A disease is something that is contracted from many various ways. For example: The air, water sources, and even food.
Many types of diseases are caused by coming in contact with bacteria, viruses, and even parasites.
Disease is something that can make you sick for a while if you come in contact with a certain pathogen, virus, and much more. In alot of cases disease's can take over the host body, and easily can be treated but that't not always the case. Disease's are something that can be treated with multiple round's of treatment.