The deadly Rift Valley fever virus is on the move. First detected during the 1930s in southern Africa, the mosquito-borne pathogen had crossed the Sahara into Egypt by 1977 and by 1999 had traversed the Red Sea into Yemen and Saudi Arabia. Now it seems poised to enter the United States—and the results could be devastating.
“To say that Rift Valley fever makes West Nile look like a hiccup is an understatement,” says Mike Turell, a specialist at the U.S. Army Medical Research Institute in Fort Detrick, Maryland. Like West Nile, Rift Valley fever spreads rapidly in the warm weather mosquitoes favor. But Rift Valley fever is much more devastating. Most people who get West Nile don’t even know it, but 90 percent of those infected with the Rift Valley fever virus become demonstrably ill. Symptoms range from weakness and feverish illness to blindness and Ebola-like hemorrhaging. Victims are 10 times more likely to die from it than West Nile.
If Rift Valley fever comes to the United States, it will most likely get here the way most scientists think West Nile did—via a mosquito on an airplane. “While the chance of any particular mosquito-borne virus hitching a ride on an airplane and surviving in the U.S. is like winning the lottery, somebody always wins the lottery,” Turell says. “So it’s more a question of when.”
