An article published Online First and in a future edition of The Lancet reports that the organisms causing bacterial infections in African children with sickle-cell anaemia are the same as those in developed countries. Vaccination against these bacterial infections could considerably improve survival in these children. Vaccines are already available in developed nations. The article is the work of Dr Thomas N Williams, KEMRI/Wellcome Trust Programme, Kilifi, Kenya, and colleagues across Africa and the UK.

Before the diagnosis can be made, more than 90 percent of children with sickle-cell anaemia die in sub-Saharan Africa. The prognosis of patients born with sickle-cell anaemia in developed countries has significantly improved with the introduction of penicillin prophylaxis and immunisation with conjugate vaccines directed against S pneumonia and H influenzae type b. Almost certainly, bacterial sepsis plays an important role although the causes of death are poorly documented. Existing evidence has suggested that the variety of organisms causing invasive bacterial disease in African patients with sickle-cell anaemia might be different from those in developed countries. Researchers evaluated the risk of invasive bacterial diseases in children with sickle-cell anaemia. They examined the blood cultures from all children younger than fourteen years. The young patients were admitted from within a defined study area to Kilifi District Hospital between Aug 1, 1998, and March 31, 2008. The children who had bacteraemia were defined as cases.

In 38,441 admissions, the researchers detected 2,157 episodes of bacteraemia (6%). From these children who had bacteraemia, 1,749 were typed for sickle-cell anaemia (81%). From this group, 108 children tested positive (6%). The organisms most commonly isolated from children with sickle-cell anaemia were:

• Streptococcus pneumonia (44 of 108 isolates; 41%)
• non-typhi Salmonellaspecies (19 of 108; 18%)
• Haemophilus influenza type b (13 of 108; 12%)
• Acinetobacterspecies (7 of 108; 7%)
• Escherichia coli (7 of 108; 7%)

Children with sickle-cell anaemia were twenty six times more likely to have an invasive bacterial infection than those without. The strongest associations for specific bacteria were:

• S pneumonia (33 times more likely for children with sickle-cell anaemia)
• certain types of Salmonella species (36 times more likely)
• H influenza type b (28 times more likely)

The authors explain: "Overall, more than 10% of episodes of pneumococcal bacteraemia in our study occurred in children with sickle-cell anaemia, three quarters of which were of serotypes that are represented in the licensed ten-valent pneumococcal conjugate vaccine. Although the introduction of pneumococcal conjugate vaccine into routine immunisation schedules in Africa will be of benefit to all, it is likely to be particularly beneficial for children with sickle-cell anaemia."

They write in conclusion: "The organisms causing bacteraemia in African children with sickle-cell anaemia are the same as those in developed countries. Introduction of conjugate vaccines against S pneumoniae and H influenzae into the childhood immunisation schedules of African countries could substantially affect survival of children with sickle-cell anaemia."

In an associated comment, Dr Jane Hankins and Dr Russell E Ware, of the St Jude Children's Research Hospital, Memphis, TN, USA, remark: "Whether in the Americas, Europe, or Africa, sickle-cell disease remains an affliction affecting millions of persons, but the lessons are clear. The key to reducing morbidity and mortality involves early identification through screening, early antibiotic prophylaxis, education about disease complications, and appropriate immunisations against bacterial pathogens, especially S pneumoniae. When these ounces of prevention are put into place, we make important strides toward a pound of improvement and eventual cure."

"Bacteraemia in Kenyan children with sickle-cell anaemia: a retrospective cohort and case-control study"
Thomas N Williams, Sophie Uyoga, Alex Macharia, Carolyne Ndila, Charlotte F McAuley, Daniel H Opi, Salim Mwarumba, Julie Makani, Albert Komba, Moses N Ndiritu, Shahnaaz K Sharif, Kevin Marsh, James A Berkley, J Anthony G Scott
DOI: 10.1016/S0140-6736(09)61374-X
The Lancet

Stephanie Brunner (B.A.)