Animal Waste, Water Quality and Human Health

Assessing the importance of zoonotic waterborne pathogens 37Infection is very light but it is important to note that a carabao produces 50–60 kgof stool per day (Wu et al. 2010) and there are around 1 million carabaos (usedin rice farming) in the endemic areas of the country. This finding suggeststhat carabaos are also important in the transmission of S. japonicum in thePhilippines.The fact that animal reservoir hosts are considered to play an integral role intransmission of S. japonicum to one another and humans, has led to newstrategies for control of S. japonicum infections. Aside from chemotherapy inhumans, basic and applied research is being directed at the use of chemotherapyand vaccination in animals to eliminate the reservoir for human transmission(Wan et al. 1998, McGarvey et al. 1999, Shi et al. 1998; McManus et al. 1998,Lin et al. 1998, Nara et al. 1998, Zhou et al. 1998).In the Philippines, dogs are also a potential target of control programmes(Rudge et al. 2008). Dogs are owned by a high proportion of households inrural communities and are usually permitted to roam freely, often entering orfeeding in other households as they scavenge for food. Such behaviours mightbe expected to facilitate environmental contamination by S. japonicum-infecteddogs in areas where there is an overlap with human activities. Furthermore,census data from study villages in the Philippines, show a mean number of104.9 dogs per village, which is almost three times that of carabao(36.2/village) and somewhat greater than the number of cats (90.4/village)(Rudge et al. 2008).Wild rats should also be a target of control programmes to reduce contaminationof water bodies with S. japonicum but designing control measures for feral animalssuch as rats would be much more difficult to implement than those for domesticanimals such as cattle and dogs.It is important to point out that the intermediate host of S. japonicum isamphibious and therefore simple environmental management of canals is not asolution; rather interruption of the zoonotic cycle must also include animalwaste management in order to have a significant impact on transmission of thisimportant pathogen to humans.2.3.2 Bacterial pathogensE. coli O157:H7 and other enterohemorrhagic E. coli RANK 2 Most strains ofthe bacteria E. coli are thought to be harmless commensals which reside in thegastrointestinal tract of warm-blooded animals. Its widespread occurrence infaeces and the ease with which it can be cultured in the laboratory has led to itsuse as indicator of faecal contamination of water and food. While most membersof the species are non-pathogenic, others belong to “pathogroups” that are