For the first time in the country, a national baseline prevalence survey using a well-defined sampling design such as a stratified two-step systematic cluster sampling was conducted in 2005 to 2008. The purpose of the survey was to stratify the provinces according to prevalence of schistosomiasis such as high, moderate, and low prevalence which in turn would be used as basis for the intervention program to be implemented. The national survey was divided into four phases. Results of the first two phases conducted in Mindanao and the Visayas were published in 2008. Data from the last two phases showed three provinces with prevalence rates higher than endemic provinces surveyed in the first two phases thus changing the overall ranking of endemic provinces at the national level. Age and sex distribution of schistosomiasis remained the same in Luzon and Maguindanao. Soil-transmitted and food-borne helminthes were also recorded in these surveys. This paper deals with the results of the last 2 phases done in Luzon and Maguindanao and integrates all four phases in the discussion. 1. Introduction Schistosomiasis is a water-borne trematode infection that is endemic in 76 countries 46 of which are in Africa. About 207？M people are infected with 120？M people showing symptoms and 20？M severely ill [1]. In the Philippines, the disease is endemic in 28 out of 81 provinces distributed in 12 regions with a total population of 12？M exposed to the disease [2]. The infection affects almost the whole of the Mindanao region, the eastern part of the Visayas, and a few provinces in Luzon [3]. Surveys on a national scale have been scarce in the past. Most of these surveys were conducted in endemic areas using active and passive case finding. The lack of a well-defined study design resulted in overrepresentation or underrepresentation in the outcome of these surveys (Philippine Department of Health, unpublished data). Mass treatment using praziquantel has been a mainstay in the control program for schistosomiasis. The subsequent reduction in prevalence in many endemic areas resulting from mass treatment has encouraged the Philippine Department of Health to pursue further its goal in schistosomiasis control such as to press further down the prevalence in some areas and to even push for elimination in some areas. Streamlining of the program would be based on stratification of provinces into high prevalence, moderate prevalence, and low prevalence status. Accurate stratification is dependent on a baseline prevalence survey using an appropriate sampling technique that would generate
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