LAUSR

This issue of Infectious Disease Clinics of North America is titled “Updates in Tropical Medicine.” Today, even more than in the past, terms like “tropical medicine” and “tropical diseases” are nearly impossible to define sensibly. Once upon a time, the terms applied to conditions found predominantly in those parts of the world known as the “tropics” (ie, warm and far away from Europe or North America). Clinical parasitology was a dominant component. Over time, new terms meant to refine, expand, subdivide, or amalgamate these groups of illness came into use. Geographic medicine, travel medicine, and migration medicine are a few of these. Many of the illnesses were more properly diseases of poverty, crowding, and poor access to health resources, and so they remain too often today. In recent years, “tropical medicine” has to some extent been subsumed into the broader notion of “global health,” a term whose current ubiquity owes much to the fact it means nothing specific. Yet, in 2019, “tropical diseases,” or whatever we choose to call them, still carry a huge burden of illness and are expanding their range in many cases. Several illnesses are now seen more frequently in regions where health care practitioners have little familiarity with their presenting features, diagnosis, or management. Climate change and accelerating urbanization have expanded the range of several geographically restricted pathogens or their vectors in the last decade. Human mobility, via ever-increasing international travel and unprecedented mass migrations between distant corners of the globe, has also entailed the spread of imported exotic diseases. Human intrusions into new habitats can uncover new emerging infections, typically zoonotic, or spread disease into new populations. Already several times in the twenty-first century, unexpected mutations in pathogens or vectors have led to altered transmission, virulence, or clinical presentations of known pathogens. The proliferation of immune suppressive therapies and better survival with immune