TY - JOUR AU - Williams, Roy AU - Malherbe, Johan AU - Weepener, Harold AU - Majiwa, Phelix AU - Swanepoel, Robert T1 - Anomalous High Rainfall and Soil Saturation as Combined Risk Indicator of Rift Valley Fever Outbreaks, South Africa, 2008–2011 T2 - Emerging Infectious Disease journal PY - 2016 VL - 22 IS - 12 SP - 2054 SN - 1080-6059 AB - Rift Valley fever (RVF), a zoonotic vectorborne viral disease, causes loss of life among humans and livestock and an adverse effect on the economy of affected countries. Vaccination is the most effective way to protect livestock; however, during protracted interepidemic periods, farmers discontinue vaccination, which leads to loss of herd immunity and heavy losses of livestock when subsequent outbreaks occur. Retrospective analysis of the 2008–2011 RVF epidemics in South Africa revealed a pattern of continuous and widespread seasonal rainfall causing substantial soil saturation followed by explicit rainfall events that flooded dambos (seasonally flooded depressions), triggering outbreaks of disease. Incorporation of rainfall and soil saturation data into a prediction model for major outbreaks of RVF resulted in the correctly identified risk in nearly 90% of instances at least 1 month before outbreaks occurred; all indications are that irrigation is of major importance in the remaining 10% of outbreaks. KW - Rift Valley fever KW - forecasting KW - soil saturation KW - rainfall KW - vectorborne KW - South Africa KW - outbreaks KW - epizootics KW - epidemics KW - risk indicator KW - zoonoses KW - prediction models KW - viruses KW - livestock KW - vaccination KW - herd immunity KW - mosquito vectors KW - mosquitoes KW - vector-borne infections KW - Vaccine DO - 10.3201/eid2212.151352 UR - https://wwwnc.cdc.gov/eid/article/22/12/15-1352_article ER - End of Reference