Virus is a self instuct program which hiddenly read user data and hack that data.When the phone affect by virus you can see some sugnificant in your phone are bellow which is help you to identify virus-
1st-battery loss rapidly or over the limit.2nd-hanging problem show in your phone.
3rd-over the limit data use.
4rth-suddenly app stoped.
5th-autometically phone swith off.
6th-autometically came back to home screen.
7th-phone speed decrease.