The study was carried out at and ar

The study was carried out at and around Lake 500 on the border
of Kandal and Takeo provinces, southern Cambodia. The lake
is located on the right side of the Basac River, about 42km from
Phnom Penh City (Fig. 1), and 60km from An Giang Province, South
Vietnam. A total of 45,324 people live in 4 communes with 48 villages
in this area; most of them are farmers and fishermen. Some
products are sold in northeastern Takeo Province and Phnom Penh.
This part of Cambodia is a flood plain, which floods with rainwater
in August–November every year. After the flood has subsided, the
land is used as the paddy. Feeder roads to the lake are a few meters
above ground level, and houses are built along both sides of the
road at road level above the ground. Toilet numbers and usage are
low; people defecate in the bushes or directly into the water