The number of West Nile virus cases in the United States has reached the 700 mark for the year to date, with approximately 1/3 of cases being reported from two states–California (123) and Texas (105).

West Nile virus
Culex quinquefasciatus

Officially, as of Tuesday, a total of 46 states and the District of Columbia have reported West Nile virus infections in people, birds, or mosquitoes in 2015.

Overall, 708 cases of West Nile virus (WNV) disease in people have been reported to CDC. Of these, 422 (60%) were classified as neuroinvasive disease (such as meningitis or encephalitis) and 286 (40%) were classified as non-neuroinvasive disease.

29 deaths have been attributed to infection with WNV (Texas has recorded 6, the most in the nation).

In 2014, 2,205 human WNV cases were reported, including 97 fatalities.

WNV is most commonly transmitted to humans by mosquitoes. You can reduce your risk of being infected with WNV by using insect repellent and wearing protective clothing to prevent mosquito bites. There are no medications to treat or vaccines to prevent WNV infection.

Fortunately, most people infected with WNV will have no symptoms. About 1 in 5 people who are infected will develop a fever with other symptoms. Less than 1% of infected people develop a serious, sometimes fatal, neurologic illness.

Robert Herriman is a microbiologist and the Editor-in-Chief of Outbreak News Today and the Executive Editor of The Global Dispatch

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