Break-bone fever

Aided by global warming and uncontrolled urbanization, dengue fever has increased rapidly in many parts of the world in recent years. What should travelers do when they visit an area that has experienced an epidemic? On a recent visit to Cambodia, outside a children’s hospital a block from my hotel, I saw a large red-and-white sign that warned of a severe epidemic of dengue hemorrhagic fever. Years ago, the disease killed our tour guide’s 5-year-old brother. My tripmates and I managed to escape even the milder form of this mosquito-borne viral infection — we all slept in an air-conditioned hotel and each day applied insect repellent with 30 percent DEET on our exposed skin. But I have since...