Question

Diseases spread on a large scale during periods of heavy rainfall and floods.

give reason?​

Answer 1

Diseases spread on a large scale during periods of heavy rainfall and floods because it provides the optimum conditions for the growth of vectors which transmit diseases. After heavy rainfall and floods, water gets accumulated at places and acts as breeding grounds for mosquitoes and other vectors. These vectors lead to the transmission of the microorganisms to their host and result in the development of the disease.  

For example, malaria is caused by a virus that is transmitted by a mosquito.

Answer 2

Answer:

As many water borne diseases spread at a faster rate when we are in contact with infected water.