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

Blood count changes in malaria patients according to blood groups (ABO/Rh) and sickle cell trait

INTRODUCTION

Introduction: Malaria continues to be the leading cause of hospitalization and death in Angola, a country in sub- Saharan Africa. In 2023, in the first quarter, 2,744,682 cases were registered, and of these 2,673 patients died due to malaria disease. Previous studies have shown that the ABO blood group can affect the progression of malaria to severe conditions after P. falciparum infection, while the sickle cell gene offers relative protection.

OBJECTIVE

We investigated changes in the blood count according to blood groups (ABO/Rh) and sickle cell trait in patients with malaria in Luanda, capital of Angola.

METHODOLOGY

This was a longitudinal, prospective and observational study with 198 patients hospitalized for malaria.

RESULTS

Of the 198 patients studied, 13(6.6%) were ABRh(+), 4(2.0%) were ARh(-), 49(24.7%) were ARh(+), 42(21, 2%) were BRh (+), 5(2.5%) were ORh(-) and 85(42.9%) were ORh(+). For sickle cell trait, 145(73.2%) were AA, 37(18.7%) were AS and 16(8.1%) were SS. No statistical relationship was observed between age group, sex, parasitemia, clinical picture, hematocrit, MCV, HCM, MCHC, leukocytes, NEUT, LINF and PTL values with blood groups (p<0.05), but there was a relationship between values of hemoglobin and ABO/Rh blood groups (p>0.05). There was no relationship between age, parasitemia, clinical condition, MCV, HCM and MCHC values, leukocytes, NEUT and LINF with sickle cell trait (p<0.05), but there was a relationship between sex, hemoglobin and PTL and sickle cell values. sickle cell trait (p>0.05).

CONCLUSION

It is imperative to differentiate patients with malaria based on blood groups and sickle cell trait, taking into account mainly the blood count parameters that demonstrate that there are patients who, depending on blood group or sickle cell trait, may react weakly to malaria infection regardless of the degree of parasitemia and medical prognosis.

Medical educators' perception of race in clinical practice

BACKGROUND

While several medical societies endorse race as a social construct, it is still often used as a biological trait in medical education. How medical educators employ race while teaching is likely impacted by their beliefs as to what race represents and its relevance in clinical care. Understanding these beliefs is necessary to guide medical education curriculum reform.

METHODS

This was a qualitative survey study, conducted in June 2020, of Georgetown University Medical Center faculty. As part of the survey, faculty were asked to rate, on a 5-point Likert scale, the extent to which they perceived race as a biological trait and its importance in clinical care. Self-identified clinical or preclinical faculty (N = 147) who believed that race had any importance were asked to provide an example illustrating its significance. Free-text responses were coded using content analysis with an inductive approach and contextualized by faculty's perspectives on the biological significance of race.

RESULTS

There were 130 (88%) responses categorized into two major themes: race is important for [1] screening, diagnosing, and treating diseases and [2] contextualizing patients' experiences and health behaviors. Compared to faculty who perceived race as biological, those who viewed race as strictly social were more likely to report using race to understand or acknowledge patients' exposure to racism. However, even among these faculty, explanations that suggested biological differences between racial groups were prevalent.

CONCLUSIONS

Medical educators use race primarily to understand diseases and frequently described biological differences between racial groups. Efforts to reframe race as sociopolitical may require education that examines race through a global lens, accounting for the genetic and cultural variability that occurs within racial groups; greater awareness of the association between structural racism and health inequities; movement away from identity-based risk stratification; and incorporation of tools that appraise race-based medical literature.

Comparison of in-hospital mortality in children and adolescents with sickle cell disease in a resource-limited setting before and during the COVID-19 pandemic

BACKGROUND

COVID-19 in children and adolescents with sickle cell disease (SCD) has variable presentations (from mild to severe disease), and the main symptoms are vaso-occlusive crises (VOC) and acute chest syndrome (ACS). We hypothesized that the desertion of hospitals due to the pandemic would lead to late arrival at the emergency room and an increased mortality. In this study, we sought to measure and compare the mortality of children with sickle cell disease before and during the COVID-19 pandemic.

MATERIAL AND METHODS

We conducted a retrospective cohort study at the sickle cell disease management center of Laquintinie Hospital in Douala (Cameroon). The study period was divided into two, i.e., from March 2019 to February 2020 (Pre-COVID-19) and from March 2020 to February 2021 (COVID-19). All administrative and ethical considerations were fully respected. Data were analyzed using SPSS 20.0.

RESULTS

Overall, 823 patients were admitted during the study period. Males represented 52.4% of the overall population, giving a sex ratio of 1.1:1. We admitted 479 patients during the pre-COVID-19 period versus 344 patients during the COVID-19 period, which is a 28.2% drop in admissions during the COVID-19 period. The mortality rate was 3.5% during the pre-COVID-19 period and 3.2% during the COVID-19 period (p>0.05). The most common causes of death were ACS (39.3%, n = 11), severe anemia (25.0%, n = 7), and VOC (17.9%, n = 5). ACS (adjusted odds ratio [aOR]=3.628, 95% confidence interval [CI], [1.645-7.005], p<0.001) was significantly associated with mortality.

CONCLUSION

During the COVID-19 pandemic, although the consultation frequency decreased, the mortality rate of sickle cell disease patients remained unchanged.

F-erythrocytes promote Plasmodium falciparum proliferation in sickle cell disease

BACKGROUND

Sickle cell disease (SCD) remains prevalent because heterozygous carriers (HbAS) are partially resistant to Plasmodium falciparum malaria. Sickle hemoglobin (HbS) polymerization in low and intermediate oxygen (O2 ) conditions is the main driver of HbAS-driven resistance to P. falciparum malaria. However, epidemiological studies have reported mixed malaria morbidity and mortality outcomes in individuals with sickle cell disease (SCD). While maximum-tolerated dose hydroxyurea has been shown to lower malaria incidence, fetal hemoglobin (HbF), an inhibitor of HbS polymerization that is variably packaged in F-erythrocytes, might provide hemoglobin that is accessible to the parasite for feeding.

METHODS

To explore that risk, we examined the effect of variable mean corpuscular fetal hemoglobin (MCHF) on P. falciparum proliferation, invasion, and development in HbSS RBCs.

RESULTS

We found that greater MCHF in HbSS red blood cells (RBCs) is associated with increased P. falciparum proliferation in O2 environments comparable with the microcirculation. Moreover, both parasite invasion and intracellular growth, the major components of proliferation, occur predominantly in F-erythrocytes and are augmented with increasing MCHF.

CONCLUSIONS

HbF modifies P. falciparum infection in HbSS RBCs, further highlighting the complexity of the molecular interactions between these two diseases. Other inhibitors of HbS polymerization that do not increase HbF or F-erythrocytes should be independently assessed for their effects on P. falciparum malaria proliferation in HbSS RBCs.

Fast detection and quantification of Plasmodium species infected erythrocytes in a non-endemic region by using the Sysmex XN-31 analyzer

Background

Due to increased travel from endemic countries, malaria occurs more frequently in non-endemic regions. It is a challenge for diagnostic laboratories in non-endemic countries to provide reliable results, as experience of staff is often limited to only a few cases per year. This study evaluated the diagnostic accuracy of the fully automated Sysmex XN-31 malaria analyzer in a routine diagnostic setting in a non-endemic region was evaluated.

Methods

Samples from 112 patients suspected for malaria were examined by the Sysmex XN-31 analyzer to determine the absolute count of malaria-infected red blood cells count (MI-RBC/µL). Microscopic examination of both Quantitative Buffy Coat capillary tubes and thick and thin blood films were used as reference methods. Limits of blank (LoB), detection (LoD) and quantification (LoQ) were investigated using an in vitro Plasmodium falciparum culture. Nine hundred twenty samples of patients with RBC abnormalities were included to determine which RBC abnormalities trigger indeterminate or false positive results.

Results

No false positive nor false negative results were obtained for the examined patient samples suspected for malaria. For 3% of samples an indeterminate result by the XN-31 was obtained. The Passing-Bablok regression line for diagnostic accuracy of the parasitaemia was y = 39.75 + 0.7892 × showing a positive bias of about 21% when comparing the MI-RBC results to microscopy. The LoB, LoD and LoQ were calculated to be 4.7, 5.9, and 19.0 infected RBC/μL, respectively. From the 920 abnormal RBC samples collected, 4.6% resulted in a false positive MI-RBC result and almost half of the samples produced indeterminate results. These results were related to increases in nucleated red blood cells, reticulocytes and other abnormal RBC morphologies such as sickle cells.

Conclusions

Based on the results, the XN-31 is a fast and reliable screening method in the detection and quantification of Plasmodium species in patients However, if an abnormal red blood cell morphology is present, the results of the XN-31 should be interpreted with caution as false positive results can be caused by interfering abnormal erythrocytes.

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.

Evolutionary history of sickle-cell mutation: implications for global genetic medicine

Resistance afforded by the sickle-cell trait against severe malaria has led to high frequencies of the sickle-cell mutation [HBB; c.20T>A, p.Glu6Val; OMIM: 141900 (HBB-βS)] in most parts of Africa. High-coverage sequencing and genotype data have now confirmed the single African origin of the sickle-cell gene variant [HBB; c.20T>A, p.Glu6Val; OMIM: 141900 (HBB-βS)]. Nevertheless, the classical HBB-like genes cluster haplotypes remain a rich source of HBB-βS evolutionary information. The overlapping distribution of HBB-βS and other disease-associated variants means that their evolutionary genetics must be investigated concurrently. In this review: (1) we explore the evolutionary history of HBB-βS and its implications in understanding human migration within and out of Africa: e.g. HBB haplotypes and recent migration paths of the Bantu expansion, occurrence of ~7% of the Senegal haplotype in Angola reflecting changes in population/SCD dynamics, and existence of all five classical HBB haplotype in Cameroon and Egypt suggesting a much longer presence of HBB-βS in these regions; (2) we discuss the time estimates of the emergence of HBB-βS in Africa and finally, (3) we discuss implications for genetic medicine in understanding complex epistatic interactions between HBB-βS and other gene variants selected under environmental pressure in Africa e.g. variants in HBB, HBA, G6PD, APOL1, APOE, OSBPL10 and RXRA.

Haematological abnormalities in children with sickle cell disease and non-severe malaria infection in western Kenya

Background

In Plasmodium falciparum infection, clinical conditions such as anaemia, thrombocytopenia and leukocytosis are common. Mutation in haemoglobin sub-unit beta gene (HBB) may be a genetic factor responsible for these haematological changes during infection. However, the contributions of the carriage of different HBB genotypes on these changes remain largely unknown.

Methodology

In this cross-sectional study, we evaluated haematological abnormalities in P. falciparum-infected children (n = 217, aged 1–192 months) with different haemoglobin sub-unit beta (HBB) genotypes (HbAA, HbAS and HbSS). Children with acute febrile conditions were recruited at Jaramogi Oginga Odinga Teaching and Referral Hospital at the outpatient clinic. Haematological parameters were determined using Beckman Coulter counter ACTdiff2™ while HBB genotyping was done using TaqMan® SNP genotyping assay. Chi-square (χ²) 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. Partial correlation test was used to determine correlation between haematological parameters and sickle cell genotypes while controlling for age and sex.

Results

Haemoglobin (Hb), [median (IQR); 7.3 (1.3), P = 0.001], haematocrit (HCT), [median (IQR); 26.4 (4.4), P = 0.009], red blood cells (RBC), [median (IQR); 3.2 (1.7), P = 0.048] were markedly reduced in HbSS, however, red cell distribution with (RDW) [median (IQR); 14.9 (3.3), P = 0.030] was increased in malaria infected children with HbSS. Severe anaemia was highest in HbSS (23.1%) followed by HbAA (8.6%) and HbAS (7.1%). There were no differences in platelet count (P = 0.399) hence no severe thrombocytopeania across the genotypes. Leukocytosis was highest in HbSS (69.2%), 42% in HbAS and 31% in HbAA. The RBC, HCT and Hb had negative correlation with RDW in HbSS in malarial-infected children (r = − 0.725, P = 0.008), (r = − 0.718, P = 0.009) and (r = − 0.792, P = 0.002), respectively.

Conclusion

Our study reveals that anaemia is the most common abnormality in malaria-infected children with carriage of HbSS. The RBC, HCT and Hb concentration decrease with increase in RDW levels in infected children with carriage of HbSS compared to other HBB genotypes. Therefore, carriage of HbSS genotype is correlated with severity of haematological abnormalities.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12879-021-06025-7.

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.