From UC Davis:
In what researchers say is the first public health study of the aerial mosquito spraying method to prevent West Nile virus, a UC Davis study analyzed emergency department records from Sacramento area hospitals during and immediately after aerial sprayings in the summer of 2005.
The Sacramento-Yolo Mosquito and Vector Control District provided the aerial spraying data.
The data also comes at the same time, the mosquito district is considering whether to spray the West Sacramento area in an effort to prevent the spread of West Nile Virus.
Of particular concern for the district is a 25,000-acre patch of North Sacramento County, north of the American River, where many dead birds have tested positive for the West Nile virus and where an inventory of multiple mosquito samples has also tested positive.
To date, 18 dead birds and 58 mosquito samples have tested positive for West Nile virus in the county. One human case has been reported by the California Department of Public Health.
The West Nile activity, while intensifying in Sacramento County, is widespread. In Yolo County six dead birds and 19 mosquito samples have also tested positive for West Nile virus. Most of the birds that tested positive are of the American crow species. No humans have tested positive for the virus in Yolo County in 2013.
No formal decision has been made on the spraying, which would be used to reduce adult mosquito population.