PROGRESS AND CHALLENGES IN AFRICA AT THE TIME OF MOLECULAR HAEMATOLOGY

The study of blood diseases has been traditionally at the border between clinical medicine and laboratory science. Many of us have been attracted to haematology by this combination: by the very fact that from examining a patient and looking at the blood picture it is often possible to make a diagnosis. As for understanding the nature of any disease, there are several layers: but since the middle of the last century, when the phrase ‘molecular disease’ was coined to aptly describe the basis of sickle cell anaemia,1 it became clear that in understanding the causes and the pathogenetic mechanisms of any disease the ultimate layer must be molecular.
From the middle of the last century African pioneers of haematology have been prominent: without detracting from others, let me mention Alex Boyo in Nigeria,2 Felix Konotey-Ahulu in Ghana,3 Edward Kasili in Kenya,4 Aloysius Nhonoli in Tanzania,5 Charles Olweny in Uganda6: as I have been fortunate to know each one of them in person. As clinical and epidemiological studies were being conducted, the pattern of blood disorders in sub-Saharan Africa (SSA) gradually emerged, and it had several important features. First, as could be expected, an African patient with megaloblastic anaemia, or one with thrombocytopenic purpura, or one with Hodgkin disease, or one with any other specific blood disease was not much different from a patient with the same disease in any other part of the world. Second, in contrast to clinical similarity, the prevalence of many blood conditions was very different: first and foremost, anaemia was and still is rampant,7 due to a variety of infectious and nutritional causes, and it is of great clinical importance particularly in children and in pregnancy.8 Third, whereas in USA and in Europe haemoglobinopathies are officially ‘rare diseases’, in many countries in SSA the prevalence of sickle cell disease (SCD) at birth is from 1 to 2%: with millions of people affected, it is a major public health problem. Fourth, a unique haematologic malignancy, Burkitt’s lymphoma, was discovered in Africa.9 Last, in SSA, and especially in West Africa, endemic malaria, in addition to being a major cause of mortality in children, is always in the background: during my first couple of years at UCH in Ibadan, when I regarded myself as being still very much in training, I learnt that when a patient had a fever the question was not whether he or she had malaria: rather, whether it was just malaria or also something else on top.

血液疾病研究历来处于临床医学与实验医学的交界地带。许多人正是被这一交叉属性所吸引投身血液学：通过问诊患者并观察血象，往往即可作出诊断。就理解疾病本质而言，可分为多个层级；但自上世纪中叶“分子病”一词被创造出来，用以恰当地描述镰状细胞贫血（sickle cell anaemia）的发病基础以来¹，人们逐渐明确：要理解任何疾病的病因与致病机制，最终都需追溯至分子层面。

上世纪中叶以来，非洲血液学先驱始终占据重要地位。在此无意贬低其他学者，谨提及尼日利亚的亚历克斯·博约（Alex Boyo）²、加纳的费利克斯·科诺泰-阿胡卢（Felix Konotey-Ahulu）³、肯尼亚的爱德华·卡西利（Edward Kasili）⁴、坦桑尼亚的阿洛伊斯·恩霍诺利（Aloysius Nhonoli）⁵以及乌干达的查尔斯·奥尔温伊（Charles Olweny）⁶——笔者有幸与诸位均有过当面交流。随着临床与流行病学研究的推进，撒哈拉以南非洲（sub-Saharan Africa, SSA）的血液疾病谱逐渐清晰，展现出多项显著特征：其一，与预期相符，非洲患者罹患巨幼细胞性贫血、血小板减少性紫癜、霍奇金病或其他特定血液疾病时，其临床表现与全球其他地区的同类患者并无显著差异。其二，尽管临床表现相似，但诸多血液疾病的患病率却大相径庭：首要且突出的是贫血至今仍广泛流行⁷，其病因涵盖多种感染与营养性因素，在儿童与孕妇群体中临床意义尤为重大⁸。其三，与欧美地区将血红蛋白病列为官方“罕见病”不同，撒哈拉以南非洲诸多国家的新生儿镰状细胞病（sickle cell disease, SCD）患病率达1%至2%，受影响人群数以百万计，已成为重大公共卫生问题。其四，非洲发现了一种独特的血液系统恶性肿瘤——伯基特淋巴瘤（Burkitt’s lymphoma）⁹。最后，在撒哈拉以南非洲，尤其是西非地区，地方性疟疾除了是儿童主要致死病因之一外，始终是临床背景中不可忽视的因素：笔者在伊巴丹大学学院医院（UCH）工作的最初两年，尚处于进修阶段时便深知，当患者出现发热时，临床医师无需追问其是否罹患疟疾，而应判断其究竟仅为疟疾，还是同时合并其他病症。