But patients with more severe forms can go blind. Some develop encephalitis, a brain disease that can lead to headaches, coma or seizures. And some patients bleed to death.
The World Health Organization says Rift Valley fever was first discovered in Kenya in nineteen thirty-one. In the year two thousand, it was identified in Saudi Arabia and Yemen. These were the first reported cases of Rift Valley fever outside of Africa.
Current vaccines to protect against Rift Valley fever are limited to use in animals. But researchers are working to develop the first human vaccine.
In a new study, scientists in the United States tested vaccines made with two kinds of inactivated virus. They said tests in mice showed that their new vaccines are safer than live-virus vaccines and appear to work just as well. Using live virus in vaccines can increase the risks.
The researchers are at the University of Pittsburgh and the University of North Carolina. Their study appeared in the journal PLoS Neglected Tropical Diseases, published by the Public Library of Science,.
And that's the VOA Special English Development Report, written by June Simms. You can read and listen to all of our reports at voaspecialenglish.com. You can also find us on Facebook, Twitter, YouTube and iTunes at VOA Learning English. I'm Steve Ember.
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2013-11-25
2013-11-25
2013-11-25
2013-11-25
2013-11-25
2013-11-25