1Schistosomiasis Snails in lakes and rivers in Brazil, northern Africa, and Southeast Asia carry microscopic fluke larvae that cause fever, diarrhea, and possibly deadly seizures from brain lesions.
2Leptospirosis Animal-urine-tainted water, common in Southeast Asia and India, breeds biting parasites that bring on fever, chills, kidney failure, and internal hemorrhaging.
3Leishmaniasis Sand-fly bites in the tropics and subtropics can cause oozing sores, anemia, and a swollen spleen and liver.
4River Blindness On river shores in Central Africa, Yemen, and Central America, bites from female blackflies infected with a worm parasitecause cysts and sometimes blindness.
5African Sleeping Sickness Fever, skin lesions, rash, and possible brain swelling are the woes that tsetse flies bestow in the tropical African savanna.
6Dengue Fever It's a tropical/subtropical mosquito-borne virus featuring headache, chills, fever—and nasty complications like internal hemorrhaging and deadly pneumonia.
7Japanese Encephalitis Get vaccinated against this virus before heading to the Far East or eastern Russia to avoid mosquito-bite-induced paralysis, seizures, and, in advanced cases, coma or death.
8Lymphatic Filariasis Tropical mosquitoes squirt parasitic worms into your blood, causing yourlymph nodes—and, at worst, testicles—to swell to the size of coconuts.
9The Plague This devastating 14th-century bacterial disease, transmitted by fleas, is still imparting open sores and swollen lymph nodes (which can hemorrhage and cause gangrene) anywhere wild rodents thrive.
10Rift Valley Fever Use extreme caution when traveling to African regions—including the Senegal River Basin and the Nile Delta—during outbreaks of this rare flea-, spider-, and mosquito-borne killer.