Related Experiment Video
Updated: Jun 4, 2026

Using Reverse Genetics to Manipulate the NSs Gene of the Rift Valley Fever Virus MP-12 Strain to Improve Vaccine Safety and Efficacy
Published on: November 1, 2011
Sequential Rift Valley fever outbreaks in eastern Africa caused by multiple lineages of the virus
Leonard Nderitu1, John S Lee, Jared Omolo
1Global Disease Detection Division, United States Centers for Disease Control and Prevention-Kenya, Nairobi, Kenya.
Background:
During the Rift Valley fever (RVF) epidemic of 2006-2007 in eastern Africa, spatial mapping of the outbreaks across Kenya, Somalia, and Tanzania was performed and the RVF viruses were isolated and genetically characterized.
Methods:
Following confirmation of the RVF epidemic in Kenya on 19 December 2006 and in Tanzania on 2 February 2007, teams were sent to the field for case finding. Human, livestock, and mosquito specimens were collected and viruses isolated. The World Health Organization response team in Kenya worked with the WHO's polio surveillance team inside Somalia to collect information and specimens from Somalia.
Results:
Seven geographical foci that reported hundreds of livestock and >25 cases in humans between December 2006 and June 2007 were identified. The onset of RVF cases in each epidemic focus was preceded by heavy rainfall and flooding for at least 10 days. Full-length genome analysis of 16 RVF virus isolates recovered from humans, livestock, and mosquitoes in 5 of the 7 outbreak foci revealed 3 distinct lineages of the viruses within and across outbreak foci.
Conclusion:
The findings indicate that the sequential RVF epidemics in the region were caused by multiple lineages of the RVF virus, sometimes independently activated or introduced in distinct outbreak foci.
Related Concept Videos
Rocky Mountain Spotted Fever
Yellow Fever
Rabies
Arboviral Encephalitis
Viral Recombination
Respiratory Syncytial Virus Disease

