Rat control measures:
1. Sanitation
2. Trapping: Bait is used. Causes temporary reduction in numbers.
Captured rats must be killed as they become “trap-wise” and avoid traps later
The recommended method of killing rats is by drowning as the rat fleas are killed too. Otherwise the fleas leave the dead rat and may bite humans and other mammals, thereby spreading disease.
3. Rodenticides 
Reference:
K. Park, 2019. Environment and Health, In: Park’s Textbook of Preventive and Social Medicine, 25th ed. Jabalpur, 2019