Sickle-cell anemia is common in population in Saharan Africa and their descendants from parts of the world. Sickle-cell disease can occur in any individual of any race or ethnicity across the globe."Sickle-cell anemia" is a specific form of sickle-cell disease caused by a homozygous mutation forming Hgb S. Other forms of sickle-cell disease include sickle-haemoglobin C disease,sickle beta-plus-thalassemia,sickle beta-zero-thalassemia and hemoglobin ss causesd by heterozygous genes (Orah , 2000)..The origin of the mutation that led to the sickle cell gene was initially thought to be in the Arabian region spreading to Asia and Africa. It is now confirmed from evaluation of chromosome structures that there should have been at least four independent mutational events spanning over 70000 to 150000 years, three in Africa and a fourth in either Saudi Arabia or central India.The evolution of sickle-cell anaemia is understood and explained as an example of Baldwinian phylogeny whereby humans modify their environment and thus change the selective pressures.
Patients with sickle cell anaemia exhibit anaemia with typical hemoglobin levels of 6-9 g/dl. Evaluation of reticulocytes reflects new red blood cells replacing the rapidly destroyed older cells because of a drastic reduction in red blood cell life span. Reticulocytes are immature red blood cells, typically comprising about 1% of the red cells in the human body. Reticulocytes develop and mature in the bone marrow and then circulate for about a day in the blood stream before developing into mature red blood cells.Reticulocytes do not have a nucleus. They are called reticulocytes because of a reticular or mesh-like network of ribosomal RNA.Reticulocytes appear slightly bluer than other red cells when looked at with the normal Romanowsky staining procedure. Evaluation of the white blood cell and platlet counts indicate vaso-occlusion( Kinney et al.1999).
Complications of Sickle cell Anemia
Most patients with sickle cell disease suffer intensely painful episodes called vaso-occlusive crises The frequency, severity, and duration of these crises vary tremendously. Such painful crises are treated with hydration and analgesics.A vaso-occlusive crisis is a condition caused by sickle-shaped red blood cells that obstruct capillaries and restrict bloodflow to an organ often resulting in pain,ischemia and and organ damage. The Spleen is frequently affected due to narrow blood vessels and its metabolic function in clearing defective red blood cells. It is usually in infracted state before even the end of childhood in sickle-cell anemia cases(Orah , 2000). This causes autosplenectomy.Autosplenectomy occurs when the spleen is damaged to such an extent that it is non-functioning and hence equivalent to the spleen having been surgically removed .This further increases the risk of infection from encapsulated organisms. Prophylactic antibiotics and vaccinations are recommended for those with such asplenia.Asplenia refers to the absence of normal spleen function and is associated with infection risks.Asplenia increases the risk of septicaemia especially due to infection with Pneumococcus,Haemophilus and Meningococcal bacterial species which can kill