A week in a Phuket resort, a month backpacking through the north, and a stint working upcountry are three different risk profiles under the same country name. For most visitors the practical concerns are food and water rather than anything exotic — which is why hepatitis A and typhoid come up in nearly every consultation, alongside a check that your routine boosters are still in date. Beyond that it depends on the detail: how rural you're going, how long for, what time of year, and whether you'll be around animals. Malaria tablets are rarely needed for the usual tourist route, but mosquitoes still matter, because dengue is common in the cities and on the islands and the mosquitoes that carry it bite during the day.