West Nile virus cases have been increasing in Northern California. The West Nile virus is the most common and serious vector-borne disease in the state. There were 29 new West Nile Virus cases in humans last week, bringing the total for the year to 55 cases. Those cases have been reported in Glenn, Lake, Butte, Yolo, El Dorado, Sacramento, San Joaquin, Santa Clara, Stanislaus, Merced, Madera, Kings, Tulare, Kern, Los Angeles, San Bernardino and Riverside counties. On Wednesday, another human case in Roseville became the first this summer in Placer County. Five people with the virus have died, including one person in Sacramento County and another person in Yolo County.