Marked decline in malaria prevalence among pregnant women and their offspring from 1996 to 2010 on the south Kenyan Coast.

Expanded malaria control in Kenya since the early 2000s has resulted in marked reduction in hospital admissions for malaria; however, no studies have reported changes in malaria infection rates in the same population over this period. Randomly selected archived blood samples from four cohorts of pregnant women and their children from 1996 to 2010 in Kwale District, Coast Province, Kenya, were examined for Plasmodium falciparum (Pf), P. malariae, P. ovale, and Plasmodium vivax by quantitative polymerase chain reaction (PCR) and microscopy. Maternal delivery Pf prevalence by PCR declined from 40% in 2000-2005 to 1% in 2009-2010, concordant with increased bed net and malaria chemoprophylaxis use. Individual risk of Pf infection in children from birth to 3 years in serial longitudinal cohort studies declined from almost 100% in 1996-1999 to 15% in 2006-2010. Declines in P. malariae and P. ovale infections rates were also observed. These results show a profound reduction in malaria transmission in coastal Kenya.