MALARIA
SPREAD BY: Mosquitoes
KILL RATE: 0.2%
DEATH TOLL: 1 million+ per year
As climate change makes parts of the glabal warmer and wetter, populations of the disease's host, the Anopheles mosquito, are likely to swell. Malaria kills by destroying blood cells and causing kidney failure. Resistance has become such a problem that the WHO now supports the use of the controversial insecticide DDT, once widely banned, to control Anopheles populations in Africa.
The life cycle of Malaria
SMALLPOX
SPREAD BY: Bioterrorism or clinical accident.
KILL RATE: 30%
DEATH TOLL: 500 million; 2 million per year in 1960s
Well, this isn't out in the wild. Anymore. Worldwide vaccination programs eradicated smallpox by1980, but 2 government-approved labs in the U.S. and Russia keeps stores of it. A 2006 investigate report by The Guardian determined that, though very unlikely, it could be made from scratch, or someone could just steal it. Since smallpox is very contagious, the CDC would consider even one confirmed case a "public-health emergency". Vaccines exist, but they can cause serious side effects. There is no cure.
Face lesions on boy with Smallpox
WEST NILE VIRUS
SPREAD BY: Mosquitoes
KILL RATE: 4%
DEATH TOLL: 1 086 (U.S. only)
No one knows how West Nile Virus first got to the U.S. in 1999, but in has since exploded across the country. Less than 1% of people end up with severe complications such as meningitis, fatal encephalitis and polio-like paralysis. There is no cure for the infection, though, so stock up on bug spray.
Map of West Nile Virus Risk
EBOLA
SPREAD BY: Body fluids
KILL RATE: 50%-90%
DEATH TOLL: 1 507
Ebola is so deadly that outbreaks have, to this point, quickly burned themselves out; direct contact with infected individuals is required for transmission, and victims generally expire before they can travel far. The virus strips in the lining in victim's blood vessels, causing massive internal bleeding. Woe betide humanity if Ebola mutates and becomes transmissible by air.
An Ebola victim
DENGUE FEVER
SPREAD BY: Mosquitoes
KILL RATE: 0.05%
DEATH TOLL: 10 000+ per year
The mosquitoes that carry dengue, Aedes aegypti and Aedes albopictus, thrive in warm, wet climates. Like malaria, dengue fever (a.k.a. "breakbone fever") is a debilitating disease. Of those who develop more aggressive dengue hemorrhagic fever, 5% die, typically from internal bleeding.