The World Health Organization says Rift Valley fever was first discovered in Kenya in nineteen thirty-one.

VOA: special.2010.07.12

Health officials said last week that there were no cases of Rift Valley fever in tourists.

VOA: special.2010.07.12

Current vaccines to protect against Rift Valley fever are limited to use in animals.

VOA: special.2010.07.12

These were the first reported cases of Rift Valley fever outside of Africa.

VOA: special.2010.07.12

Rift Valley fever mainly affects farm animals.

VOA: special.2010.07.12

Also a nearby volcano erupted four years ago,ripping open a crack in the Great Rift Valley.

VOA: standard.2009.12.14

"The Rift Valley gives you a scenario of human evolution,"

VOA: standard.2009.12.14

Yes,you can see horns." These 500 to 1000-year-old cave paintings are young compared to the skeleton of Ardi, an upright hominid more than four million years old discovered in Ethiopia's Great Rift Valley .

VOA: standard.2009.12.14