Sickle cell disease is an epidemic in West Africa and can be found in one in four people. It occurs due to an abnormality in haemoglobin, the protein that holds the oxygen in red blood cells. When this abnormality occurs, what results is the haemoglobin type S, which is an abnormal type. T
The normal haemoglobin is type A and people without sickle cell disease or trait have two copies (Hb AA). People with sickle cell disease have two copies of haemoglobin S (Hb SS) while people with the trait have only one copy (Hb AS). The genes that cause the production of haemoglobin S can be transmitted from parents to their children. The high prevalence of the sickle cell gene in West Africa is due to the high prevalence of malaria. Red blood cells with haemoglobin S are unfavourable for malaria parasites to inhabit.
The types of haemoglobin a person makes in the red blood cells depend on what hemoglobin genes are inherited from his parents. If one parent has sickle-cell anaemia (SS) and the other has sickle-cell trait (AS), there is a 50% chance of a child's having sickle-cell disease (SS) and a 50% chance of a child's having sickle-cell trait (AS). When both parents have sickle-cell trait (AS), a child has a 25% chance (1 of 4) of sickle-cell anaemia (SS), and if only one parent has a sickle-cell trait (AS), each child they have has a 50% chance of having the trait.
The strong advice is that people who have sickle cell genes (HbSS or Hb AS) have children with people who do not carry the trait (AA genotype) so that their children may have AS or AA genotypes.
What causes sickle cell disease manifestation is the deformation of red blood cells with haemoglobin S in conditions with reduced oxygen. The red blood cells change structure from a pliant disc to a rigid sickle shape. The rigid sickle-shaped cells are notorious for clogging up small blood vessels, not carrying enough oxygen and breaking apart easily. This causes the infamous sickle cell crises which has taken numerous lives. Sickle cell disease is different from sickle cell trait. A person with sickle cell disease is prone to sickle cell crises, anaemia, jaundice, stroke, gallstones, damage to organs and certain bones, and wounds that heal poorly. They may live a normal life with very few crises.
Sickle cell crises are of two types, both are potentially fatal. The vaso-occlusive crises involve a lot of pain to limbs, chest, abdomen and even genitals (penis or clitoris). Anaemic crises involve a drastic fall in blood levels. Both crises are caused by triggers which predispose cells to sickling. These triggers include:
- Extremes of cold and heat,
- Obstetric delivery,
- Rigorous exercise and,
- Any form of intense stress.
The presence of non-sickling haemoglobin: HbF, HbA prevents sickling and crisis. This is why people with the sickle-cell trait usually do not have crisis and babies who always have the fetal haemoglobin HbF, do not have problems associated with sickle cell disease until about six months of age when haemoglobin F disappears from the blood. People with sickle cell trait have been considered fortunate to be protected against malaria by the HbS and against sickling by HbA, however recent events of sudden death in athletes with the sickle-cell trait undergoing vigorous exercise has put the possibility of significant sickling still occurring in sickle-cell carriers.
To prevent crises, sickle cell disease patients are advised to make conscious efforts to always stay hydrated, prevent exposure to excessive heat or cold and not partake in vigorous exercise. Doctors advise patients with sickle-cell disease to prevent malaria and other infections, treat infections promptly, see a doctor when they have a fever or cough and take folic acid every day. Vaccines against Pneumococcal, Haemophilus influenza and Hepatitis vaccine can help prevent some common infections that may cause crises. Special care should be given to pregnant women, who are to attend antenatal clinics religiously and adhere to the doctors’ advice. Athletes are advised to know their genotypes and those with sickle-cell trait are advised to be careful when doing vigorous exercise, including ensuring adequate hydration and rest.
Some scientists have attempted to explain the Abiku and Ogbanje myth with the sickle cell disease. Abiku and Ogbanje refer to people who are believed to undergo a repeated sequence of birth and death, being born to the same parents each time. This has been traditionally attributed to spirits beings with the supernatural power to will their births and deaths. However, it is interesting to note that in contemporary times, families with both parents known to have sickle-cell trait have experienced the loss of children in a similar way. Also, there has been reduced mention of Abiku in recent times since diagnosis and treatment of sickle cell disease and crises became possible. This does not mean children with sickle-cell disease are Abiku or Ogbanje, rather it questions if the Abiku and Ogbanje children of the past were children with sickle-cell disease dying due to lack of adequate medical care and diagnosis.