Age- and serotype-specific pediatric invasive pneumococcal disease: insights from systematic surveillance in Santiago, Chile, 1994--2007.

BACKGROUND

We monitored pediatric invasive pneumococcal disease (IPD) in Santiago, Chile, from 1994 to 2007.

METHODS

Three related data sets were generated: (1) IPD cases requiring hospitalization, 1994--2007; (2) cases of bacteremia detected among febrile patients aged 0-35 months seen in emergency departments, 2000--2007; and (3) nasopharyngeal carriage of pneumococcal serotypes, determined from repetitive culturing, among 524 newborns followed up through age 23 months.

RESULTS

Of 2369 IPD cases requiring hospitalization, 1878 (79.3%) occurred in those aged 0-59 months, and 1200 (50.7%) occurred in those aged 6-35 months. Among infants aged 0-5 months, meningitis and sepsis comprised 48.4% of all IPD cases (serotype 5 predominated); among those 6-35 months old, 522 (43.5%) of 1200 cases were bacteremic pneumonia (serotype 14 predominated). Serotype 1 peritonitis was common among 5-14-year-old girls. Meningitis and sepsis exhibited high case fatality rates (14%-29%) among all ages. Remarkably, 34 (28.8%) of 118 children with sepsis died, versus 1 fatality (0.4%) among 276 children hospitalized with bacteremia without a focus (P < .001, Fisher's exact test). Serotype 5 was significantly more common among hospitalized patients < 36 months of age, whereas serotype 18C was overrepresented among ambulatory patients. The annual incidence of serotype 14 was stable; those of serotypes 1 and 5 fluctuated markedly. Serotypes 14, 5, and 1 were overrepresented among invasive compared with nasopharyngeal isolates.

CONCLUSIONS

Clinical syndromes of IPD and predominant serotypes vary with age.