Author: Isaac Boadu (BSc Biochemistry, MPhil Nutrition)
Department of Zoology and Environmental Biology (Parasitology and Public Health), University of Nigeria, Nsukka. (Email: [email protected])
Date: 19 June 2018
Despite the recognition of sickle cell disease (SCD) as a public health concern by the World Health Organization (WHO) and United Nations (UN) in 2006 and 2008 respectively [1, 2], the genetic disorder has still received little public attention. SCD is a chronic genetic blood disorder that occurs as a result of abnormal production of haemoglobin molecule, the oxygen-carrying substance in red blood cells (RBCs). This abnormal condition distorts the shape and properties of RBCs which affects their normal functions. The disease affects all major organs of the body mainly due to blockage of blood vessels and oxygen transport to major tissues and organs.
SCD is common with people of African or Hispanic descent with the majority of cases in sub-Saharan Africa. Globally, it is estimated that about 20-25 million people are affected with SCD with about 400,000 people born annually . Approximately 80% of these births occur in Africa especially West and Central Africa where more than half of the affected infants die before the age of 5 years. Nigeria account for the highest global burden of SCD with estimated 2 to 3% of the population affected with SCD and an estimated 150,000 annual newborns with SCD .
Difference between sickle cell carrier and sickle cell disease
What does it mean to be a carrier of sickle cell trait (SCT) and having SCD? Being a sickle cell carrier means you inherit one normal haemoglobin gene (HbA) and one defective, sickle cell gene (HbC, HbS) from each parent. Carriers do not often show symptoms of SCD but are capable of passing the sickle gene to their offspring. Couples who are carriers have 25% chance of giving birth to a normal (free from the disease) and sickle cell child as well as 50% chance of having their children being carriers of the disease.
Having SCD means inheriting the abnormal haemoglobin from both parents. This could be homozygous sickle cell (SS) disease, sickle haemoglobin C (SC) disease, sickle cell β+ thalassemia (Sβ+ thalassemia) and sickle cell β0 thalassemia (Sβ0 thalassemia) with HbSS and Sβ0 thalasemia being the most severe form of the disease. These are the predominant and commonly reported genotypes of SCD . The high prevalence of SCD in Africa is due to the high number of people being carriers of the sickle cell gene. For example, it is estimated that the incidence of SCT/carriers in Cameroon, the Democratic Republic of Congo, Gabon, Ghana, and Nigeria ranges from 20% to 30%, and in some parts of Uganda, the prevalence is as high as 45% [1, 6, 7].
How is sickle cell disease diagnosed?
Diagnosis of sickle-cell disease is based on analysis of haemoglobin. In most laboratories, sodium metabisulphite is applied to a drop of blood, which reduces the oxygen tension inducing the typical sickle-shaped red blood cells seen under the microscope. This is quick, safe and cheap. If the screening test is positive, further test such as haemoglobin electrophoresis, isoelectric focusing, and high-performance liquid chromatography (HPLC) is done to determine the genotype . Although new-born screening and early diagnosis are important to give children timely and better treatment, this is not a common practice in most African countries. Diagnosis is usually done when severe complications start occurring later in life.
Symptoms and complications of sickle cell disease
SCD is associated with increased morbidity and mortality especially in poor resourced African countries where the disease is much prevalent. Due to reduced oxygen tension and rapid break down of RBCs in SCD major organs and organs are affected or impaired. RBCs of sickle cell patients usually last up to 10 to 20 days, instead of the normal 90 to 120 days lifespan of RBCs resulting in major organ problems . Complications include incessant anaemia, intermittent pain, stroke, ocular manifestations, delayed growth and sexual maturity which may lead to impotence, priapism (prolonged and painful erection), cognitive deficit, splenomegaly, dactylitis (swollen of fingers and toes) etc. These complications often co-exist, affecting the quality of life of patients, and if untreated, often lead to death. It is estimated that about 10% of people younger than 8-10 years with SCD have strokes or brain bleeding and 24% will develop stroke by the age of 45 years [3, 9].
Management of sickle cell disease
There has been a significant improvement in the management of SCD in the last 50 years mainly in developed countries which have enhanced survival and increased life expectancy. In the 1970s, sickle cell patient‘s average life expectancy was 20 years of age . In the early 1990s, the Cooperative Study of SCD in US and other follow up study [10, 11] estimated a median life expectancy of those with sickle cell anaemia (HbSS), the most severe form of the disease, to be 42 years of age for males and 48 years of age for females. A high proportion (93.9%) of children diagnosed with SCD in the study survived to adulthood. In Jamaica, life expectancy stands at 53 and 58.5 years for men and women, respectively . Contrary to this, in Africa, most children die before their 5th birthday and most cases of SCD are often undiagnosed .
Effective management of SCD revolves around genetic counselling, neonatal screening and early diagnosis; prophylaxis with immunizations; providing anti-malarial medication, adequate hydration and nutrition, and prompt management of complications with the provision of analgesics and routine folate supplementation. To date, Bone Marrow Transplantation (BMT) is the only confirmed cure for SCD , but this is an expensive treatment and may not be feasible as a public health approach in low resource countries . In Sub-Saharan Africa, a recent report indicates that Ghana is the only country known to have started BMT as a curative measure but this is expensive hence sustainability is questionable without financial support. Cost stands at $15000 and $20,000 for a full-match donor and partial donor respectively .
World Sickle Cell Day
In 2008, World Sickle Cell Day was initiated by the United Nations General Assembly with the main aim of increasing awareness of SCD and its cure. This has been celebrated every year on 19th of June all over the world to cover fast awareness campaign, curable activities, early diagnosis and management. Various themes have been adopted by the celebration including ‘Know your sickle cell status’ (2013), ‘Break the Silence on Sickle Cell Disorder’ ( 2014), ‘For sickle cell to stop being ignored you must STOP YOUR SILENCE and SHARE YOUR TRUTH’ (2015), ‘Exhibit courage and address ineffective areas of support’ (2016), ‘Break the Sickle Cycle’ (2017) etc. . These celebrations themes and other global activities have partly helped raised awareness of SCD but more efforts are needed to expand the scope of understanding and knowledge level of people particularly in the Africa populace.
Conclusion and recommendations
It is imperative to mention that SCD not only brings intermittent pain and stigmatization among sufferers but psychosocial, emotional and financial burden to caregivers and parents. It is advocated that prospective partners know their sickling status in order to make informed choices and reproductive decisions regarding the genetic disorder.
To address the global prevalence of SCD, there is the need to intensify public education through mass media campaigns (Television, radio, newspapers, magazines etc.), schools (in the form of debate, seminars etc), churches and other community gatherings to increase understanding and knowledge level of SCD. Boadu and Addoah  have stressed the importance of using these platforms as an effective media for raising public awareness and increasing knowledge.
SCD is not a death sentence, knowing your status is as important as not having SCD as well as saving the suffering of an innocent child.
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