■尽管已经描述了血红蛋白S的保护作用,疟疾经常与非洲镰状细胞病患者的发病率和死亡率增加有关。在这些患者的血常规上经常发现各种血细胞减少症。在贝宁,镰状细胞病患病率高的疟疾流行区,本研究的目的是根据血红蛋白类型建立和比较镰状细胞病和疟疾相关性的血细胞计数谱。
■这是一项前瞻性描述性研究。它涵盖了从2020年10月到2022年10月的24个月。它包括所有在临床血液学中看到的大镰状细胞综合征的患者,并且具有阳性的厚滴/寄生虫密度,不管寄生虫血症的价值。对于每个病人来说,在SysmexXT4000i机器上进行了血液计数,用May-GrunwaldGiemsa染色后进行涂片研究。数据采用R3.6.1软件进行分析。
■在镰状细胞患者中发现了300例厚涂片阳性的非冗余病例,包括208个SS纯合子(69.3%)和92个SC杂合子(30.7%)。相比之下,有181例非冗余病例,厚涂片阴性,包括119个SS纯合子(65.7%)和62个SC杂合子(34.3%)。在厚涂片阳性的受试者中,大多数患者(70%)表现出临床症状。在58%的病例中观察到严重的疟疾。SS纯合子患者的重症疟疾比例高于双杂合子SC患者(p<0.0001)。SS个体的平均寄生虫密度(4320.7±2185滋养体/pL)高于SC个体(1564.4±1221滋养体/pL;p<0.0001)。恶性疟原虫是唯一确定的物种。穿刺SS受试者的平均血红蛋白水平为6.1g/dL,显著低于非穿刺SS受试者(p<0.0001)。穿刺的SS受试者的平均白细胞计数为16.58G/L,与具有阴性厚涂片的13.2G/L相比(p<0.0001)。在厚片涂片阳性的SS受试者中发现20例血小板减少症,相比之下,厚片涂片阴性的6例。至于厚涂片阳性的SC受试者,平均血红蛋白水平和白细胞计数分别为9.8g/dL和10.63g/L,分别,与阴性厚涂片的SC受试者相比,为11.27g/dL和7.3g/L。在厚涂片阳性的受试者中发现了18例血小板减少症,相比之下,厚片阴性的17例。
镰状细胞病和疟疾是两个主要的公共卫生问题。然而,与普遍的看法相反,镰状细胞病对疟疾的侵扰并不免疫。疟疾被认为是镰状细胞患者发病和死亡的主要原因之一,尤其是儿童。在贝宁,它与镰状细胞紧急情况的关联已经被报道。我们的研究发现疟疾主要与纯合SS形式相关(p<0.00001)。重症疟疾是最常见的临床形式。我们系列中所有的疟疾感染都是由恶性疟原虫引起的,SS患者中寄生虫血症明显增高(p<0.0001)。在我们的系列中,纯合子SS个体中镰状细胞病和疟疾的相关性的血液学特征显示出具有中性粒细胞占优势的白细胞增多的正常细胞正常色素性贫血的特征。与非疟疾感染的SS个体相比,贫血严重恶化,中性粒细胞占优势的白细胞增多,和平均血小板计数下降。在SC个人中,与中性粒细胞占优势的白细胞增多相关的小细胞性正色素性再生性贫血.与非疟疾感染的SC个体相比,贫血和以中性粒细胞为主的白细胞增多率显著下降.贫血是纯合镰状细胞病的一个恒定特征,记录的低值说明了疟疾的溶血性质,特别是在党卫军个体中,以及SC个体更好的容忍度。此外,与SC个体相比,低基线血红蛋白水平使SS个体更容易患疟疾引起的贫血.在大镰状细胞综合征的情况下,观察到的白细胞增多通常伴有网织红细胞增多症,必须考虑结果验证。它是对疟疾感染引起的贫血和炎症机制的代偿性骨髓反应的表达。最后,血小板减少在SC患者中更为常见,即使他们是生活在疟疾流行地区的成年人。在“玫瑰花形”现象期间,疟疾经常通过血小板消耗引起血小板减少症。在SS患者中,“玫瑰花结”的作用可以通过贫血引起的骨髓刺激来补偿。在我们的系列中,成年受试者生活在流行地区,血小板减少不是常见的生物学障碍。在SS或SC镰状细胞患者中,全身性炎症反应综合征与贫血和中性粒细胞占优势的白细胞增多相结合的临床生物学背景下,临床医生应该能够考虑疟疾,并确认或排除这种诊断。
Although a protective effect of hemoglobin S has been described, malaria has frequently been associated with increased morbidity and mortality in sickle cell disease patients in Africa. Various cytopenias are frequently found on the haemograms of these patients. In Benin, a malaria-endemic zone with a high prevalence of sickle cell disease, the aim of this study was to establish and compare the blood count profile according to hemoglobin type in the association of sickle cell disease and malaria.
This was a prospective descriptive study. It covered a 24-month period from October 2020 to October 2022. It included all patients with major sickle cell syndrome seen in clinical haematology and with a positive thick drop/parasite density, whatever the parasitaemia value. For each patient, a blood count was performed on the Sysmex XT 4000i machine, supplemented by a smear study after staining with May-Grunwald Giemsa. Data were analyzed using R 3.6.1 software.
Three hundred non-redundant cases with a positive thick smear were identified in sickle cell patients, including 208 SS homozygotes (69.3%) and 92 SC heterozygotes (30.7%). In contrast, there were 181 non-redundant cases with a negative thick smear, including 119 SS homozygotes (65.7%) and 62 SC heterozygotes (34.3%). Among subjects with a positive thick smear, the majority of patients (70%) exhibited clinical symptoms. Severe malaria was observed in 58% of the cases. The proportion of severe malaria was higher in SS homozygote patients than in double heterozygote SC patients (p < 0.0001). The mean parasite density was higher in SS individuals (4 320.7 ± 2 185 trophozoites/pL) compared to SC individuals (1 564.4 ± 1 221 trophozoites/pL; p < 0.0001). Plasmodium falciparum was the only species identified. The mean hemoglobin level in impaludated SS subjects was 6.1 g/dL, significantly lower than that in non-impaludated SS subjects (p < 0.0001). The average white blood cell count in impaludated SS subjects was 16.58 G/L, compared to 13.2 G/L in those with a negative thick smear (p < 0.0001). Twenty cases of thrombocytopenia were found in SS subjects with a positive thick smear, compared to 6 cases in those with a negative thick smear. As for SC subjects with a positive thick smear, the average hemoglobin levels and white blood cell counts were 9.8 g/dL and 10.63 G/L, respectively, compared to 11.27 g/dL and 7.3 G/L in SC subjects with a negative thick smear. Eighteen cases of thrombocytopenia were found in subjects with a positive thick smear, compared to 17 cases in those with a negative thick smear.
Sickle cell disease and malaria represent two major public health problems. However, contrary to popular belief, sickle cell disease is not immune to malaria infestation. Malaria is recognized as one of the main causes of morbidity and mortality in sickle cell patients, particularly children. In Benin, its association with sickle cell emergencies has already been reported.Our study found that malaria was predominantly associated with the homozygous SS form (p < 0.00001). Severe malaria was the most common clinical form. All malaria infestations in our series were due to Plasmodium falciparum, and parasitaemia was significantly higher in SS patients (p < 0.0001).The hematological profile of the association of sickle cell disease and malaria in homozygous SS individuals in our series showed characteristics of a normocytic normochromic anemia with neutrophil-predominant leukocytosis. Compared to non-malaria-infected SS individuals, there was a significant worsening of anemia, neutrophil-predominant leukocytosis, and a decrease in the average platelet count. In SC individuals, there was rather a microcytic normochromic regenerative anemia associated with neutrophil-predominant leukocytosis. Compared to non-malaria-infected SC individuals, there was a significant decrease in the rate of anemia and neutrophil-predominant leukocytosis. Anemia is a constant feature in homozygous sickle cell disease, and the low values recorded illustrate the hemolytic nature of malaria, especially in SS individuals, and the better tolerance of SC individuals. Furthermore, the low baseline hemoglobin levels make SS individuals more vulnerable to malaria-induced anemia compared to SC individuals. The observed leukocytosis is generally accompanied by reticulocytosis in the case of major sickle cell syndrome, which must be taken into account for result validation. It is the expression of compensatory bone marrow reaction to anemia and inflammatory mechanisms resulting from malaria infestation. Finally, thrombocytopenia was significantly more common in SC patients, even though they were adults living in malaria-endemic areas. Malaria can frequently induce thrombocytopenia through platelet consumption during the \"rosetting\" phenomenon. In SS patients, the effects of \"rosetting\" could be compensated for by the bone marrow stimulation induced by anemia. In our series with adult subjects living in an endemic area, thrombocytopenia is not a frequent biological disturbance. In a clinicalbiological context combining a systemic inflammatory response syndrome with anemia and neutrophil-predominant leukocytosis in a SS or SC sickle cell patient, the clinician should be able to consider malaria and confirm or rule out this diagnosis.