Dear student,
a)The disease the person is suffering from is fungal disease which is generally called as ringworm.
In this type of disease the person suffers from dry, scaly lesions on his skin, nails and scalp which is accompanied by intense itching.
b)He would have contracted or prevented from the disease by taking certain precautions:
1)Keeping the floor and the soft furnishings cleaned and vacuumed.
2)Pets at home should be taken for regular checkups.
3)Antifungal preparations can be prescribed by the doctors which can be applied on the infected areas or fungal affected areas.
4)Nails should be kept clean and dry.
Regards