Haematology in Africa

All diseases result from our genes and from the environment. This is conventional teaching for first year medical students: and if the medical school is in Africa it is hard to find a better example than blood diseases, given that in Africa, on one hand, haemoglobinopathies affect millions of people (WHO Working Group, 1982), while on the other hand, malaria, hookworm and nutritional deficiency (folate, or iron or both) are the main causes of anaemia (Boele van Hensbroek et al, 2010). In medical school we must also deal with the role of Darwinian selection in evolution. This is a central thread throughout biology, and almost everyone agrees it applies extensively also to the human species: yet, when it comes to giving an example, whether the class is held in Africa or elsewhere, the teacher will fall back on how the haemoglobin S gene has been selected in tropical areas through the relative resistance it confers to heterozygotes against Plasmodium falciparum (see Fig 1 and Luzzatto, 1979). This paper is not a review, but a commentary; given that Africa is a vast and variegated continent, we have concentrated on its tropical area – or, as from a phrase customary during the last century, Africa ‘south of the Sahara and north of the Zambesi’. So what are the issues faced by the practicing haematologist in Africa today? The short answer is, exactly the same as those faced by a haematologist in any other part of the world: only a little more complicated, for two reasons. (i) Tropical diseases are not in lieu, but in addition to those that prevail in temperate climates. It has long been the practice anywhere within the rain forest belt that, when a newly admitted patient has a high fever the question is not whether he needs treatment for malaria, but whether the fever is due ‘just’ to malaria (Esan, 1975) or to other additional factors. Example of co-morbidity we remember include a patient who had HbSC disease and chronic myeloid leukaemia (see also (Rosner & Grünwald, 1989); patients who had both tuberculosis and lymphoma (see Omoti et al, 2009); a patient with sickle cell anaemia who was at risk of dying from malaria (see McAuley et al, 2010); a young woman with anaemia in pregnancy who was found to have paroxysmal haemoglobinuria and developed fulminating amoebiasis (Oni et al, 1970). In the Northern part of the world co-morbidity is quoted often as a troublesome component common in oncological practice in the elderly; in Africa co-morbidity can be the rule rather than the exception at any age. (ii) Many patients need haematological attention for problems that may have a precise aetiology, but that have in fact developed essentially as a result of socio-economic reasons, as has also happened abundantly elsewhere. For instance, hookworm anaemia is a specific diagnosis: but when Italian workers digging the Gotthard tunnel in the late 19th century became paler and paler until they died it was called miners’ anaemia or tunnel disease. Once Camillo Bozzolo, Edoardo Perroncito, and Luigi Pagliani correctly surmised that the spread of the disease had something to do with the workers wearing worn-out shoes and being forced to defecate inside the 15 km tunnel, the problem was quickly solved (Parona, 1894). Today in Africa the same condition, hookworm anaemia, could be called the barefoot farmer’s anaemia: should it be treated by the administration of mebendazole and iron or would it be better for farmers to have proper footwear? Today in Africa the spectrum of blood diseases is largely similar to that of the rest of the world, but disease presentation may be considerably modified by socioeconomic and cultural factors (see Figs 2 and 3). In practice, this often means late presentation with advanced disease, and in some cases even mutilation, particularly with neoplastic disease. The same factors also influence the rate of patients who discharge themselves or their children against medical advice, and the degree of compliance of patients with treatment protocols and follow up (Diagne et al, 2003): in these respects the role of social workers is paramount and their services ought to be much enhanced. Fig 1. Plasmodium falciparum infection in a girl heterozygous for Glucose-6-phosphate dehydrogenase (G6PD) deficiency. The blood film was stained by a procedure that causes lysis of G6PD-deficient red cells, producing their ghost-like appearance. As G6PD deficiency heterozygosity is a somatic cell mosaic as a result of X chromosome inactivation it was possible to show by this procedure that P. falciparum parasitized red cells are predominantly G6PD normal (see Luzzatto et al, 1969). editorial comment