Health minister Rajitha Senaratne has instructed regional health directors to conduct health camps in those areas.
The medicine required has been sent to treat the needy, he told a meeting at the Kalutara district secretariat.
He also gave instructions that drinking wells be cleaned as they have got contaminated by overflowing septic pits.
Meanwhile, the Government Information Department cautions the public against crocodile attacks following the overflowing of the Nilwala River.