During the past 15 years, 2002-2016, West Nile virus (WNV) has emerged in South Dakota resulting in 509 neuroinvasive disease (NID) cases, 745 hospitalizations and 38 deaths. Culex tarsalis is the state's primary mosquito vector. South Dakota's average annual incidence of WNV-NID and death rate are the highest of any state in the U.S. WNV cases have been reported from all counties in the state. All age groups have been infected with cases peaking in the 40-44 year age group, but deaths peaking in cases 70 years and older. Although South Dakota's WNV season lasts six months, May-October, the first week of August has been the peak week of WNV disease onsets. West Nile is now enzootic in South Dakota. Every citizen, local mosquito control programs, medical and public health infrastructures must continue to prevent and respond to annual WNV outbreaks, and prepare for the next arboviral disease to emerge.
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