So, let's talk about Rift Valley Fever!
The Great Rift Valley is a massive crack in the earth's crust (a.k.a. - "rift") that basically splits Kenya in two, from north to south. Rumor has it that the Great Rift Valley was discovered by a woman, but no one believed her.
In 1910, Kenya's Rift Valley region started seeing cases of pregnant livestock spontaneously aborting their offspring. This disease was the start of a long history with Rift Valley Fever Virus (RVFV), a Phlebovirus of the Bunyaviridae family. RVFV was eventually identified as a zoonotic agent, infecting people with contact with infected livestock. Mosquitoes were eventually identified as the vector for RVFV when incidence spiked after rainy seasons, as flooding increases potential breeding areas for mosquitoes.
|Cows in Kenya - photo from Wildlife Direct|
RVFV is an enveloped, single-stranded RNA virus. The RVFV genome is divided into 3 segments of differing sizes (small, medium, and large), all of which are circularized. Host cells targeted during infection include macrophages, hepatocytes, and endothelial cells.
|A computer modeled 3D structure of RVFV - image from Dr. Juha Huiskonen|
Given the severe affects on livestock reproductive viability, RVFV outbreaks can have devastating affects on the economy. Not only can you lose a large amount of your livestock population through death of the infected animal, and future generations by abortion, but once infected animals are identified, you are banned from trading livestock for an extended period of time. This process has been very effective in containing RVFV to the continent, but not all infected animals present symptoms prior to trade or breeding. With a large enough outbreak, severe economic collapse could follow.
|An unfortunate casualty - Image from The Travel Doctor|
The United States Department of Agriculture (USDA) has listed RVFV as a major threat to the U.S. because of the large economic dependency we have on livestock. Even though the virus has only started to leave Africa, the U.S. does have the vectors to support spread to North America.