Malaria can be transmitted by blood transfusion from human to human and it is responsible for the majority of transfusion-transmitted infectious diseases worldwide. In sub-Saharan Africa, it had been estimated that almost a quarter of blood donations contain malaria parasites. Since rapid diagnostic tests and thick blood smear microscopy lack sensitivity for low density parasitaemia, particularly in asymptomatic adults, the most reliable method to assess the problem of transfusion-transmitted malaria are nucleic acid-based molecular approaches such as quantitative polymerase chain reaction. The study was undertaken to determine the prevalence of sub-microscopic malaria parasite infection among blood donors in Malabo, Equatorial Guinea. Between July and August 2017, a total of 200 individual blood samples from blood donors at the Malabo Blood Bank were collected and screened by rapid diagnostic tests and thick blood smear microscopy. Retrospectively, the same samples were analysed for the presence of undetected, low-density malaria parasites using quantitative polymerase chain reaction. In comparison to 6.5% (13/200) by rapid diagnostic test and 2.0% (4/200) by microscopy, the proportion of Plasmodium falciparum positive blood donations analysed by quantitative polymerase chain reaction was significantly higher (26%, 52/200). Densities of P. falciparum positive blood donations were ranging from 0.06 to 3707.0 parasites/µL with 79.6% below 100 parasites/µL and therefore not detectable by non-molecular malaria diagnostic tests. qPCR based species identification revealed that P. falciparum was the dominating species responsible for 88.1% (52/59) of positive blood donations, followed by Plasmodium malariae (15.3%, 9/59) and Plasmodium ovale (3.4%, 2/59). This study confirms that in malaria endemic settings, sub-patent malaria infections among blood donors are prevalent. In blood collected from healthy donors living in Malabo, P. falciparum, P. malariae and P. ovale parasites were identified. Currently widely used malaria diagnostic tools have missed more than 75% of P. falciparum containing blood donations, demonstrating the value of quantitative polymerase chain reaction to reliably detect low density P. falciparum infections. Since the availability of molecular diagnostic methods in malaria endemic countries is still limited, the blood recipients living in malaria endemic countries should be treated following WHO recommendations.

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Molecular monitoring of the diversity of human pathogenic malaria species in blood donations on Bioko Island, Equatorial Guinea.

To provide a focused review of sickle cell retinopathy in the light of recent advances in the pathogenesis, multimodal retinal imaging, management of the condition, and migration trends, which may lead to increased prevalence of the condition in the Western world. Non-systematic focused literature review. Sickle retinopathy results from aggregation of abnormal hemoglobin in the red blood cells in the retinal microcirculation, leading to reduced deformability of the red blood cells, stagnant blood flow in the retinal precapillary arterioles, thrombosis, and ischemia. This may be precipitated by hypoxia, acidosis, and hyperosmolarity. Sickle retinopathy may result in sight threatening complications, such as paracentral middle maculopathy or sequelae of proliferative retinopathy, such as vitreous hemorrhage and retinal detachment. New imaging modalities, such as wide-field imaging and optical coherence tomography angiography, have revealed the microstructural features of sickle retinopathy, enabling earlier diagnosis. The vascular growth factor ANGPTL-4 has recently been identified as a potential mediator of progression to proliferative retinopathy and may represent a possible therapeutic target. Laser therapy should be considered for proliferative retinopathy in order to prevent visual loss; however, the evidence is not very strong. With recent development of wide-field imaging, targeted laser to ischemic retina may prove to be beneficial. Exact control of intraoperative intraocular pressure, including valved trocar vitrectomy systems, may improve the outcomes of vitreoretinal surgery for complications, such as vitreous hemorrhage and retinal detachment. Stem cell transplantation and gene therapy are potentially curative treatments, which may prevent retinopathy. There is lack of evidence regarding the optimal management of sickle retinopathy. Further study is needed to determine if recent progress in the understanding of the pathophysiology and diagnosis of sickle retinopathy may translate into improved management and outcome.

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Sickle cell retinopathy. A focused review.

In an effort to explore new knowledge and to develop meaningful collaborations for improving child health, the First Pan African Workshop on Newborn Screening was convened in June 2019 in Rabat, Morocco. Participants included an informal network of newborn screening stakeholders from across Africa and global experts in newborn screening and sickle cell disease. Over 150 attendees, representing 20 countries, were present including 11 African countries. The agenda focused on newborn screening rationale, techniques, system development, implementation barriers, ongoing research, and collaborations both globally and across Africa. We provide an overview of the workshop and a description of the newborn screening activities in the 11 African countries represented at the workshop, with a focus on sickle cell disease.

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Empowering newborn screening programs in African countries through establishment of an international collaborative effort.

Sickle cell retinopathy (SCR) is the most representative ophthalmologic complication of sickle cell disease (SCD), a hemoglobinopathy affecting both adults and children. SCR presents a wide spectrum of manifestations and may even lead to irreversible vision loss if not properly diagnosed and treated at the earliest. Over the past decade, multidisciplinary research developments have focused upon systemic, genetic, and ocular risk factors of SCR, enabling the clinician to better diagnose and manage these patients. In addition, newer imaging and testing modalities, such as spectral domain-optical coherence tomography angiography, have resulted in the detection of subclinical retinopathy related to SCD. Innovative therapy includes intravitreal injection of an anti-vascular endothelial growth factor (eg, Lucentis® [ranibizumab] or Eylea® [aflibercept]) which appears comparatively safe and efficient, and may be combined with laser photocoagulation (LPC) for proliferative SCR. The effect of LPC alone does not significantly lead to the regression of advanced SCR, although it helps in avoiding hemorrhage and sight loss. This comprehensive article is based on 10-years retrospective (2007-2017) studies. It aims to present advances and recommendations in SCR theranostics while pointing out the requirement of combinatorial approaches for better management of SCR patients. To reach this goal, we identified and analyzed randomized original and review articles, clinical trials, non-randomized intervention studies, and observational studies using specified keywords in various databases (eg, Medline, Embase, Cochrane, ClinicalTrials.gov).

https://www.dovepress.com/getfile.php?fileID=38184

Sickle cell retinopathy: improving care with a multidisciplinary approach.

Clinical and Ophthalmic Factors Associated With the Severity of Sickle Cell Retinopathy

Resume Introduction La retinopathie est une complication chronique a risque fonctionnel important chez le drepanocytaire, dont l’incidence est mal connue en Afrique subsaharienne, faute de depistage. Ce travail decrit les resultats d’un depistage systematique de la retinopathie drepanocytaire dans un centre de suivi des drepanocytaires au Mali. Methodes Tous les drepanocytaires âges de 10 ans et plus, suivis au centre, ont ete depistes entre 2010 et 2012 par un examen du fond d’œil complete si besoin par une angiographie. Les caracteristiques des patients porteurs d’une retinopathie ont ete comparees a celles de drepanocytaires sans retinopathie recrutes durant la meme periode et selectionnes au hasard. Resultats La retinopathie avait une prevalence globale de 8,8 % chez les 1604 drepanocytaires âges de 10 ans et plus et concernait 91/731 (12,4 %) drepanocytaires SC, 38/734 (5,2 %) SS, 5/53 (9,4 %) Sβ 0  thalassemiques et 8/86 (9,3 %) Sβ +  thalassemiques. La forme proliferante de la retinopathie etait plus frequente chez les SC ( p 0 thalassemiques. Conclusion La retinopathie touche pres d’un patient drepanocytaire sur dix et sa prevalence est negativement associee au taux d’hemoglobine fœtale. L’efficience d’un depistage systematique de la retinopathie drepanocytaire doit etre etudiee en Afrique, ainsi que l’interet de la phlebotomie et de l’hydroxycarbamide en traitement preventif.

Prévalence et facteurs de risque de la rétinopathie drépanocytaire dans un centre de suivi drépanocytaire d’Afrique subsaharienne

Resume Position du probleme Le depistage neonatal de la drepanocytose s’impose en Afrique ou la maladie est plus frequente. L’electrophorese de l’hemoglobine permet ce depistage, mais son usage est limite par un cout eleve et des difficultes d’acces. Le test d’Emmel, plus abordable et techniquement plus accessible est souvent demande dans le bilan prenatal des gestantes en Afrique, pour reserver le depistage aux nouveau-nes issus de meres chez qui le test positif atteste la presence d’hemoglobine S. Cette etude se propose d’evaluer le nombre de naissances drepanocytaires non reperees dans le cadre d’une politique de depistage ciblant les seules naissances issues de meres chez qui le test d’Emmel serait positif. Methodes De 2010 a 2012, a Bamako, Mali, 2489 nouveau-nes ont fait l’objet d’un depistage systematique de la drepanocytose, au niveau du cordon ombilical ou du talon, par isoelectrofocalisation, completee au besoin par une chromatographie liquide haute performance. Ces nouveau-nes etaient issus de 2420 meres dont l’hemoglobinique a ete etudiee par isoelectrofocalisation. Les donnees ont ete enregistrees et traitees a l’aide du logiciel Excel dans sa version 14.0.0. Nous avons calcule la frequence du gene drepanocytaire chez les populations des meres et des nouveau-nes depistes ainsi que le nombre de nouveau-nes drepanocytaires nes de meres heterozygotes ou homozygotes C. Resultats Parmi les 2489 nouveau-nes, 16 etaient drepanocytaires majeurs dont 6 SS et 10 SC ; 198 avaient le trait drepanocytaire ; 139 etaient AC et 1 etait CC. Parmi les 10 drepanocytaires majeurs SC, 3 etaient nes de meres n’ayant pas le drepanocytaire S, mais porteuses du gene C de l’hemoglobine et chez lesquelles, un test d’Emmel aurait ete negatif. Conclusion Un depistage neonatal cible, base sur les resultats du test d’Emmel chez les femmes enceintes, meconnaitrait plus d’un drepanocytaire majeur sur six qui serait ainsi prive d’une prise en charge adaptee precoce. Des etudes de rapport cout/efficacite d’un depistage neonatal systematique de la drepanocytose doivent conduire a une meilleure strategie de depistage a adopter dans les contextes ou la mutation S coexiste avec d’autres mutants hemoglobiniques.

Targeted newborn screening for sickle-cell anemia: sickling test (Emmel test) boundaries in the prenatal assessment in West African area.

Dear Sir, Sickle cell disease (SCD) is a common worldwide inherited haematologic disorder. Blood transfusion therapy is an essential component in SCD management particularly during vaso-occlusive crisis, acute chest syndrome and cerebral vasculopathy prevention. According to De Montalembert, over 60% of homozygous (SS) SCD patients, 17% of heterozygote SC and 45% of S/Beta-thalassemia patients have been transfused at least once before they are 18 years old. Despite progresses achieved during the last decades in improving blood transfusion safety, it still represents a risk for the recipient, as it can result in transmission of various pathogens including Plasmodium falciparum (Pf ). Pf can withstand storage at 4 ∘C for at least 3 weeks as well as survive in asymptomatic individuals willing to donate blood. In non-endemic areas, prevention of post-transfusion malaria (PTM) is carried out by permanent or temporary exclusion of blood donors who stayed even briefly in endemic areas (Garraud et al., 2007). The health of blood donors is of paramount importance for both the donor and the recipient; hence, screening for Pf in malaria-endemic areas may increase the safety of blood transfusion. However, despite the risk of blood transmitted Pf infection in sub-Saharan Africa and in spite of the established World Health Organization recommendations (Kitchen and Chiodini, 2006), no systematic screening for Pf is presently conducted by transfusion centres and few studies have been carried out on the risk of transfusion-transmitted Pf . The potential use of Pf -infected blood units in malaria-endemic areas for SCD-affected patients raises an ethical issue which needs to be addressed by the scientific community. In a 2014 report from Brazil, only four cases of malaria transmission by transfusions were identified since 2002 (Lacerda et al., 2014). We report here our findings from a systematic screening for Pf in concentrated red blood cell (CRBC) units collected for transfusion during the management of SCD-affected individuals in Mali. The aim of this study was to evaluate the risk of transmission of Pf by blood transfusion in SCD patients living in malaria-endemic areas. From January to December of 2013 (covering low and high malaria transmission season in Mali), a cross-sectional study was

A. Guindo

Papers

Prévalence et facteurs de risque de la rétinopathie drépanocytaire dans un centre de suivi drépanocytaire d’Afrique subsaharienne

Targeted newborn screening for sickle-cell anemia: sickling test (Emmel test) boundaries in the prenatal assessment in West African area.

Transmission of Plasmodium falciparum by red blood cell transfusions in the management of sickle cell disease patients in Mali.