English physician who was among the first to examine the role of infectious agents in the spread of disease. To contain the spread of disease, Haygarth practiced separating infectious patients from those with other ailments—at the time a novel idea. His insistence on cleanliness standards, well-ventilated rooms, and other innovations were viewed with skepticism, but his success rate led to their widespread adoption by other physicians. Haygarth was also active in debunking many questionable medical claims.