A potentially important influence on the transmission of FZTs
in freshwater fish is the presence of reservoir hosts, such as cats,
dogs, and pigs, which may contaminate the environment with FZT
eggs (Chai et al., 2005a,b). In this area, cats, dogs, and pigs are not
restrained, and can defecate anywhere in the village or floodplain
area during the dry season. The role of these hosts needs much
closer examination, especially since recent strategies for control
of FZTs place strong emphasis primarily on mass drug treatment
of the human population (WHO, 2004). Not only humans but also
domestic animalsmay contribute to contaminatewater bodies with
faecal eggs, leading to snail and fish infections. Community based
survey on human, domestic animals and fish should be performed
in the near future.