Children in developing countries are at far greater risk of contracting potentially lethal bacterial infections than was previously thought, new research reveals today.

The authors of this latest study say it provides further support for the immediate introduction of effective vaccines against invasive bacterial infections, which are believed to cause a large proportion of the estimated 4.4m deaths a year among children living in sub-Saharan Africa.

The research, which was supported by the Wellcome- KEMRI Research Programme* and is published in this week’s (February 11th) edition of The Lancet, looked at bacteraemia – blood infection - in nearly 1100 youngsters aged five and under who attended the outpatients department of Kilifi Hospital in Kenya. The results suggest that twice as many children with bacteraemia visit the hospital than was previously estimated.

But Dr Andrew Brent, who led the project while on a Wellcome Trust visitors grant, believes that the number of children living in the local community who suffer from the problem may be even bigger.

“Many sick children in Kilifi District never even make it to hospital because they live too far away or cannot afford treatment,” he said. “In 2003 only about a third of childhood deaths registered in the district occurred in hospital. That’s one of the reasons why we think it is likely there are many more undetected cases of bacteraemia.

“And this is just the tip of the iceberg of serious bacterial infections. Common diseases like pneumonia and meningitis often do not have detectable bacteria in the blood, even when you know what to look for.”

According to Dr Brent bacteraemia can only be detected by a lengthy process of taking and incubating a blood sample in clean conditions. After a few days bacteria may be detected, and these have to be analysed by trained staff. This is impossible in most resource-starved hospitals in the developing world.

During the study – which confirmed that patients may have bacteraemia even though they do not at first appear sick - Dr Brent and his team made follow-up home visits to children who had been treated as out-patients, but who were later found to have the infection. The condition of several of these children had deteriorated leaving them needing hospital admission.

Overall, Dr Brent and colleagues estimate that six per cent of children in Kilifi district will attend hospital with bacteraemia by the age of five, and one in six of these children will die.

“Many of these deaths are potentially preventable,” he added. “Half of all cases of bacteraemia in this study were caused by a bacterium called ‘pneumococcus’, for which a vaccine is available, and other studies in Africa have shown that the this is very effective. Our study provides further evidence that pneumococcal infections are common and serious, and emphasizes the urgent need for vaccination of all children who are at risk.”