West Nile Virus cases in the United States

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West Nile Virus cases in the United States

West Nile Virus (WNV) is a potentially serious illness that can infect humans, birds, mosquitoes, horses and some other mammals. It is a flavivirus commonly found in Africa, West Asia and the Middle East, and is closely related to St. Louis encephalitis virus. Center for Disease Control (CDC) scientists believe the potentially fatal virus has been in the eastern U.S. since the early summer of 1999, and possibly even longer. Experts believe the continued presence and expansion of West Nile virus in the United States indicates that it is now permanently established in the Western Hemisphere, bringing about a seasonal epidemic in North America that flares up in the summer and continues into the fall.

State and local health departments report data on local infections to the Center for Disease Control, allowing the CDC to compile the statistics shown on the maps below.

Maps showing the distribution of West Nile Virus cases

The maps below show the distribution of human, avian, animal or mosquito cases of West Nile virus in the United States. These maps chart the proliferation of the disease as it spread across America from 1999 through 2007.

Lighter shading of states indicates avian, animal or mosquito WNV cases, while darker shading shows the presence of the disease in humans. Shading of a state does not necessarily indicate that WNV was present throughout the entire state since even a single case of West Nile virus infection reported to the Center for Disease Control causes the entire state to be shaded. The number assigned to shaded states specifies the actual number of human cases of WNV reported to the CDC from that state during the year indicated.

West Nile Virus cases in 1999

The above map shows cases of West Nile virus reported by state and local health departments to the CDC during 1999 and covers the period January 1, 1999 through December 31, 1999. During 1999, avian, animal or mosquito WNV infections were reported to the CDC from Connecticut, Maryland, New Jersey, and New York, while human cases were confined to New York.

West Nile Virus cases in 2000

The above map shows cases of West Nile virus reported by state and local health departments to the CDC during 2000 and covers the period January 1, 2000 through December 31, 2000. During 2000, avian, animal or mosquito WNV infections were reported to the CDC from Connecticut, Delaware, District of Columbia, Maryland, Massachusetts, New Hampshire, New Jersey, New York, North Carolina, Pennsylvania, Rhode Island, Vermont, and Virginia, while human cases were reported in Connecticut, New Jersey, and New York.

West Nile Virus cases in 2001

The above map offers information on cases of West Nile virus reported by state and local health departments to the CDC during 2001 and covers the period January 1, 2001 through December 31, 2001. During 2001, avian, animal or mosquito WNV infections were reported to the CDC from Alabama, Arkansas, Connecticut, Delaware, District of Columbia, Florida, Georgia, Indiana, Illinois, Iowa, Kentucky, Louisiana, Maine, Maryland, Massachusetts, Michigan, Mississippi, Missouri, New Hampshire, New Jersey, New York, North Carolina, Ohio, Pennsylvania, Rhode Island, Tennessee, Virginia, and Wisconsin, while human cases were reported in Alabama, Connecticut, Florida, Georgia, Louisiana, Maryland, Massachusetts, New Jersey, New York, and Pennsylvania.

West Nile Virus cases in 2002

The above map highlights the presence of West Nile virus as reported by state and local health departments to the CDC during 2002 and covers the period January 1, 2002 through April 15, 2003. During this period, avian, animal or mosquito WNV infections were reported to the CDC from Alabama, Arkansas, Colorado, Connecticut, Delaware, District of Columbia, Florida, Georgia, Idaho, Illinois, Indiana, Iowa, Kansas, Kentucky, Louisiana, Maine, Maryland, Massachusetts, Michigan, Minnesota, Mississippi, Missouri, Montana, Nebraska, New Hampshire, New Jersey, New Mexico, New York, North Carolina, North Dakota, Ohio, Oklahoma, Pennsylvania, Rhode Island, South Carolina, South Dakota, Tennessee, Texas, Vermont, Virginia, Washington, West Virginia, Wisconsin and Wyoming, while human cases were reported in Alabama, Arkansas, California, Colorado, Connecticut, Delaware, District of Columbia, Florida, Georgia, Illinois, Indiana, Iowa, Kansas, Kentucky, Louisiana, Maryland, Massachusetts, Michigan, Minnesota, Mississippi, Missouri, Montana, Nebraska, New Jersey, New York, North Carolina, North Dakota, Ohio, Oklahoma, Pennsylvania, Rhode Island, South Carolina, South Dakota, Tennessee, Texas, Vermont, Virginia, West Virginia, Wisconsin and Wyoming.

West Nile Virus cases in 2003

The above map offers numerical totals of human cases of West Nile virus reported by state and local health departments to the CDC during 2003 and covers the period January 1, 2003 through December 31, 2003. During 2003, avian, animal or mosquito WNV infections were reported to the CDC from Alabama, Arizona, Arkansas, California, Colorado, Connecticut, Delaware, District of Columbia, Florida, Georgia, Illinois, Indiana, Iowa, Kansas, Kentucky, Louisiana, Maine, Maryland, Massachusetts, Michigan, Minnesota, Mississippi, Missouri, Montana, Nebraska, New Hampshire, New Jersey, New Mexico, New York, North Carolina, North Dakota, Ohio, Oklahoma, Pennsylvania, Rhode Island, South Carolina, South Dakota, Tennessee, Texas, Utah, Vermont, Virginia, West Virginia, Wisconsin and Wyoming, while human cases were reported in Alabama, Arizona, Arkansas, California, Colorado, Connecticut, Delaware, District of Columbia, Florida, Georgia, Idaho, Illinois, Indiana, Iowa, Kansas, Kentucky, Louisiana, Maryland, Massachusetts, Michigan, Minnesota, Mississippi, Missouri, Montana, Nebraska, Nevada, New Hampshire, New Jersey, New Mexico, New York, North Carolina, North Dakota, Ohio, Oklahoma, Pennsylvania, Rhode Island, South Carolina, South Dakota, Tennessee, Texas, Utah, Vermont, Virginia, West Virginia, Wisconsin and Wyoming.

West Nile Virus cases in 2004

The above map shows the number of human cases of West Nile virus reported by state and local health departments to the CDC during 2004 and covers the period January 1, 2004 through December 31, 2004. During 2004, avian, animal or mosquito WNV infections were reported to the CDC from Alabama, Arizona, Arkansas, California, Colorado, Connecticut, Delaware, District of Columbia, Florida, Georgia, Idaho, Illinois, Indiana, Iowa, Kansas, Kentucky, Louisiana, Maine, Maryland, Massachusetts, Michigan, Minnesota, Mississippi, Missouri, Montana, Nebraska, Nevada, New Hampshire, New Jersey, New Mexico, New York, North Carolina, North Dakota, Ohio, Oklahoma, Oregon, Pennsylvania, Rhode Island, South Carolina, South Dakota, Tennessee, Texas, Utah, Vermont, Virginia, West Virginia, Wisconsin, Wyoming, and Puerto Rico, while human cases were reported in Alabama, Arizona, Arkansas, California, Colorado, Connecticut, District of Columbia, Florida, Georgia, Idaho, Illinois, Indiana, Iowa, Kansas, Kentucky, Louisiana, Maryland, Michigan, Minnesota, Mississippi, Missouri, Montana, Nebraska, Nevada, New Jersey, New Mexico, New York, North Carolina, North Dakota, Ohio, Oklahoma, Oregon, Pennsylvania, South Carolina, South Dakota, Tennessee, Texas, Utah, Virginia, Wisconsin, and Wyoming.

West Nile Virus cases in 2005

The above map indicates how many human cases of West Nile virus were reported by state and local health departments to the CDC during 2005 and covers the period January 1, 2005 through December 31, 2005. During 2005, avian, animal or mosquito WNV infections were reported to the CDC from Alabama, Arizona, Arkansas, California, Colorado, Connecticut, Delaware, District of Columbia, Florida, Georgia, Idaho, Illinois, Indiana, Iowa, Kansas, Kentucky, Louisiana, Maine, Maryland, Massachusetts, Michigan, Minnesota, Mississippi, Missouri, Montana, Nebraska, Nevada, New Hampshire, New Jersey, New Mexico, New York, North Carolina, North Dakota, Ohio, Oklahoma, Oregon, Pennsylvania, Rhode Island, South Carolina, South Dakota, Tennessee, Texas, Utah, Vermont, Virginia, Washington, West Virginia, Wisconsin, and Wyoming, while human cases were reported in Alabama, Arizona, Arkansas, California, Colorado, Connecticut, Delaware, District of Columbia, Florida, Georgia, Idaho, Illinois, Indiana, Iowa, Kansas, Kentucky, Louisiana, Maryland, Massachusetts, Michigan, Minnesota, Mississippi, Missouri, Montana, Nebraska, Nevada, New Jersey, New Mexico, New York, North Carolina, North Dakota, Ohio, Oklahoma, Oregon, Pennsylvania, Rhode Island, South Carolina, South Dakota, Tennessee, Texas, Utah, Virginia, Wisconsin, and Wyoming.

West Nile Virus cases in 2006

The above map shows cases of West Nile virus reported by state and local health departments to the CDC during 2006 and covers the period January 1, 2006 through December 31, 2006. During 2006, avian, animal or mosquito WNV infections were reported to the CDC from Alabama, Arizona, Arkansas, California, Colorado, Connecticut, Delaware, District of Columbia, Florida, Georgia, Idaho, Illinois, Indiana, Iowa, Kansas, Kentucky, Louisiana, Maine, Maryland, Massachusetts, Michigan, Minnesota, Mississippi, Missouri, Montana, Nebraska, Nevada, New Hampshire, New Jersey, New Mexico, New York, North Carolina, North Dakota, Ohio, Oklahoma, Oregon, Pennsylvania, Rhode Island, South Carolina, South Dakota, Tennessee, Texas, Utah, Vermont, Virginia, Washington, West Virginia, Wisconsin, and Wyoming, while human cases were reported in Alabama, Arizona, Arkansas, California, Colorado, Connecticut, District of Columbia, Florida, Georgia, Idaho, Illinois, Indiana, Iowa, Kansas, Kentucky, Louisiana, Maryland, Massachusetts, Michigan, Minnesota, Mississippi, Missouri, Montana, Nebraska, Nevada, New Jersey, New Mexico, New York, North Carolina, North Dakota, Ohio, Oklahoma, Oregon, Pennsylvania, South Carolina, South Dakota, Tennessee, Texas, Utah, Virginia, Washington, West Virginia, Wisconsin, and Wyoming.

West Nile Virus cases in 2007

The above map shows cases of West Nile virus reported by state and local health departments to the CDC during 2007, as of April 1, 2008. During 2007, avian, animal or mosquito WNV infections were reported to the CDC from Alabama, Arizona, Arkansas, California, Colorado, Connecticut, Delaware, District of Columbia, Florida, Georgia, Idaho, Illinois, Indiana, Iowa, Kansas, Kentucky, Louisiana, Maryland, Massachusetts, Michigan, Minnesota, Mississippi, Missouri, Montana, Nebraska, Nevada, New Hampshire, New Jersey, New Mexico, New York, North Carolina, North Dakota, Ohio, Oklahoma, Oregon, Pennsylvania, Puerto Rico, Rhode Island, South Carolina, South Dakota, Tennessee, Texas, Utah, Vermont, Virginia, Washington, West Virginia, Wisconsin, and Wyoming, while human cases were reported in Alabama, Arizona, Arkansas, California, Colorado, Connecticut, Delaware, Florida, Georgia, Idaho, Illinois, Indiana, Iowa, Kansas, Kentucky, Louisiana, Maryland, Massachusetts, Michigan, Minnesota, Mississippi, Missouri, Montana, Nebraska, Nevada, New Jersey, New Mexico, New York, North Carolina, North Dakota, Ohio, Oklahoma, Oregon, Pennsylvania, Rhode Island, South Carolina, South Dakota, Tennessee, Texas, Utah, Virginia, Wisconsin, and Wyoming.

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