High burden of invasive Streptococcus agalactiae disease in South African infants.

The epidemiology of invasive Streptococcus agalactiae (GBS) disease was evaluated in South African children. Records of 208/220 children in whom GBS was isolated between January 1997 and December 1999 were reviewed. These included 63%, 31.7% and 5.3% children with early- (EOD, <7 days of age), late- (LOD, age 7-90 days) and childhood-onset disease (COD, age >90 days), respectively. The overall burden of EOD and LOD were 2.06 and 1/1000 live births, respectively. The overall mortality was 19.8% and 13.6% for infants with EOD and LOD, respectively. Risk factors for mortality in infants with EOD and LOD included septic shock (82.1% vs 1.9%), prematurity (35.2% vs 9.6%), low birthweight (29.2% vs 11.0%) and a leucocyte count <5000/mm(3) (43.5% vs 18.6%). Eight (72.7%) of 11 children with COD had an immunosuppressive, predisposing cause for invasive bacterial disease. In infants with EOD and LOD, serotype III isolates caused 49.2% and 75.7% of disease, respectively, and, together with serotype Ia isolates, caused 78.9% and 100% of invasive disease, respectively. Invasive GBS disease is common in South African infants and current strategies aimed at reducing the burden of the disease should be reconsidered.