It largely depends on what you are looking for in terms of disease research. You could earn a Masters in Public Health with a focus on epidemiology in about two years once you are finished with undergraduate studies. It helps to intern somewhere (in graduate school) that focuses on what you are interested in. For the biological side it will range on what you see yourself doing. If you are going to run a lab focused on virology, immunology, parasitology, or something in that vein, you will have to earn a PhD and probably do a few years of post-doc research.
The research will also continue for the rest of your life but it's probably going to be at least ten years of study. Don't let that discourage you though. While you are studying and working in the lab under a Primary Investigator you may have the opportunity to publish articles and you are paid (not very much) to earn a PhD.
Best of luck,