A National Baseline Prevalence Survey of Schistosomiasis in the Philippines Using Stratified Two-Step Systematic Cluster Sampling Design

Abstract

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.

Geographical distribution of human Schistosoma japonicum infection in The Philippines: tools to support disease control and further elimination

“…We used S. japonicum infection data collected during the most recent national schistosomiasis surveys conducted in 2008 (Leonardo et al, 2008, 2012) (Supplementary Data S1). The surveys were divided into four phases: phase 1 for Mindanao (excluding Maguindanao), phase 2 for the Visayas, phase 3 for Luzon and phase 4 for Maguindanao.…”

“…The most recent national parasite survey in The Philippines concluded that S. japonicum infection was endemic in 28 of the 80 provinces of the country (Leonardo et al, 2008, 2012). An estimated 6.7 million people are considered at risk, with 1.8 million estimated to be infected (Leonardo et al, 2002).…”

“…However, recent experience in Western Samar has shown very low acceptance of MDA by the population, despite community mobilization activities, with an average coverage of 48.3% in 50 villages, and values as low as 15.8% (Tallo et al, 2008). This has likely contributed to the prevalence of infection still being reported in some communities to be as high as 65% (Leonardo et al, 2008, 2012). …”

“…The most up-to-date schistosomiasis prevalence data from The Philippines, and data from Western Samar, have shown considerable variability between communities (Tarafder et al, 2006; Leonardo et al, 2008, 2012). Spatial clustering of schistosome infections in high-prevalence communities is a well-described phenomenon (Clements et al, 2006).…”

Schistosomiasis mass drug administration in the Philippines: lessons learnt and the global implications

“…Approximately 12 million people living in 28 endemic provinces located in 12 different regions of the country are at risk of infection ( Fig. 2) [19,20]. Overall, a total of 190 municipalities and 20 cities are affected by the infection.…”