[Prevalence of Chagas disease among blood donors in Piauí State, Brazil, from 2004 to 2013].

Despite the decline in prevalence of Chagas disease in Brazil, the Northeast region of the country has favorable conditions for its resurgence. The study aimed to analyze positive Chagas disease serology rates among blood donors in Piauí State from 2004 to 2013. Prevalence of positive Chagas disease serology in blood donor screening was 1%, ranging from 0.4% in the Uruçuí Regional Health District to 2.4% in the São Raimundo Nonato Regional Health District. Of the state's 220 municipalities, 58.6% reported cases. Only 34.5% of the positive samples in screening were referred for complementary tests, and 84.4% of these showed negative results. Our findings suggest the possibility of persistent vector-borne transmission in areas of Piauí State and the need for measures to improve complementary testing in positive cases detected by screening.