Technically, I guess Shelley would be a specialized type of epizoologist (or epizootiologist) - someone who studies patterns of diseases in animals.
Epidemiology comes from the word epidemic, which means visited upon humans. It was given its medical meaning by Hippocrates. But the study of epidemiology has become broader than only epidemics. And the profession is growing, too.
"Clinical epidemiology" was proposed as a discipline by John Paul in 1938. He described it as concerned with a deeper understanding of the patient and the social determinants of health. The first textbooks on clinical epidemiology were published in the 1980s: you can read more about the history here.
Around the same time, the term "evidence-based medicine" came into vogue, a concept that had unfortunately shed the social determinants' focus along the way. Without a notion of "unbiased" embedded in it either, evidence-based medicine is in danger of becoming a label that can be applied to almost anything. But clinical epidemiology rocks on!