Why is the immune system essential for our health?

We should not allow mosquitoes to breed in our surroundings because they :

Bacterial diseases are:

State whether the following statement is true or false:
The diseases which last for only short periods of time are called chronic diseases.

Give the cause and remedy for:
$(a)$ Hepatitis
$(b)$ $AIDS$
$(c)$ Malaria

Mahima is suffering from cholera. It is likely that the children sitting around her will be exposed to the infection:
$(a)$ Do all the students get infected and suffer from disease?
$(b)$ List two major symptoms of cholera.
$(c)$ What are the different ways of spread of this disease?