Monitoring the impact of a mebendazole mass drug administration initiative for soil-transmitted helminthiasis (STH) control in the Western Visayas Region of the Philippines from 2007 through 2011

School-aged children in tropical developing countries carry the highest burden of soil-transmitted helminth (STH) infections in the world. The Western Visayas region of the Philippines continues to struggle with this as a major public health issue in both private and public schools. The War on Worms-Western Visayas approach was launched in 2007 with school-based mass drug administration (MDA) as one of the strategies to control morbidity from STH in support of the Department of Health – Integrated Helminth Control Program. This study aimed to determine trends in prevalence and intensity of STH infections as well as to assess related morbidity and program sustainability through 2011. A cross-sectional parasitologic survey was conducted on three independent samples of Grade 3 students in 2007, 2009, and 2011. Supporting aggregate data were obtained for MDA coverage, National Achievement Test mean percentage scores, and nutritional status. Tests for trend were utilized to detect changes in prevalence over time, with a particular emphasis on trends seen between 2009 and 2011. The initial impact of the program was robust as cumulative prevalence, infection intensities, and parasite densities were all reduced four years following the launch. However, subsequent and significant increases in each were found from 2009 until 2011. These results implicate issues with program sustainability, despite consistent MDA, and existing frameworks for environmental sanitation, hygiene, and education.