About West Nile Virus

Mosquito transmission

West Nile virus (WNV) is carried by mosquitoes and transmitted via a bite from an infected mosquito. It can infect humans, birds, mosquitoes, horses and some other mammals.

Potentially serious or fatal disease

In humans, it can cause potentially serious or fatal diseases including West Nile Fever and West Nile Encephalitis (inflammation of the brain). People typically develop symptoms between 3 and 14 days after they are bitten by the infected mosquito.

Rapid U.S. spread

WNV is a flavivirus commonly found in Africa, West Asia and the Middle East. It has also been found in Europe and more recently, in the United States and Canada.

WNV was first recognized in the United States in 1999 as the cause of severe illness and fatalities in humans in metropolitan New York City. The virus has since spread rapidly throughout the country.

Early detection designed to improve blood safety

The Procleix® West Nile Virus Assay is currently supported under a clinical protocol for investigational use only. It is specifically designed to meet published FDA performance guidelines1 for direct detection of the West Nile virus in donated blood, plasma, organs and tissue.

No specific treatment

There is no specific treatment for West Nile virus infection.

Avoiding mosquitoes best prevention

The simplest way to avoid contracting WNV virus is to avoid contact with mosquitoes and use mosquito repellents to avoid mosquito bites. As mosquitoes lay their eggs in standing water, draining standing water around the house, such as in flower pots, rain gutters and swimming pool covers, can help to reduce the mosquito population and slow the spread of WNV.

Final 2005 West Nile Virus Activity in the United States

This map reflects surveillance findings occurring between January 1, 2005 through December 31, 2005 as reported to CDC's ArboNET system for public distribution by state and local health departments.

Final 2005 West Nile Virus Activity in the United States


Grifols and Novartis have announced an agreement for Grifols to acquire the transfusion diagnostics unit of Novartis.

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