Up to a million children die every year from pneumococcal infections, mainly as a result of pneumonia or meningitis. (See a recent TropIKA.net news story.) In the developed world, vaccination with pneumococcal conjugate vaccine (PCVs) is now widespread and cases of the disease usually receive effective treatment. Nine-eight per cent of pneumococcal deaths occur in developing countries. The need for vaccination programmes in those countries is abundantly clear.
Are people with sickle cell disease (an inherited disorder that is extremely common in Africans) at particular risk of contracting pneumococcal disease? The condition is known to cause an immune deficit so it seems likely to be a risk factor. Those people with SCD who live in developed countries receive prophylactic treatment with penicillin, as well as pneumococcal vaccination, and this is considered to be a major factor in the reduction of morbidity and mortality in SCD patients in these countries.
People with SCD in developing countries would, therefore seem, to be priority targets for pneumococcal vaccination programmes and they should also be receiving penicillin prophylaxis. However, this has been challenged because there are no published studies proving that children in Africa with SCD are particularly at risk of pneumococcal disease. Writing in Archives of Disease in Childhood, Stephen Obaro of Michigan State University argues that absence of evidence of this risk is not evidence of absence.
In his extensive review article (1) Dr Obaro notes the lack of reliable data as to the causes of morbidity and mortality in people with SCD living in Africa. He calls for further research into this issue. However, he believes that, “It is unlikely that African children with SCD will be at less risk from IPD [invasive pneumococcal disease] than children without this condition”. Given their compromised immune systems he argues that a full range of prophylactic measures is required for these children.
1. Obaro S (2009). Pneumococcal Disease in Sickle Cell Disease in Africa: Does Absence of Evidence Imply Evidence of Absence? Arch Dis Child; May 3.