![]()
1 Sickle cell and the complications of science
This first chapter introduces the basics of sickle cell for the non-specialist reader. It starts from the types of information devised for public health consumption, but then notes ways in which this information has been simplified. For example, the chapter covers the following differences:
ā¢ between sickling and ānormal sicklingā;
ā¢ between sickling considered as a blockage of sickled cells versus sickling as a set of complex physiological interactions;
ā¢ between concepts of genotype and phenotype;
ā¢ between the focus on sickle cell painful crises as the emblematic symptom of sickle cell and other major sickle cell complications;
ā¢ between theoretical probability in patterns of inheritance and empirical occurrence.
The gap between popular community health education and science has been explained in various ways: as a response necessary to account for the technical ignorance of āthe publicā, or as impartial professionals protecting the public from the overwhelming complexity of reality. The chapter concludes by identifying the need for change in the way scientific practice is understood by scientists themselves, in order to move beyond the militaristic-paternalistic sounding model of āpublic engagementā that currently dominates the relationship between professionals, scientific knowledge and the people.
Sickle cell disease/sickle cell disorder (SCD)
Sickle cell disease/sickle cell disorder (SCD) is an umbrella term denoting a family of severe, inherited, chronic illnesses. The form that is found most frequently is called sickle cell anaemia, accounting for perhaps 70 per cent of SCD. But there are a number of other forms of SCD. One set is where the gene encoding sickle haemoglobin (haemoglobin S) is inherited together with a gene encoding another haemoglobin variant (haemoglobins C, D or E, for example). For instance, haemoglobin SC disease accounts for around 20 per cent of sickle cell disease. Still further types are where a gene associated with sickle cell is co-inherited with a form of thalassaemia. Thalassaemias are associated with a reduction in the quantity of the key oxygen-carrying component of red blood cells, haemoglobin, while haemoglobin variants, which include sickle cell, represent a qualitative change in the type of haemoglobin produced. The main conditions in sickle cell disease are listed in Table 1.1.
Sickle cell disease is the term of choice for clinicians. By contrast, some community-based organizations use the phrase sickle cell disorder (Clare, 2007). Three reasons appear to underlie this choice of words. First, ādiseaseā has implications of contagion, of being transmissible from person to person. My own early work on community awareness of sickle cell tried to underscore the idea that sickle cell is not caught like coughs or colds, but is a genetic condition inherited from both biological parents (Dyson, 1997). In this sense, using the word disorder tries to prevent inaccurate connotations of the word disease. Creary (2018) cites a Brazilian activist discursively reclaiming SCD as a ātrue black health issueā, precisely to distance it from HIV as an infectious disease, HIV/AIDS being ascribed, in racist discourses, to the black body (Sabatier, 1988). Second, part of the ideology of racism is that black people are reduced to only their bodies (Shilling, 1993) with allegedly limited interior psyches (Skeggs, 2014). Furthermore, such bodies are viewed through a racist lens as inherently diseased (Savitt, 2002). Since sickle cell might be partially described as a blood disease, this makes it vulnerable to being negatively linked to the infamous Tuskegee Syphilis study on African-American men. In this study, men with syphilis or ābad bloodā were permitted to die or go blind without treatment when that became available, in order for junior public health doctors to trace the (alleged) natural history of the disease (Reverby, 2000). The third reason is that sociologists, drawing upon insights of the social model of disability (about which more in Chapters 10 and 11), may choose the term disorder (Atkin and Ahmad, 2001). This is because one tenet of disability rights is to assert that disability is not an illness. A disease implies possibility of cure by a doctor, and the social model of disability criticizes medical models that seek cure or rehabilitation for disabled peoples (Oliver, 1998). Terming sickle cell a disorder has at least the potential to frame the issue as one of disablement: re-focusing on the rights of the disabled person concerned and changes to the collective environment. Re-framing the issue still further to emphasize the agency of the person with sickle cell produces terms like āsickle cell warriorā, in use at the time of writing in US community-based organizations. How something is referred to initiates our process of understanding and provides our first clue to which framings of sickle cell require resisting.
Table 1.1 Basic classification of sickle cell disease/sickle cell disorders
| Genotype notation |
| Sickle cell anaemia | HbS/S |
| Haemoglobin SC disease | HbS/C |
| Sickle beta-zero thalassaemia | HbS/Ī²0 |
| Sickle beta-plus thalassaemia | HbS/Ī²+ |
| Haemoglobin sickle cell/D-Punjab | HbS/D-Punjab |
| Haemoglobin sickle cell/E | HbS/E |
| Haemoglobin sickle cell/O-Arab | HbS/O-Arab |
Sickle cell symptoms
Sickle cell is referenced as the first molecular disease. A single change at the molecular level produces an altered form of haemoglobin (Pauling et al., 1949). Haemoglobin is the protein in our red blood cells that gives blood its red appearance. One of its tasks is to carry oxygen from the lungs to the rest of the body. The delivery of oxygen takes place in blood vessels (capillaries) which, at their narrowest, may be less than the width of a red blood cell. In people with usual adult haemoglobin (called haemoglobin A, abbreviated to HbA), the red blood cells remain sufficiently flexible to enable them to squeeze through the capillaries and transfer their oxygen. However, in people with sickle cell anaemia, a majority of the haemoglobin is sickle haemoglobin (called haemoglobin S or HbS). When the cell is not oxygenated, the haemoglobin no longer remains in solution but crystallizes into long twisted chains (a process called polymerization). Like a rigid stick within a balloon, these chains of haemoglobin distort the cell membrane into peculiar elongated shapes. When such chains are formed rapidly, the red blood cell becomes crescent-shaped like a sickle (the ancient agricultural tool for harvesting grasses). However, the particular shape depends partly on the speed with which the chains of haemoglobin stack up, and holly-leaf and granular forms are also possible (Serjeant and Serjeant, 2001: 64).
A simplified account would continue as follows. In contrast to usual red blood cells which are flexible and can squeeze through narrow blood vessels, sickle-shaped cells are rigid, and may create a log-jam in the capillaries, depriving that part of the body of oxygen. However, the dynamics of polymerization are generally too slow to result in sickling while the red blood cells are in the capillaries and vaso-occlusion (vaso-, to do with the blood vessels, and occlusive, concerned with closure or blocking) is not just related to this. The blockage of capillaries is not exclusively due to sickling but to a multicellular collaboration with the lining of the blood vessels (called the endothelium), and sickling occurs in conjunction with other physiological mechanisms (Eaton and Bunn, 2017). This is addressed more fully a little later in this chapter.
The consequence of these complex physiological processes is a symptom emblematic of the sickle cell experience: a sickle cell painful episode (vaso-occlusive episode). Such episodes are often referred to as a āsickle cell crisisā. The resultant pain may be mild, moderate or excruciating and may last minutes, hours or days. Painful episodes may be emblematic of sickle cell illness, but this draws attention away from other issues. The red blood cells are continually destroyed prematurely (haemolysis), the person is anaemic, and chronic fatigue is a neglected symptom of SCD. The cumulative effect of sickled red blood cells and periodic denial of oxygen is long-term damage to tissues and the possibility of organ failure. The consequences of SCD are thus far more extensive than acute painful sickle cell crises.
All parts of the body require oxygen delivered by red blood cells, so clearly anything that disrupts that process may produce pain at multiple sites in the body and, over time, may produce damage to tissues and organs. SCD is thus not just a blood disorder but a systemic disorder: it is the underlying mechanism that generates effects in nearly every part of the body. This diversity in empirical symptoms generated through underlying mechanisms partially explains why SCD remained hidden from the medical profession for so long (Wailoo and Pemberton, 2006).
Since SCD is a systemic disorder, people with SCD may experience acute or chronic pain in any part of the body. They may experience a truly daunting range of symptoms: strokes caused by bleeds or blockages; silent strokes; loss of the spleen (or splenic function) leading to vulnerability to infections; severe anaemia; acute chest syndrome; hand-foot syndrome; leg ulcers, necrosis (necrosis: death of body tissue) of the shoulders or hip joints, visual or hearing problems, damage to the kidney or the liver, among many other symptoms and complications (Serjeant and Serjeant, 2001). There are also other types of sickle cell crises other than acute painful episodes. A splenic sequestration crisis involves red blood cells becoming trapped in the spleen, leading to a painful enlargement of the spleen, and constituting a medical emergency. Education of parents to recognize this is part of the newborn screening for sickle cell discussed further in Chapter 9. An aplastic crisis involves parvovirus B19 and the collapse in the production of red blood cells. Understandably, much focus is on the immediacy of the acute painful sickle cell crisis, but SCD is also a progressive disorder: repeated infarctions damage key organs over time, and people living with SCD can be faced with the challenges of long-term organ damage.
Nor is the acute sickle cell painful crisis the only source of sickle cell-related pain. In addition to acute pain, people with SCD experience chronic pain and neuropathic pain, that is, pain caused by damage to the central nervous system, which then renders the person hypersensitive to future pain (Ballas et al., 2012). One study in the USA suggests that in people with SCD nearly one-third describe sickle cell pain every day; over 50 per cent report pain on more than half of the days; and only one in seven rarely experience chronic pain (Smith et al., 2008). However, we also need to be cautious that people with SCD in a US social environment of relative poverty and racism do not necessarily stand for the global experience of people with SCD in other settings. With respect to both range of symptoms and types of pain, and to physical and collective environments, the sickle cell illness experience is about more than acute painful episodes.
Treatment for sickle cell disorders
The treatment for sickle cell disorders reflects in turn the wide range of clinical symptoms that can affect people living with SCD. It has been suggested that only specialist sickle cell centres can adequately provide comprehensive care for people with SCD, so extensive is the spectrum of medical, psychological and social care required (Serjeant, 2006). Such comprehensive care can lead to significantly less use of emergency departments and to reduced health care costs (Ballas, 2009).
The pain associated with a sickle cell crisis can be excruciating, and has been described as ālike hammering inside your boneā, ābeing set on fire continuouslyā and that ālabour is a piece of cake [compared] to thisā (cited in Coleman et al., 2016: 196). Pain scales, in which patients are invited to rate their pain on a scale of 1ā10, with ten representing the worst pain imaginable, are said by people living with SCD not to reflect the severity of their pain experience. The title of the painting by the Haitian artist living with SCD, Hertz Nazaire, āTen Redefinedā, suggests that even ten on the scale is insufficient to adequately describe sickle cell pain. For me, the most evocative expression of such pain is when a person with SCD reportedly spoke of their SCD pain in terms of how many years of life they would trade to be rid of their current pain.
In well-resourced settings, treatments for a sickle-cell painful crisis may include use of opioid painkillers. Treatment protocols and consensus approaches are developed by the National Institutes of Health (NIH) in the USA (NIH, 2014: 34), and the National Institute for Health and Care Excellence (NICE) in the UK (NICE, 2012). The latter recommends treating a sickle cell painful cr...
