Final answer:
Louis Pasteur made great advances in the area of medicine and health by pioneering the field of bacteriology and proving that disease was caused by microscopic organisms.
Step-by-step explanation:
The scientist who made great advances in the area of medicine and health was Louis Pasteur. Pasteur pioneered the field of bacteriology and proved that disease was caused by microscopic organisms. He developed the technique of pasteurization to make food safe and created effective vaccines against diseases like anthrax. Pasteur's discoveries revolutionized the understanding of health and led to a significant drop in deaths due to infectious diseases.