Dengue is widespread across most of the tropics, with cases often occurring among backpackers on idyllic Southeast Asian islands, but if that's not bad enough daytime biting mosquitoes can also spread tiny worms that cause lymphatic filariasis.
Also known as "elephantiasis," the worms block the lymph nodes of the body's drainage system" causing testicles to swell to the size of beach balls and legs to resemble tree trunks.
In areas of India up to one third of the population may be infected, and the disease is essentially incurable.
So, cover up in the day time as well as the evening, unless you know that it's safe to bare your flesh.
1. Candiru fish
Candiru fish attacks are not a regular occurrence, but the consequences are so dire that it definitely merits its place as the No. 1 craziest threat when traveling.
The way to avoid this blood-sucking fish's unwanted attentions -- don't pee in the Amazon.
Though there's much debate about this fish and alleged tales of its attraction to urine, no man wants one stuck in their urethra, as happened to at least one poor chap in recent years.
Once inside, it will feed on flesh before surgery is required to get it out.