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Veterinary Medicine International
Volume 2014 (2014), Article ID 379010, 9 pages
Research Article

Detection of Rift Valley Fever Virus Interepidemic Activity in Some Hotspot Areas of Kenya by Sentinel Animal Surveillance, 2009–2012

1Ministry of Agriculture Livestock and Fisheries, P.O. Box 00625, Nairobi, Kenya
2International Livestock Research Institute, P.O. Box 30709–00100, Old Naivasha Road, Nairobi, Kenya
3Kenya Agricultural Research Institute, Biotechnology Centre, P.O. Box 57811-00200, Waiyaki Way, Nairobi, Kenya
4International Centre of Insect Physiology and Ecology, Human Health Division, P.O. Box 30772-00100, Nairobi, Kenya
5Kenya Medical Research Institute, Centre for Virus Research, P.O. Box 54628-00200, Nairobi, Kenya

Received 29 April 2014; Revised 20 July 2014; Accepted 21 July 2014; Published 13 August 2014

Academic Editor: Timm C. Harder

Copyright © 2014 Jacqueline Kasiiti Lichoti et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


Rift Valley fever virus causes an important zoonotic disease of humans and small ruminants in Eastern Africa and is spread primarily by a mosquito vector. In this region, it occurs as epizootics that typically occur at 5–15-year intervals associated with unusual rainfall events. It has hitherto been known that the virus is maintained between outbreaks in dormant eggs of the mosquito vector and this has formed the basis of understanding of the epidemiology and control strategies of the disease. We show here that seroconversion and sporadic acute disease do occur during the interepidemic periods (IEPs) in the absence of reported cases in livestock or humans. The finding indicates that previously undetected low-level virus transmission during the IEPs does occur and that epizootics may also be due to periodic expansion of mosquito vectors in the presence of both circulating virus and naïve animals.