Controlling schistosomiasis in Southeast Asia: a tale of two countries.

An overview of schistosomiasis control in the People's Republic of China and the Philippines is presented. Whilst the Chinese have managed to reduce the number of Schistosoma japonicum infections from an estimated 11.6 million to well below 1 million since 1950, the corresponding drop in the Philippines is less pronounced: from 700,000 in 1975 to currently 560,000. However, these figures should be seen in the context of the population growth, which approximately doubled the Chinese population over the past 60 years (from 557 million to 1.3 billion) whereas the number of Filipinos during the same time more than quadrupled (from 21 to 93 million). The Philippine progress should also be judged against the backdrop of regional political instability combined with strong socio-ecological dynamics. Although substantial improvements have been achieved in both countries, compliance is waning in people repeatedly given praziquantel with or without prior diagnosis and this problem will not be reversed without sustained vigilance. In addition, the lower rates of excreted eggs per gram of stool in the new endemic situation characterised by widespread, low-intensity infections influence the accuracy of prevalence assessments negatively. Remaining pockets of high transmission further complicate the situation. Maintaining that advances in schistosomiasis control critically depend on technical progress, we discuss the problems currently facing control programmes from the viewpoint of what research can actually contribute at this stage of disease control. The need for flexible control approaches is emphasised and more sensitive diagnostics is highlighted. Above all, it is argued that strengthened, innovative surveillance approaches are called for if elimination of the disease is to succeed.