It’s that time of the year and the mosquitoes are biting. With that reality, at least since 1999 in the United States, West Nile virus (WNV) has become an annual issue.


So far in 2014, the Centers for Disease Control and Prevention (CDC) has had 18 human cases reported to CDC ArboNET from Arizona, California, Mississippi, Missouri, South Dakota, Tennessee, and Texas. In addition, at least two other state have reported human WNV cases since the CDC update–Oklahoma and Louisiana. Iowa also reported a human case at the beginning of the month; however, it has yet to be reported by the CDC.

Approximately 20 states have reported WNV activity in mosquitoes, birds, sentinel animals, or veterinary animals–Alabama, Colorado, Florida, Idaho, Illinois, Indiana, Louisiana, Michigan, Nebraska, New Jersey, New York, Pennsylvania, Tennessee, Texas, Utah, Wisconsin, and Wyoming. 

According to the The Louisiana Department of Health and Hospitals, West Nile infections are characterized in three ways: neuroinvasive, West Nile fever and asymptomatic. A neuroinvasive disease illness is caused by West Nile virus attacking the nerve cells. In older people, it may be very severe and could result in brain damage or death. West Nile fever is less severe, with most people only suffering mild, flu-like symptoms. Asymptomatic individuals were never ill and were only discovered to have the West Nile virus in their blood when blood work was done for some other reason, such as blood donation.

About 90 percent of all cases are asymptomatic, while about 10 percent will develop West Nile fever. Only a very small number of infected individuals will show the serious symptoms associated with the neuroinvasive disease. Residents who are 65 years old and older are at higher risk for complications, but everyone is at risk for infection. For more infectious disease news and information, visit and “like” the Infectious Disease News Facebook page

Nationally in 2013, the Centers for Disease Control and Prevention (CDC) reported 2,374 WNV cases and 114 deaths. This was a far cry from the 2012 outbreak that had a final total of  5,674 cases of West Nile virus disease in people, including 286 deaths. The 2012 numbers were the highest for West Nile since 2003.

Precautions to take against mosquito bites include the following:

  • Use an insect repellent containing DEET on exposed skin and clothing when you go outdoors, particularly if you are outside between dusk and dawn when mosquitoes are more likely to bite. Insect repellent with permethrin should be used on clothing only.
  • Repair or install window and door screens to keep mosquitoes out of your home.
  • Prevent items such as buckets, cans, pool covers, flower pots, and tires from holding standing water so mosquitoes don’t have a place to breed.
  • Empty your pet’s outdoor water bowl and refill daily.
  • Clean leaves and debris from rain gutters regularly to ensure they are not clogged.