Pneumococcal infections and sickle cell disease in Africa: does absence of evidence imply evidence of absence?

Abstract

Sickle cell disease (SCD) compromises host immune defence and predisposes to infections from several encapsulated bacteria, viruses and parasites. While penicillin prophylaxis and pneumococcal vaccination are established routine care in developed countries, such preventive measures are poorly structured or non-existent in most malaria-endemic, developing country settings. In fact, the role of pneumcoccal infections has been brought into question, based on available data. The role of invasive pneumococcal disease in child mortality has now been established from population-based studies in such settings. Thus, it may be unsafe to assume that children with SCD are less susceptible. Whether malaria endemicity increases susceptibility to other encapsulated bacteria such as salmonella infections is a critical but unanswered question that will inform the development of appropriate preventive measure policies in this setting. Research to clearly define the leading cause of infection-related morbidity and mortality in SCD in Africa should be encouraged.

Morbidity and Mortality in Anemia

“…In Africa, available mortality data are sporadic and incomplete. Many children are not diagnosed, especially in rural areas, and death is often attributed to malaria or other comorbid conditions (65). The mortality rates in SCA amongst a hospital-based cohort in Tanzania (66) was 1.9 per 100 PYO which is similar to 3 per 100 PYO reported from the USA before use of penicillin prophylaxis (67), with the highest incidence of death was in the first 5 years of life.…”

“…Evidence from previous research suggests that infection is the most likely cause of death in this period, with the proportion of deaths from infection reported to be 50% in the USA (60, 68), 28% in Jamaica (69) and 20% in Dallas (63). The prevention of pneumococcal infection with penicillin and the introduction of pneumococcal conjugate vaccine has been shown to be effective in reducing mortality (70) with improved survival rates of 84% in Jamaica (69), 86% by 18 years in Dallas (64) and 99% in London (65). One review reported 42% reduction in mortality in SCA in USA, 0 to 3 years old, between two eras, 1995-1998 and 1999-2002 (71).…”

“…One review reported 42% reduction in mortality in SCA in USA, 0 to 3 years old, between two eras, 1995-1998 and 1999-2002 (71). There is compelling justification for implementation of these interventions in Africa to prevent deaths due to infections (65,66). Sudden death is not uncommon among SCA patients.…”

High mortality from Plasmodium falciparum malaria in children living with sickle cell anemia on the coast of Kenya

“…21 In Africa, however, where more than 230 000 affected children are born each year, 4 the picture is very different. The majority of these children die in early life before the diagnosis of SCA has ever been established, 3,5,8,22 such that currently SCA is responsible for more than 6% of all deaths in African children younger than 5 years. 4 This proportion is set to rise as governments strive to meet their Millennium Development Goals and all-cause under-5 mortality begins to fall.…”

“…Nevertheless, surprisingly little research has been conducted in Africa, [1][2][3] where more than 230 000 children with SCA, approximately 80% of the global burden, are born every year. 4 Although malaria is widely considered a major cause of death in African children with SCA, 1,[5][6][7] this assumption is supported by surprisingly few data.…”