doctor with a patientExperts believe West Nile virus (WNV) is now an established seasonal epidemic in North America. In Missouri, human WNV cases generally occur in late summer and early fall. Rapid identification and reporting of active human West Nile virus infections provides state and local public health agencies with timely information on the location and prevalence of the virus.


Diagnostic Testing

Free WNV diagnostic testing for patients with encephalitis, meningitis, uncomplicated fever, or other illness with central nervous system involvement can be obtained through the Missouri State Public Health Laboratory (SPHL) in Jefferson City (phone 573/751-3334 or 751-0633). Specimen shipment instructions and the Virus Serology Test Request form can be downloaded from the SPHL website.

Reporting Human Cases of WNV

Domestic Arboviral Diseases, both neuroinvasive and non-neuroinvasive, are reportable by statute in Missouri under public health rule 19 CSR 20-20.020, Reporting Communicable, Environmental, and Occupational Diseases. Reporting should be etiology-specific: St. Louis encephalitis virus disease, West Nile virus disease, Powassan virus disease, Eastern equine encephalitis virus disease, Western equine virus disease, California serogroup virus disease (includes infections with the following viruses: La Crosse, Jamestown Canyon, snowshoe hare, trivittatus, Keystone, and California encephalitis viruses). Missouri Department of Health and Senior Services Disease Case Report – CD-1 (and instructions).

The Missouri Department of Health and Senior Services (DHSS) has built a WNV surveillance system that includes mosquito trapping, testing dead birds for infection, and assessing human case activity. Tracking the virus’ activity in birds and mosquitoes gives communities a "heads-up" that people are at greater risk of becoming ill with these infections. The WNV Data & Statistical Reports page is updated weekly from April through October.

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