbabwe and South Africa compared with reports with data from others SSA populations. The data suggest a south-ward frequency decrease of malaria-associated variants in SSA linked to the evolutionary dynamics of various African populations’ genomes through selective pressure of malaria. These selected genomics differences, positive selection of SCD in malaria-endemic regions among ‘Bantus’ from various part of Africa emphasise the evidence of the dissociation between genetics, anthropology and culture. The present study also showed a relatively prevalent Benin haplotype, which is mostly found in West Africa, among Southern African Blacks and very low Bantu haplotype, which could suggest a major migration route, of Southern Africa Bantu, along the African west coast, post-occurrence of the Sickle cell mutation, which date remain to be fully elucidated.

Novel use Of Hydroxyurea in an African Region with Malaria (NOHARM): a trial for children with sickle cell anemia

Hydroxyurea treatment is recommended for children with sickle cell anemia (SCA) living in high-resource malaria-free regions, but its safety and efficacy in malaria-endemic sub-Saharan Africa, where the greatest sickle-cell burden exists, remain unknown. In vitro studies suggest hydroxyurea could increase malaria severity, and hydroxyurea-associated neutropenia could worsen infections. NOHARM (Novel use Of Hydroxyurea in an African Region with Malaria) was a randomized, double-blinded, placebo-controlled trial conducted in malaria-endemic Uganda, comparing hydroxyurea to placebo at 20 ± 2.5 mg/kg per day for 12 months. The primary outcome was incidence of clinical malaria. Secondary outcomes included SCA-related adverse events (AEs), clinical and laboratory effects, and hematological toxicities. Children received either hydroxyurea (N = 104) or placebo (N = 103). Malaria incidence did not differ between children on hydroxyurea (0.05 episodes per child per year; 95% confidence interval [0.02, 0.13]) vs placebo (0.07 episodes per child per year [0.03, 0.16]); the hydroxyurea/placebo malaria incidence rate ratio was 0.7 ([0.2, 2.7]; P = .61). Time to infection also did not differ significantly between treatment arms. A composite SCA-related clinical outcome (vaso-occlusive painful crisis, dactylitis, acute chest syndrome, splenic sequestration, or blood transfusion) was less frequent with hydroxyurea (45%) than placebo (69%; P = .001). Children receiving hydroxyurea had significantly increased hemoglobin concentration and fetal hemoglobin, with decreased leukocytes and reticulocytes. Serious AEs, sepsis episodes, and dose-limiting toxicities were similar between treatment arms. Three deaths occurred (2 hydroxyurea, 1 placebo, and none from malaria). Hydroxyurea treatment appears safe for children with SCA living in malaria-endemic sub-Saharan Africa, without increased severe malaria, infections, or AEs. Hydroxyurea provides SCA-related laboratory and clinical efficacy, but optimal dosing and monitoring regimens for Africa remain undefined. This trial was registered at www.clinicaltrials.gov as #NCT01976416.