Animal Waste, Water Quality and Human Health

296Animal Waste, Water Quality and Human Healthwas voted down due to lack of political will, vested interests by industry, andinformation manipulation (Hurlimann & Dolnicar 2009).8.4 EXAMPLES OF EXPOSURE INTERVENTIONSThe remainder of this section demonstrates the potential for positive impact,improved water quality, and the protection of public health from remediationinitiatives. In some instances these actions were derived from the distribution offaecal indicator organisms and pathogens in the environment frequently inresponse to transport mechanisms such as the influence of environmentalconditions and riverine/coastal processes (see: Chapter 5) (Haack et al. 2003,Touron et al. 2007). Other times intervention programmes have been developedbased on knowledge of the life cycle or the clinical disease state (see: Chapter 2).In either instance, the measures often resulted in the revamping of traditionalcultural or agricultural practices.8.4.1 Schistosoma japonicum (schistosomiasis)Schistosoma spp. are trematode parasites with a lifecycle of adult worms living inthe veins of mammals and birds and larval stages in the aquatic environment withan obligatory passage through aquatic or amphibious snails. The disease they cause(schistosomiasis) is of significant global public health importance: and estimated779 million people are at risk globally (Steinmann et al. 2006). In East AsiaSchistosoma japonicum is distributed in China, the Philippines and Indonesia,and closely associated with irrigated rice production systems. Excreta frominfected humans and other infected mammals, containing parasitic eggs, arereleased into surface water. The parasitic eggs in turn infect intermediate hosts(in the case of S. japonicum: the amphibious snail Oncomenalia hupensisquadrasi) (Carabin et al. 2005, Riley et al. 2005). Schistosomiasis in humansoccurs when the larvae released from the intermediate host penetrate the skin ofpersons washing, bathing, or participating in recreational activities (wading,swimming, or rafting) in contaminated water (MMWR 1993, Schwartz et al.2005). The nature of disease transmission results in high incidence of infectionor exposure risk in communities where humans are in close proximity to alivestock or other mammalian source. Multiple challenges exist with respect toexposure interventions: case detection and treatment, mass drug treatment,installation/use of properly built latrines, eradication of the intermediate host, orprevention of contact with contaminated water (Febles 1964, Yi-Xin &Manderson 2005, Tallo et al. 2008). The eradication of the intermediate host