(d) Plague disease is caused by bacteria. The disease is caused by bacterial strain called Yersinia pestis. This disease is sometimes referred to as black plague. AIDS is caused by virus called HIV (Human Immunodeficiency Virus). It infects the cell of the immune system.Baldness is caused by the fungal infection of ringworm. Malaria is caused by protozoan parasite Plasmodium. It is transmitted by the bite of a female anopheles mosquito.