How long after returning home from Sri Lanka should I monitor for dengue symptoms?

You should keep a strict eye on your health for up to fourteen days after leaving Sri Lanka, because the longest incubation window for the dengue virus is two weeks.

If a sudden fever, a severe headache, or an unusual rash appears during those 14 days, then get medical care right away. Make sure you explicitly tell your home-country physician that you have just returned from a dengue-endemic area. Since dengue is not very common in many Western countries, providing your travel background up front helps clinicians do the right tropical disease testing without delay, even when it might not be the first thought.