The Michigan Department of Community Health Bureau of Laboratories conducts testing for the 4 mosquito-borne viruses that can cause illness in humans in Michigan. These include West Nile virus (WNV), St. Louis encephalitis virus (SLE), La Crosse encephalitis virus (LAC), and Eastern Equine encephalitis virus (EEE). In anticipation of the arrival of WNV in Michigan, the MDCH initiated active surveillance in 2001 by alerting selected hospitals and physicians and requesting specimens for arboviral testing on hospitalized patients with signs of meningitis or encephalitis with an unknown cause. No human cases were identified in 2001. In 2002, "Guidelines for Arboviral Serologies" were distributed to physicians, hospitals, and laboratories throughout Michigan to advise these groups as to the testing available through MDCH Bureau of Laboratories. As a result, more than 2900 specimens were tested for WNV and other arboviruses in 2002, and 644 laboratory positive cases of WNV detected. In addition, because of the large number of specimens screened for WNV, 21 cases of other human arboviral infections were detected in Michigan, including 11 cases of LAC, 6 cases of EEE, 3 cases of SLE, and 1 case of Powassan virus, a tick-borne encephaltitis virus discovered for the first time in a Michigan citizen.  This testing continues to be offered by MDCH Bureau of Laboratories.  Testing for West Nile Virus and other arboviruses in human specimens is conducted by the MDCH Bureau of Laboratories from April through October.

CDC Fact Sheet: Testing and Treating West Nile Virus in Humans