Prof. Xiao-Nong Zhou, National Institute of Parasitic Diseases, China CDC
The road map for eliminating neglected tropical diseases (NTDs) issued by World Health Organization in 2012 has persuaded the global community to join together to find solutions. NTDs are mainly prevalent in poor and rural areas of developing countries. Among 17 parasitic and bacterial infections, eight are helminthiases including soil-transmitted helminthiases (STHs) (like ascariasis, hookworm infection, trichuriasis), food-borne trematodes, lymphatic filariasis, onchocerciasis, dracunculiasis, cysticercosis, echinococcosis, and schistosomiasis, according to a 2010 WHO report. An estimated 1 billion people are infected with one or more helminth species, mainly in sub-Saharan Africa, Asia, and the Americas (Hotez et al., 2007; 2008).
In the People’s Republic of China (P.R. China), NTDs are one of the most prevalent infectious diseases, with more than 100 pathogens recorded to infect humans. In the 1950s, the beginning of the P.R. China, the most heavily epidemic NTDs were schistosomiasis, malaria, lymphatic filariasis, hookworm, and leishmaniasis that affected local people’s health as well as social-economic development. Due to great efforts by government leadership, professional guidance and community involvement, NTDs have declined significantly with the increase in economic development in China. For example, lymphatic filariasis was eliminated in China by 2007, and the national malaria elimination program has been launched with its goal to eliminate malaria by 2020. The working plan for national schistosomiasis elimination by 2020 is under development in P.R. China. The prevalence of soil-transmitted helminthiasis, like hookworm, has been reduced to under 20%. The leishmaniasis has been localized in northwestern China with less than 400 total of reported cases annually.
The new top five NTDs are schistosomiasis, malaria, echinococcosis, soil-transmitted helminthiasis and food-borne tremedotes, and already these infections have been significantly reduced. However, the prevalence of food-borne tremedotes is increasing with new outbreaks reported every year. Therefore, China has had success and has learned many lessons that could help other developing countries reduce or eliminate tropical diseases.
For example, schistosomiasis japonica, which has been prevalent in P.R. China over 2000 years, was recognized as an important infectious disease and the national schistosomiasis control program was initiated in the 1950s. Great achievements have been gained. Five out of 12 endemic provinces have reached the criteria of elimination, and three provinces have reached the criteria of transmission- controlled. The remaining four provinces will reach the criteria of transmission-controlled by 2015. The lessons of political will, sustained financial and technical support, and an integrated approach readily adapted to different eco-epidemiological settings and fine-tuned over time have been learned to substantially reduce the burden of schistosomiasis.
In addition to the integrated control strategy of schistosomiasis developed recently in P.R. China which transfers the morbidity control into transmission control, more technical developments in tropical diseases have accelerated the progress of the national control program significantly. These include novel chemical molluscicides, rapid diagnostics, new development of drugs, as well as new tools to monitor the transmission of tropical diseases. All of those control strategies and novel tools/products are ready to be used in the transition phase from control into elimination programs in other regions although the various species of pathogens are different in terms of biology and morbidity. It is promising for Chinese scientists to work together with local professionals in other regions to tailor the Chinese control strategy and experience into local settings, in order to achieve the goal of transmission-control leading to elimination of tropical diseases.
One of the biggest contributions toward the achieving disease control/elimination is the adoption of control/elimination strategy and socio-economic development, along with the achievement of implementation research to provide the sound information to the decision makers. Based on the current profile of NTDs in P.R.China, the priorities of technology development used for the control/elimination of NTDs will focus on documentation and development of health metrics that are useful in practice, support research on the impact of social determinants and economic issues on the epidemiology of NTDs, promote GIS and remote-sensing techniques to study climate change and other applications, encouragement of the study of genetics and the immune responses against parasites to better understand the pathology for the development of vaccine for NTDs, improvement and standardization of the diagnostic capabilities including development of new products, equipment and techniques, and implementation research related to control strategies. With more initiatives like the national NTDs elimination program, surveillance and response that take into account the One World-One Health approach to integrate and streamline common surveillance activities are recommended as a first line strategy. In particular, in developing countries with limited resources for disease surveillance and response activities, the surveillance response systems should be strengthened along with the improvement of the health system.