West Nile Virus Spreading West in the U.S.

Adapted and updated from a CDC telebriefing held on July 25, 2002, featuring speaker Dr. Daniel O'Leary.

West Nile Virus Prevention Tips: Spray on DEET-containing mosquito repellent when you go outdoors. Don't let puddles collect in flower pots, wading pools or other spots where mosquitoes can breed. Avoid fresh water lakes, ponds, streams after dark. Check children and pets for mosquitoes before they go inside.

During 2002, West Nile Virus activity was reported to the Centers for Disease Control and Prevention from 25 states, New York City, and the District of Columbia. There have been a total of 12 human cases of brain infection with West Nile. All of those cases were reported from Louisiana and Mississippi: eleven from Louisiana and one from Mississippi. Among these cases, eight were men. The range of ages was 34 to 88 years, and their dates of onset of illness ranged from June 10 to July 11. None of these 12 cases are fatalities.

Additionally, there have been seven states--Minnesota, Nebraska, North Dakota, Oklahoma, South Dakota, Texas, and West Virginia--that have reported their first-ever West Nile Virus activity, but so far only in birds, horses, and mosquitoes, with no human cases. The spread to these states demonstrates that West Nile Virus is continuing to move Westward in the United States.

Dead birds, particularly blue jays and crows, remain the most important indicators of West Nile Virus activity in a given region, and their collection and testing by state and local health departments should be a mainstay in these jurisdictions' surveillance programs. The capture and testing of mosquitoes is very important as a mainstay of state-level surveillance and, additionally, surveillance for West Nile Virus in horses and other equines has proven a valuable tool to indicate an early warning of West Nile activity in select areas.

At a minimum, we're asking states to conduct human surveillance to include West Nile Virus testing for patients with encephalitis or of a cause to which other diagnoses cannot be ascribed.

The message here is that human and animal illness prevention depends on sustained and long-term control of the mosquitoes that spread West Nile Virus, especially in populated areas. Detection should happen as early as possible and should be followed by intensified mosquito control in areas where the virus is found, especially in populated areas. People should also take personal responsibility for protecting themselves against mosquito bites, including the use of protective clothing and repellents.

The final line is that West Nile Virus is endemic - it is established - in the United States. Personal protection against mosquitoes, effective mosquito control at the local level, and early detection are all mainstays of prevention.

For more information on West Nile Virus visit these pages on HOOAH 4 HEALTH:
West Nile Encephalitis
West Nile Encephalitis FAQ

And for preparation of Soldier uniforms for protection against insects:
DOD Insect Repellent System

Click here for the full transcript of the July 25, 2002 CDC telebriefing.
Since this briefing additional reports of WNV activity have been made. The article on this page has the latest information as of July 31, 2002.

As of 3:00 PM (MDT), August 16, 2002 there have been an additional 251 human cases reported with 11 fatalities. Click here for a CDC Press Release of these recent totals.