Invasive pneumococcal disease in Alaskan children: The role of water supply and the pneumococcal conjugate vaccine (PCV)

Background - Alaska Native children (ANC) suffer disproportionately high levels of invasive pneumococcal disease (IPD), with highest rates in the Yukon-Kuskokwim region (YK) (10 times higher than the general US population). One-third of rural Alaska homes lack in-home running water.

Methods – Cases of IPD (Alaska residents with S. pneumoniae isolated from normally sterile sites) were identified through population-based laboratory surveillance from 1996-2007. The association of IPD rates with socioeconomic status and in-home running water was assessed.

Results – After national introduction of pneumococcal conjugate vaccine (PCV) in 2000, IPD rates in Alaskan children < 5 years of age declined 62% from 87 cases/100,000 (1996-2000) to 37/100,000 ( 2001-2004) and then rose to 61/100,000 (2005-2007), caused primarily by types not covered in PCV. IPD rates in ANC in YK (YK-ANC) dropped by 60%, but then rose due to non-PCV types to levels 5 and 10-fold higher than rates in non-YK-ANC and non-ANC respectively. Controlling for income and household crowding, IPD rates in YK-ANC were twice as high in villages where <10% of houses had in-home running water compared with villages where > 80% of houses had in-home running water (390cases/100,000 vs 146 /100,000, P= 0.008).

Conclusions – Despite PCV use, high IPD rates persist in Alaska, and are associated with lack of in-home running water. This effect is likely mediated through reduced water supply leading to limitations on hand-washing practices, enhancing person-to-person transmission of respiratory pathogens. Providing in-home running water to all homes may be needed to reduce Alaska's longstanding excess IPD burden.