Background
Since the fall of 1999, USGS has been testing wild birds and mammals for West Nile virus infection. USGS has been coordinating a multi-state surveillance network along the Eastern Seaboard and the Gulf Coast to detect and monitor the movement of West Nile Virus in wild birds.

USGS Mapping continues to work with the Centers for Disease Control to produce national maps of West Nile Virus surveillance data, from cooperating states, for the National Atlas of the United States. These products are available to the public through the National Atlas website.

Fall 2000 Update
Wild bird surveillance has proven to be an effective tool for detecting the local presence and spread of virus activity. The possible dissemination of the virus to southern locations offers new and increasing challenges for both public health and USGS wildlife disease specialists. Wildlife involvement in the expanding West Nile virus activity in the United States has become more intense and complex with the increasing number and variety of bird species testing positive in 2000, along with the recent finding of positive bats in New York. To date West Nile virus has been isolated from over 40 species of birds, including at least 35 free-ranging native species. The ongoing southward migration of millions of birds from and through the current 500 mile wide infected region in the northeastern United States increases the risk of dissemination of West Nile virus southward along the Atlantic coastal states.

USGS West Nile Activity
Since the fall of 1999, USGS has invested over $1,000,000 in the West Nile Virus investigation. In addition to testing over 1,400 birds and mammals (including 150 bats) from 25 states and over 3,700 blood samples collected from 10 Atlantic coastal states, USGS has sent field teams to New York and New Jersey on 3 occasions, provided GIS and remote sensing support for field response teams, and enhanced the National Atlas website to provide public access to information on the geographic distribution of the disease.

During July and August of 2000, USGS conducted two extensive field investigations in New York’s Rockland and Westchester counties and New Jersey’s Bergen County to detect the level of West Nile virus activity in wild birds. USGS continues to provide diagnostic support to state and local public health agencies who are utilizing positive dead crows as sentinels for making decisions about human risk and mosquito control efforts.

For more information about West Nile virus and other wildlife diseases, contact Dr. Robert McLean at the USGS National Wildlife Health Center; 608-270-2401.